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Abstract: Jagim, AR, Harty, PS, Jones, MT, Fields, JB, Magee, M, Smith-Ryan, AE, Luedke, J, and Kerksick, CM. Fat-free mass index in sport: normative profiles and applications for collegiate athletes. J Strength Cond Res 38(9): 1687-1693, 2024-Recent concerns have been raised regarding the ethical considerations of conducting body composition assessments in sports. Specific apprehensions pertain to the inappropriate use of percent body fat and the limited application of the results to performance and recovery. Fat-free mass index (FFMI), a height-adjusted assessment of FFM, can serve as an alternative body composition metric to focus on in sports. Fat-free mass index provides valuable context regarding an optimal amount of FFM, accounting for skeletal frame and height while helping to qualify an athlete's FFM as low, moderate, or high. This review posits that shifting the focus of body composition measures to FFM can support more ideal targets across athletic seasons, careers, and the return to play after injury. In addition, a FFM focus may help change the perception of body composition assessment and how athletes perceive their current body because of the increased focus on the FFM compartment and the goal of maximizing tissue accrual, rather than focusing on fat loss. Fat-free mass index is calculated by dividing FFM (kg) by height (m 2 ) and can serve to normalize FFM, relative to height, and enable comparisons across athletes, sport types, and sex. Previous research has identified differences in FFMI across sex and among sport categories. Still, there is a need for more published data to develop optimal ranges for FFMI across sex, sports, and positions. As more data become available, FFMI has the potential to provide normative guidelines for optimal FFM development, performance, and injury risk reduction. The purpose of the current review was to summarize FFMI values across collegiate sport categories and competitive status to provide normative profiles, according to sex and sport type., (Copyright © 2024 National Strength and Conditioning Association.)

Background: Pre-exercise meal frequency is commonly believed to impact exercise performance, but little is known about its impact on resistance training., Objective: This study investigated the impact of breakfast consumption on afternoon resistance training performance in habitual breakfast consumers and nonconsumers., Design: A randomized, crossover study was conducted in Lubbock, TX between November 2021 and May 2022., Participants: Thirty-nine resistance-trained male (n = 20) and female (n = 19) adults (mean ± SD age 23.0 ± 4.7 years) who habitually consumed (≥5 d/wk; n = 19) or did not consume (≥5 d/wk; n = 20) breakfast completed the study., Intervention: After the establishment of 1-repetition maximums at the first visit, participants completed 2 additional visits, each of which included 4 sets of barbell back squat, bench press, and deadlift, using 80% of their 1-repetition maximum after either consuming breakfast and lunch or the same food at lunch only., Main Outcome Measures: Repetitions, along with average and peak average concentric velocity and power, were measured for all repetitions throughout each exercise session. Visual analog scales were used to assess feelings of fatigue, energy, focus, hunger, desire to eat, and fullness throughout each exercise session., Statistical Analyses Performed: Data were analyzed using linear mixed-effects models., Results: No interactions or main effects involving condition or habitual breakfast consumption were observed for resistance training outcomes, although sex differences were noted. Male participants performed significantly fewer repetitions on sets 2, 3, and 4 (P < .014) for total repetitions, on sets 2 and 4 for barbell back squat (P < .023), and set 4 for deadlift (P = .006), with no observed differences between sexes for bench press repetitions. Male participants displayed reductions in average power across all sets and exercises except deadlift., Conclusions: These data suggest that alterations in pre-exercise meal frequency may not influence afternoon resistance training performance provided similar total nutritional intake is consumed., (Copyright © 2024 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.)

This study compared flavored kefir (KFR) and flavored milk (MLK) as a recovery drink in endurance master athletes. Using a randomized, placebo-controlled, non-blinded crossover design, 11 males and females completed three testing visits whilst acutely ingesting either KFR, MLK, or water as a placebo (PLA). KFR supplementation occurred for 14 days before the KFR-testing day, followed by a 3-week washout period. Testing visits consisted of an exhausting-exercise (EE) bout, a 4-h rest period where additional carbohydrate feeding was provided, and a treadmill 5 km time trial (TT). The Gastrointestinal Symptom Rating Scale (GSRS) survey was assessed at four timepoints. Blood was collected at baseline and after the TT and was analyzed for I-FABP levels. No significant difference (PLA: 33:39.1 ± 6:29.0 min, KFR: 33:41.1 ± 5:44.4 min, and MLK: 33:36.2 ± 6:40.5 min, p = 0.99) was found between the groups in TT performance. The KFR GSRS total score was significantly lower than the PLA after EE ( p = 0.005). No differences in I-FABP were observed between conditions. In conclusion, acute KFR supplementation did not impact TT performance or I-FABP levels but may have reduced subjective GI symptoms surrounding exercise when compared to MLK or PLA.

Position Statement: The International Society of Sports Nutrition (ISSN) bases the following position stand on a critical analysis of the literature regarding the effects of energy drink (ED) or energy shot (ES) consumption on acute exercise performance, metabolism, and cognition, along with synergistic exercise-related performance outcomes and training adaptations. The following 13 points constitute the consensus of the Society and have been approved by the Research Committee of the Society: Energy drinks (ED) commonly contain caffeine, taurine, ginseng, guarana, carnitine, choline, B vitamins (vitamins B1, B2, B3, B5, B6, B9, and B12), vitamin C, vitamin A (beta carotene), vitamin D, electrolytes (sodium, potassium, magnesium, and calcium), sugars (nutritive and non-nutritive sweeteners), tyrosine, and L-theanine, with prevalence for each ingredient ranging from 1.3 to 100%. Energy drinks can enhance acute aerobic exercise performance, largely influenced by the amount of caffeine (> 200 mg or >3 mg∙kg bodyweight [BW -1 ]) in the beverage. Although ED and ES contain several nutrients that are purported to affect mental and/or physical performance, the primary ergogenic nutrients in most ED and ES based on scientific evidence appear to be caffeine and/or the carbohydrate provision. The ergogenic value of caffeine on mental and physical performance has been well-established, but the potential additive benefits of other nutrients contained in ED and ES remains to be determined. Consuming ED and ES 10-60 minutes before exercise can improve mental focus, alertness, anaerobic performance, and/or endurance performance with doses >3 mg∙kg BW -1 . Consuming ED and ES containing at least 3 mg∙kg BW -1 caffeine is most likely to benefit maximal lower-body power production. Consuming ED and ES can improve endurance, repeat sprint performance, and sport-specific tasks in the context of team sports. Many ED and ES contain numerous ingredients that either have not been studied or evaluated in combination with other nutrients contained in the ED or ES. For this reason, these products need to be studied to demonstrate efficacy of single- and multi-nutrient formulations for physical and cognitive performance as well as for safety. Limited evidence is available to suggest that consumption of low-calorie ED and ES during training and/or weight loss trials may provide ergogenic benefit and/or promote additional weight control, potentially through enhanced training capacity. However, ingestion of higher calorie ED may promote weight gain if the energy intake from consumption of ED is not carefully considered as part of the total daily energy intake. Individuals should consider the impact of regular coingestion of high glycemic index carbohydrates from ED and ES on metabolic health, blood glucose, and insulin levels. Adolescents (aged 12 through 18) should exercise caution and seek parental guidance when considering the consumption of ED and ES, particularly in excessive amounts (e.g. > 400 mg), as limited evidence is available regarding the safety of these products among this population. Additionally, ED and ES are not recommended for children (aged 2-12), those who are pregnant, trying to become pregnant, or breastfeeding and those who are sensitive to caffeine. Diabetics and individuals with preexisting cardiovascular, metabolic, hepatorenal, and/or neurologic disease who are taking medications that may be affected by high glycemic load foods, caffeine, and/or other stimulants should exercise caution and consult with their physician prior to consuming ED. The decision to consume ED or ES should be based upon the beverage's content of carbohydrate, caffeine, and other nutrients and a thorough understanding of the potential side effects. Indiscriminate use of ED or ES, especially if multiple servings per day are consumed or when consumed with other caffeinated beverages and/or foods, may lead to adverse effects. The purpose of this review is to provide an update to the position stand of the International Society of Sports Nutrition (ISSN) integrating current literature on ED and ES in exercise, sport, and medicine. The effects of consuming these beverages on acute exercise performance, metabolism, markers of clinical health, and cognition are addressed, as well as more chronic effects when evaluating ED/ES use with exercise-related training adaptions.

Background: Thermogenic supplements are often consumed by individuals seeking to improve energy levels and reduce body fat. These supplements are sold in powdered or ready-to-drink (RTD) forms and consist of a blend of ingredients such as caffeine, green tea extract, and other botanical compounds. While there is evidence that thermogenic supplements can positively affect resting energy expenditure (REE), the effect varies based on the combination of active ingredients. Additionally, there is some concern that thermogenic supplements may cause unwanted side effects on hemodynamic variables, like heart rate (HR) and blood pressure (BP). Therefore, further investigation into the efficacy and safety of commercially available products is warranted., Methods: Twenty-eight individuals (14 F, 14 M; age: 23.3 ± 3.9 yrs; height: 169.4 ± 8.6 cm; body mass: 73.3 ± 13.1 kg) completed two visits in a randomized, double-blind, crossover fashion. Each visit began with baseline REE, HR, and BP assessments, which were followed by ingestion of an active RTD thermogenic beverage (RTD; OxyShred Ultra Energy) or placebo (PL). Assessments were repeated at the intervals of 35-50- and 85-100-minutes post-ingestion. In addition, subjective outcomes of energy, focus, concentration, alertness, and mood were collected five times throughout each visit. Repeated-measures analysis of variance was performed with condition and time specified as within-subjects factors and sex and resistance training (RT) status as between-subjects factors. Statistical significance was accepted at p  < 0.05., Results: A significant condition × time interaction was observed for REE ( p  < 0.001). Higher REE values were demonstrated at 35-50 min (0.08 ± 0.02 kcal/min; p  = 0.001; 5.2% difference) and 85-100 min (0.08 ± 0.02 kcal/min; p  = 0.001; 5.5% difference) after RTD ingestion as compared to PL. No significant condition × time interactions were observed for respiratory quotient, HR, or BP. Condition main effects indicated lower HR (3.0 ± 0.9 bpm; p  = 0.003), higher SBP (3.5 ± 1.1 mm Hg; p  = 0.003) and higher DBP (3.5 ± 0.9 mm Hg; p  < 0.001) in RTD as compared to PL, irrespective of time. Condition × time interactions were observed for all subjective outcomes ( p  ≤ 0.02). Post hoc tests indicated statistically significant benefits of the RTD over PL for energy, focus, concentration, and alertness, without significant differences for mood after correction for multiple comparisons. Sex and RT status were not involved in interactions for any outcomes, except for a Sex × RT status interaction for energy, indicating higher energy ratings in non-resistance-trained vs. resistance-trained males., Conclusions: These data suggest that acute ingestion of a thermogenic RTD beverage significantly increases REE, and this elevated caloric expenditure is sustained for at least 100 minutes following ingestion. Furthermore, the RTD beverage increased measures of energy, focus, concentration, and alertness as compared to placebo. While minor differences in hemodynamic variables were observed between conditions, all values stayed within normal ranges. Individuals aiming to increase energy expenditure may benefit from acute ingestion of an RTD thermogenic supplement.

The prevalence of dietary supplement use among athletes continues to rise with 60-80% of athletes often reporting current or previous use of dietary supplements. While select dietary ingredients have been shown to improve acute performance and enhance training adaptations over time, it is important to still consider the risk vs. reward for athletes before opting to consume a dietary supplement. Previous work has indicated that certain dietary supplements may pose risks for inadvertent doping, may be susceptible to mislabelling, could be banned by certain governing bodies of sport, or pose health risks for certain populations. The purpose of the current narrative review is to summarize the prevalence of adulteration in dietary sport supplement products, outline the risks of inadvertent doping for athletes, and highlight best practices regarding safe supplementation strategies. Analytical studies have found anywhere from 14 to 50% of samples analyzed from dietary supplement products have tested positive for anabolic agents or other prohibited substances. It is important for the consumer to adhere to safe supplementation strategies, which include following serving size recommendations, cross-referencing ingredient profiles with the list of prohibited substances, choosing quality products that have been verified by a third-party certification program, and being cognizant of consuming multiple dietary supplement products with overlapping ingredient profiles. Once these practices have been considered, it is reasonable for an athlete to utilize dietary supplements as a strategy to optimize performance and health, with a low risk of failing a drug test (adverse analytical finding) and experiencing adverse events., Competing Interests: AJ, DG, and AG have consulted with and received external funding from companies who sell certain dietary ingredients and write for online and other media outlets on topics related to exercise and nutrition. GT has received research funding or other research support from several companies producing sports supplements. He also serves as a paid consultant for sports nutrition companies. None of these entities played any role in the present article. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest, (© 2023 Jagim, Harty, Erickson, Tinsley, Garner and Galpin.)

The purpose of this investigation was to expand upon the limited existing research examining the test-retest reliability, cross-sectional validity and longitudinal validity of a sample of bioelectrical impedance analysis (BIA) devices as compared with a laboratory four-compartment (4C) model. Seventy-three healthy participants aged 19-50 years were assessed by each of fifteen BIA devices, with resulting body fat percentage estimates compared with a 4C model utilising air displacement plethysmography, dual-energy X-ray absorptiometry and bioimpedance spectroscopy. A subset of thirty-seven participants returned for a second visit 12-16 weeks later and were included in an analysis of longitudinal validity. The sample of devices included fourteen consumer-grade and one research-grade model in a variety of configurations: hand-to-hand, foot-to-foot and bilateral hand-to-foot (octapolar). BIA devices demonstrated high reliability, with precision error ranging from 0·0 to 0·49 %. Cross-sectional validity varied, with constant error relative to the 4C model ranging from -3·5 (sd 4·1) % to 11·7 (sd 4·7) %, standard error of the estimate values of 3·1-7·5 % and Lin's concordance correlation coefficients (CCC) of 0·48-0·94. For longitudinal validity, constant error ranged from -0·4 (sd 2·1) % to 1·3 (sd 2·7) %, with standard error of the estimate values of 1·7-2·6 % and Lin's CCC of 0·37-0·78. While performance varied widely across the sample investigated, select models of BIA devices (particularly octapolar and select foot-to-foot devices) may hold potential utility for the tracking of body composition over time, particularly in contexts in which the purchase or use of a research-grade device is infeasible.

This study evaluated the influence of novel beverage formulations on bioimpedance- and urine-based hydration markers. Thirty young healthy adults (n=16 females, n=14 males; age: 23.2±3.7 years; BMI: 24.3±3.3 kg/m 2 ) participated in a randomized, double-blind, placebo-controlled, crossover study. Participants completed three conditions with baseline bioimpedance, urine, and body mass assessments, followed by ingestion of one liter of a test beverage over a 30-minute period. The three beverages were: active hydration formulation in still (AFstill) or sparkling (AFspark) water and a still water control. The active formulations were identical in concentrations of alpha-cyclodextrin and complexing agents. Following beverage ingestion, bioimpedance assessments were performed every 15 minutes for two hours, followed by final urinary and body mass assessments. The primary bioimpedance outcomes were phase angle at 50 kHz, resistance of the extra-cellular compartment (R 0 ), and resistance of the intracellular compartment (Ri). Data were analyzed using linear mixed effects models, Friedman tests, and Wilcoxon tests. Statistically significant changes in phase angle values were observed at 30 (p=0.004) and 45 minutes (p=0.024) following the initiation of beverage ingestion in the AFstill condition as compared to the reference model (i.e., control condition at baseline). Although differences between conditions were not statistically significant at later time points, the data were consistent with AFstill having greater elevations in phase angle throughout the monitoring period. At the 30-minute time point only, statistically significant differences in R 0 for AFspark (p<0.001) and in Ri for AFstill (p=0.008) were observed. When averaged across post-ingestion time points, there was a trend (p=0.08) for Ri differences between conditions. The net fluid balance was greater than zero, indicating retention of ingested fluid, for AFstill (p=0.02) and control (p=0.03), with a trend for AFspark (p=0.06). In conclusion, an active formulation containing alpha-cyclodextrin in still water demonstrated potential benefits for enhancing hydration markers in humans., Competing Interests: Conflict of interest Authors state no conflict of interest. This study was funded through research grants from 8 POiNT LLC, who is leading scientific and product validation on a patented hydration technology (Award Numbers A21-0085-001, A21-0085-002, and A21-0284-001). 8 POiNT LLC provided general input on the outcomes of interest but did not play a direct role in the details of study design, nor any role in data collection or analysis. Per the research contract, the sponsor was allowed to review the manuscript for technical considerations but did not play other roles in the writing of the manuscript., (© 2023 Grant M. Tinsley et al., published by Sciendo.)

The purpose of this preliminary analysis was to determine if there are relationships between anthropometric characteristics (arm length, torso length, thigh length, and shank length) and conventional deadlift (CDL) kinematics and kinetics during a 5 sets of 5 repetitions (5 × 5) CDL routine in resistance-trained males. Eleven males who had experience with the deadlift exercise were included in this analysis (age: 21.5 ± 1.4 y; height: 180.7 ± 5.7 cm; body mass: 89.9 ± 16.0 kg). Anthropometrics were measured by a 3-dimensional optical scanner. The participants underwent a 5 × 5 CDL workout using a self-selected load corresponding to a rating of perceived exertion (RPE) of 8 out of 10. Performance outcomes were measured synchronously using a 3-dimensional 12-camera motion capture system and two force platforms. Outcomes were averaged across all sets and analyzed using multiple linear regression. The selected anthropometric variables were not significantly related to the CDL performance outcomes, except for concentric ankle work. However, in the overall model, anthropometric predictors did not significantly predict ankle concentric work ( p = 0.11; R 2 = 0.67; R&#95;2adj = 0.45). Independently, thigh length significantly correlated with ankle concentric work ( p = 0.03). In this model, thigh length accounted for 55% of the normalized variance in ankle concentric work. The results from this preliminary study suggest that arm length, torso length, and shank length may not play a clear role in the examined CDL outcomes, but thigh length may be positively correlated with ankle concentric work during a 5 × 5 CDL routine in resistance-trained males.

Abstract: Harty, PS, Friedl, KE, Nindl, BC, Harry, JR, Vellers, HL, and Tinsley, GM. Military body composition standards and physical performance: historical perspectives and future directions. J Strength Cond Res 36(12): 3551-3561, 2022-US military physique and body composition standards have been formally used for more than 100 years. These metrics promote appropriate physical fitness, trim appearance, and long-term health habits in soldiers, although many specific aspects of these standards have evolved as evidence-based changes have emerged. Body composition variables have been shown to be related to many physical performance outcomes including aerobic capacity, muscular endurance, strength and power production, and specialized occupational tasks involving heavy lifting and load carriage. Although all these attributes are relevant, individuals seeking to improve military performance should consider emphasizing strength, hypertrophy, and power production as primary training goals, as these traits appear vital to success in the new Army Combat Fitness Test introduced in 2020. This fundamental change in physical training may require an adjustment in body composition standards and methods of measurement as physique changes in modern male and female soldiers. Current research in the field of digital anthropometry (i.e., 3-D body scanning) has the potential to dramatically improve performance prediction algorithms and potentially could be used to inform training interventions. Similarly, height-adjusted body composition metrics such as fat-free mass index might serve to identify normal weight personnel with inadequate muscle mass, allowing for effective targeted nutritional and training interventions. This review provides an overview of the origin and evolution of current US military body composition standards in relation to military physical readiness, summarizes current evidence relating body composition parameters to aspects of physical performance, and discusses issues relevant to the emerging modern male and female warrior., (Copyright © 2022 National Strength and Conditioning Association.)

Abstract: Rodriguez, C, Harty, PS, Stratton, MT, Siedler, MR, Smith, RW, Johnson, BA, Dellinger, JR, Williams, AD, White, SJ, Benavides, ML, and Tinsley, GM. Comparison of indirect calorimetry and common prediction equations for evaluating changes in resting metabolic rate induced by resistance training and a hypercaloric diet. J Strength Cond Res 36(11): 3093-3104, 2022-The ability to accurately identify resting metabolic rate (RMR) changes over time allows practitioners to prescribe appropriate adjustments to nutritional intake. However, there is a lack of data concerning the longitudinal utility of commonly used RMR prediction equations. The purpose of this study was to evaluate the validity of several commonly used prediction equations to track RMR changes during a hypercaloric nutritional intervention and supervised resistance exercise training program. Twenty resistance-trained men completed the study. The protocol lasted 6 weeks, and subjects underwent RMR assessments by indirect calorimetry (IC) preintervention and postintervention to obtain reference values. Existing RMR prediction equations based on body mass (BM) or dual-energy X-ray absorptiometry fat-free mass (FFM) were also evaluated. Equivalence testing was used to evaluate whether each prediction equation demonstrated equivalence with IC. Null hypothesis significance testing was also performed, and Bland-Altman analysis was used alongside linear regression to assess the degree of proportional bias. Body mass and FFM increased by 3.6 ± 1.7 kg and 2.4 ± 1.6 kg, respectively. Indirect calorimetry RMR increased by 165 ± 97 kcal·d -1 , and RMR:FFM increased by 5.6 ± 5.2%. All prediction equations underestimated mean RMR changes relative to IC, with magnitudes ranging from 75 to 155 kcal·d -1 , while also displaying unacceptable levels of negative proportional bias. In addition, no equation demonstrated equivalence with IC. Common RMR prediction equations based on BM or FFM did not fully detect the increase in RMR observed with resistance training plus a hypercaloric diet. Overall, the evaluated prediction equations are unsuitable for estimating RMR changes in the context of this study., (Copyright © 2021 National Strength and Conditioning Association.)

Multivitamin/mineral (MVM) supplements are one of the most popular dietary supplement categories. The purpose of this analysis was to determine if a novel liposomal delivery mechanism improves mineral absorption from an MVM product. In a randomized crossover trial, 25 healthy participants (12 females, 13 males) completed two testing sessions in which blood samples were collected at baseline and 2, 4, and 6 h following the ingestion of either a liposomal MVM or a nutrient-matched standard MVM. Analysis of MVM products indicated an elemental iron content of 9.4 and 10.1 mg (~50% U.S. FDA Daily Value) and an elemental magnesium content of 22.0 and 23.3 mg (~5% U.S. FDA Daily Value) in the liposomal and standard MVM products, respectively. Blood samples were analyzed for concentrations of iron and magnesium using colorimetric assays. Changes in mineral concentrations were analyzed using linear mixed models, and pharmacokinetic parameters were compared between conditions. For iron, statistically significant condition × time interactions were observed for percent change from baseline ( p = 0.002), rank of percent change from baseline ( p = 0.01), and raw concentrations ( p = 0.02). Follow-up testing indicated that the liposomal condition exhibited larger changes from baseline than the standard MVM condition at 4 ( p = 0.0001; +14.3 ± 18.5% vs. -6.0 ± 13.1%) and 6 h ( p = 0.0002; +1.0 ± 20.9% vs. -21.0 ± 15.3%) following MVM ingestion. These changes were further supported by a 50% greater mean incremental area under the curve in the liposomal condition (33.2 ± 30.9 vs. 19.8 ± 19.8 mcg/dL × 6 h; p = 0.02, Cohen's d effect size = 0.52). In contrast, no differential effects for magnesium absorption were observed. In conclusion, iron absorption from an MVM product is enhanced by a liposomal delivery mechanism.

Abstract: Brandner, CF, Harty, PS, Luedke, JA, Erickson, JL, and Jagim, AR. Sport differences in fat-free mass index among a diverse sample of NCAA Division III collegiate athletes. J Strength Cond Res 36(8): 2212-2217, 2022-Fat-free mass index (FFMI) is becoming a popular metric to determine an athlete's potential for future fat-free mass accrual or to identify athletes who may be at risk for low fat-free mass (FFM). The aim of the current study was to examine sport-specific differences in FFMI among a cohort of collegiate athletes. NCAA Division III male ( n = 98; age: 20.1 ± 1.6 years, height: 1.82 ± 0.06 m, body mass: 92.7 ± 17.5 kg, %BF: 15.6 ± 8.8%) and female ( n = 92; age: 19.45 ± 1.1 years, height: 1.68 ± 0.06 m, body mass: 65.16 ± 11.04 kg, %BF: 22.71 ± 5.9%) athletes completed a body composition assessment using air displacement plethysmography. Fat-free mass index was calculated by dividing FFM by height squared. The mean ± SD FFMI was significantly higher ( p < 0.05) for males (23.37 ± 2.41 kg·m -2 ) compared with females (17.54 ± 1.8 kg·m -2 ). There was a significant main effect for sport category. Post hoc analysis indicated that throwers had a higher ( p < 0.001) FFMI (mean difference, 95% confidence interval) compared with sprinters and soccer athletes (4.17, 2.03-6.32 kg·m -2 ), endurance and weight-sensitive athletes (4.91, 2.67-7.14 kg·m -2 ), and court sport athletes (4.39, 1.97-6.81 kg·m -2 ), respectively, among female athletes. Post hoc analysis indicated that football players had a higher ( p < 0.01) FFMI than distance runners (3.89, 2.15, 5.62) and wrestlers (2.23, 0.78, 3.68), among male athletes. These findings indicate that sex differences in FFMI exist, with differences identified between sports. These findings can guide strength and nutritional programming decisions by providing sport-specific normative data profiles., (Copyright © 2022 National Strength and Conditioning Association.)

The present study reports the validity of multiple assessment methods for tracking changes in body composition over time and quantifies the influence of unstandardised pre-assessment procedures. Resistance-trained males underwent 6 weeks of structured resistance training alongside a hyperenergetic diet, with four total body composition evaluations. Pre-intervention, body composition was estimated in standardised (i.e. overnight fasted and rested) and unstandardised (i.e. no control over pre-assessment activities) conditions within a single day. The same assessments were repeated post-intervention, and body composition changes were estimated from all possible combinations of pre-intervention and post-intervention data. Assessment methods included dual-energy X-ray absorptiometry (DXA), air displacement plethysmography, three-dimensional optical imaging, single- and multi-frequency bioelectrical impedance analysis, bioimpedance spectroscopy and multi-component models. Data were analysed using equivalence testing, Bland-Altman analysis, Friedman tests and validity metrics. Most methods demonstrated meaningful errors when unstandardised conditions were present pre- and/or post-intervention, resulting in blunted or exaggerated changes relative to true body composition changes. However, some methods - particularly DXA and select digital anthropometry techniques - were more robust to a lack of standardisation. In standardised conditions, methods exhibiting the highest overall agreement with the four-component model were other multi-component models, select bioimpedance technologies, DXA and select digital anthropometry techniques. Although specific methods varied, the present study broadly demonstrates the importance of controlling and documenting standardisation procedures prior to body composition assessments across distinct assessment technologies, particularly for longitudinal investigations. Additionally, there are meaningful differences in the ability of common methods to track longitudinal body composition changes.

This study evaluated the influence of acute water ingestion and maintaining an upright posture on raw bioimpedance and subsequent estimates of body fluids and composition. Twenty healthy adults participated in a randomized crossover study. In both conditions, an overnight food and fluid fast was followed by an initial multi-frequency bioimpedance assessment (InBody 770). Participants then ingested 11 mL/kg of water (water condition) or did not (control condition) during a 5-minute period. Thereafter, bioimpedance assessments were performed every 10 minutes for one hour with participants remaining upright throughout. Linear mixed effects models were used to examine the influence of condition and time on raw bioimpedance, body fluids, and body composition. Water consumption increased impedance of the arms but not trunk or legs. However, drift in leg impedance was observed, with decreasing values over time in both conditions. No effects of condition on body fluids were detected, but total body water and intracellular water decreased by ~0.5 kg over time in both conditions. Correspondingly, lean body mass did not differ between conditions but decreased over the measurement duration. The increase in body mass in the water condition was detected exclusively as fat mass, with final fat mass values ~1.3 kg higher than baseline and also higher than the control condition. Acute water ingestion and prolonged standing exert practically meaningful effects on relevant bioimpedance variables quantified by a modern, vertical multi-frequency analyzer. These findings have implications for pre-assessment standardization, methodological reporting, and interpretation of assessments., Competing Interests: Conflict of interest Authors state no conflict of interest. The bioimpedance analyzer utilized in the present study was loaned to the investigators by the manufacturer (InBody; contract #C14618). As specified in the contract, the manufacturer was allowed to review the manuscript to ensure that the technology was accurately depicted but did not influence the presentation of the findings. However, the manufacturer did provide technical information regarding their analyzer for inclusion in the methods section of the manuscript. The authors would like to acknowledge Mark Sanders for his assistance with this project., (© 2022 Grant M. Tinsley, Matthew T. Stratton, Patrick S. Harty, Abegale D. Williams, Sarah J. White, Christian Rodriguez, Jacob R. Dellinger, Baylor A. Johnson, Robert W. Smith, Eric T. Trexler, published by Sciendo.)

Background: There is substantial consumer and practitioner interest in an emerging supplement class known as multi-ingredient pre-workout supplements (MIPS), largely due to their prevalence in resistance training communities as well as research findings demonstrating the ergogenic impact of caffeine on muscular performance. However, limited research has examined the potential efficacy of non-caffeinated MIPS, despite their growing popularity among those who are caffeine-sensitive or who train later in the day., Methods: Twenty-four resistance-trained college-aged males (n = 12) and females (n = 12) completed three visits in which they ingested either a caffeinated MIPS (C), an otherwise identical non-caffeinated MIPS (NC), or placebo in a double-blind, counterbalanced, crossover fashion. Squat isometric peak force (PF iso ), rate of force development (RFD), and isokinetic performance were assessed. Upper and lower body maximal muscular strength and endurance were evaluated using the bench press and leg press, respectively. Visual analog scales for energy, focus, and fatigue were completed five times throughout the testing protocol. The effects of supplementation and biological sex on all variables were examined using linear mixed effects models., Results: Significantly greater PF iso was observed in both C ( b : 0.36 transformed units [0.09, 0.62]) and NC ( b : 0.32 transformed units [95% CI: 0.05, 0.58]) conditions, relative to placebo. Early RFD (RFD 50 ) may have been higher with supplementation, particularly in females, with no effects for late RFD (RFD 200 ) or peak RFD. In addition, increases in subjective energy after supplement ingestion were noted for C, but not NC. No effects of supplementation on traditional resistance exercise performance or isokinetic squat performance were observed, other than a lower leg press one-repetition maximum for males in the NC condition., Conclusions: These data indicate that acute ingestion of either a caffeinated or non-caffeinated pre-workout formulation improved maximal force production during an isometric squat test but did not provide additional benefit to leg press, bench press, or isokinetic squat performance over placebo, within the context of a laboratory environment. The consumption of a caffeinated, but not non-caffeinated, MIPS increased subjective ratings of energy over placebo when assessed as part of a testing battery., Competing Interests: No potential conflict of interest was reported by the author(s)., (© 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

Intermittent fasting (IF) is a dietary strategy that involves alternating periods of abstention from calorie consumption with periods of ad libitum food intake. There is significant interest in the body of literature describing longitudinal adaptations to IF. Less attention has been given to the acute physiological responses that occur during the fasting durations that are commonly employed by IF practitioners. Thus, the purpose of this review was to examine the physiological responses - including alterations in substrate metabolism, systemic hormones, and autophagy - that occur throughout an acute fast. Literature searches were performed to locate relevant research describing physiological responses to acute fasting and short-term starvation. A single fast demonstrated the ability to alter glucose and lipid metabolism within the initial 24 hours, but variations in protein metabolism appeared to be minimal within this time frame. The ability of an acute fast to elicit significant increases in autophagy is still unknown. The information summarized in this review can be used to help contextualize existing research and better inform development of future IF interventions., (© The Author(s) 2021. Published by Oxford University Press on behalf of the International Life Sciences Institute. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Energy drinks are one of the most popular packaged beverage products consumed within the United States (US). Energy drinks are considered a functional beverage, a category that also includes sports drinks and nutraceutical beverages., Purpose: The focus of the current study was to examine the nutrition fact panels of the top selling commercially available energy drink and energy shot products within the US to characterize common ingredient profiles to help establish a standard definition and ingredient profile of energy drinks and energy shots for consumers, health care practitioners, and researchers., Methods: The top 75 commercially available energy drinks and shots were identified and compiled from multiple commercial retail websites as of September 2021. For the purpose of this study, an energy drink must have met the following criteria: (A) marketed as an energy drink; (B) purported to improve energy, focus, or alertness; (C) not sold as a dietary supplement (no supplement fact panels); (D) manufactured as a pre-packaged and ready-to-drink beverage; and (E) contains at least three of (1) caffeine, (2) B-vitamins, (3) sugar, (4) taurine, (5) creatine, (6) quercetin, (7) guarana, (8) ginseng, (9) coenzyme Q10, or (10) branched chain amino acids. Energy shots must have met similar criteria to be included: (A) marketed as an energy shot; (B) purported to improve energy, focus, or alertness; (C) sold as a dietary supplement; (D) manufactured as a pre-packaged beverage with a small volume (<3.5 mL); and (E) contains at least three of the ingredients stated above., Results: Twenty energy shots and fifty-five energy drinks were included in this analysis. The number of ingredients per product (mean ± SD) was 18.2 ± 5.7, with 15 products containing proprietary blends with undisclosed ingredient amounts. The relative prevalence and average amounts of the top ingredients were as follows: caffeine (100%; 174.4 ± 81.1 mg), vitamin B6 (72%; 366.9 ± 648.1 percent daily value (%DV)), vitamin B3 (67%; 121.44 ± 69.9% DV), vitamin B12 (67%; 5244.5 ± 10,474.6% DV), vitamin B5 (37.3%; 113.6 ± 76.6% DV), and taurine (37.3%; amounts undisclosed)., Conclusions: Our findings suggest a high prevalence of caffeine and B-vitamins in these energy products, with many of the formulations containing well above the recommended daily value of B-vitamins.

Abstract: Harty, PS, Zabriskie, HA, Stecker, RA, Currier, BS, Moon, JM, Richmond, SR, Jagim, AR, and Kerksick, CM. Position-specific body composition values in female collegiate rugby union athletes. J Strength Cond Res 35(11): 3158-3163, 2021-Rugby union is a full-contact, intermittent team sport. Anthropometric characteristics of rugby union athletes have been shown to influence suitability for a given position and affect performance. However, little anthropometric data exist in female rugby union athletes. Thus, the purpose of this study was to report position-specific anthropometric, body composition, and bone density values in female collegiate rugby union athletes and to identify between-position differences in these variables. This investigation was a cross-sectional study involving 101 female collegiate rugby union athletes, categorized as forwards and backs as well as by position (props, hookers, locks, flankers, number 8 forwards, halfback, fly-half, centers, wings, and fullbacks). Anthropometric characteristics of all athletes were measured, and body composition was assessed via dual-energy x-ray absorptiometry. Outcome variables included age, height, body mass, BMI, body fat percentage, fat mass (FM), FM index, fat-free mass (FFM), FFM index, lean soft tissue, bone mineral content, bone mineral area, and bone mineral density. Anthropometric and body composition differences between forwards and backs were identified via independent t-tests and Mann-Whitney U tests, depending on normality of the variable. Between-position differences were assessed using one-way analysis of variances (ANOVAs) with Tukey post-hoc comparisons or Welch's ANOVA with Dunnett's T3 post-hoc test. Significant differences (p < 0.014) were identified between forwards and backs for every anthropometric variable, with forwards displaying greater height (167.7 ± 7.2 cm), body mass (81.5 ± 15.1 kg), and body fat percentage (28.2 ± 6.1%) relative to backs (164.5 ± 5.1 cm; 64.5 ± 7.7 kg; 21.9 ± 3.7%). Likewise, significant differences were identified for every anthropometric variable between several positions (p < 0.01). Significant (p < 0.05) interposition differences were identified within the subgroup of forwards, but not within the subgroup of backs. The present investigation is the first to report position-specific anthropometric and body composition data in female collegiate rugby union athletes. The results of this study can be used by rugby union coaches for recruiting and personnel decisions, to determine a player's suitability for a given position, and to further inform training and nutritional interventions in this population., (Copyright © 2019 National Strength and Conditioning Association.)

The present study examined cross-sectional and longitudinal relationships between total and segmental subcutaneous tissue thicknesses from ultrasonography (US) and total and segmental fat mass (FM) estimates from dual-energy X-ray absorptiometry (DXA). Traditional US FM estimates were also examined. Twenty resistance-trained males (mean ± SD; age: 22.0 ± 2.6 years; body mass: 74.8 ± 11.5 kg; DXA fat: 17.5 ± 4.5%) completed a 6-week supervised resistance training programme while consuming a hypercaloric diet. Pre- and post-intervention body composition was assessed by DXA and B-mode US. Data were analysed using Pearson's correlation (r), Lin's correlation coefficient (CCC), paired t-tests, Wilcoxon signed-rank tests and Bland-Altman analysis, as appropriate. Cross-sectionally, correlations were observed between total DXA FM and total subcutaneous tissue thickness (r = 0.88). Longitudinally, a correlation was observed between total DXA FM changes and total subcutaneous tissue changes (r = 0.49, CCC = 0.38). Correlations of similar magnitudes were observed for the upper body and trunk estimates, but DXA FM changes were unrelated to subcutaneous tissue changes for the lower body and arms. Cross-sectionally, US 2-compartment FM and DXA FM were correlated (r = 0.91, CCC = 0.83). Longitudinally, a weaker correlation was observed (r = 0.47, CCC = 0.33). In summary, longitudinal associations between US and DXA are weaker than cross-sectional relationships; additionally, correlations between US subcutaneous tissue and whole-body DXA FM appear to be driven by the trunk region rather than appendages. Reporting raw skinfold thicknesses rather than FM estimates alone may improve the utility of techniques based on subcutaneous tissue thickness, such as US and skinfolds., (© 2021 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.)

Background: Due to inherent errors involved in the transformation of raw bioelectrical variables to body fluids or composition estimates, the sole use of resistance (R), reactance (Xc), and phase angle (φ) has been advocated when quantifying longitudinal changes. The aim of this investigation was to assess the ability of four bioimpedance analyzers to detect raw bioimpedance changes induced by purposeful weight gain with resistance training., Methods: Twenty-one resistance trained males completed a 6-week lifestyle intervention with the aim of purposeful weight gain. Bioimpedance analysis was performed before and after the intervention using four different analyzers (MFBIA InBody : InBody 770; MFBIA SECA : Seca mBCA 515/514; BIS: ImpediMed SFB7; SFBIA: RJL Quantum V) for the quantification of R, Xc, and φ at the 50-kHz frequency. Repeated measures ANOVA and follow up tests were performed., Results: Analysis revealed main effects of time and method for R, Xc, and φ (p ≤ 0.02), without significant time x method interactions (p ≥ 0.07). Follow up for time main effects indicated that, on average, R decreased by 4.5-5.8%, Xc decreased by 2.3-4.0%, and φ increased by 1.8-2.6% across time for all analyzers combined. However, varying levels of disagreement in absolute values were observed for each bioelectrical variable., Conclusions: The differences in absolute bioelectrical values suggests that analyzers should not be used interchangeably, which holds particular importance when reference values are utilized. Despite absolute differences, analyzers with varying characteristics demonstrated similar abilities to detect changes in R, Xc, and φ over time.

Relatively few investigations have reported purposeful overfeeding in resistance-trained adults. This preliminary study examined potential predictors of resistance training (RT) adaptations during a period of purposeful overfeeding and RT. Resistance-trained males ( n = 28; n = 21 completers) were assigned to 6 weeks of supervised RT and daily consumption of a high-calorie protein/carbohydrate supplement with a target body mass (BM) gain of ≥0.45 kg·wk -1 . At baseline and post-intervention, body composition was evaluated via 4-component (4C) model and ultrasonography. Additional assessments of resting metabolism and muscular performance were performed. Accelerometry and automated dietary interviews estimated physical activity levels and nutrient intake before and during the intervention. Bayesian regression methods were employed to examine potential predictors of changes in body composition, muscular performance, and metabolism. A simplified regression model with only rate of BM gain as a predictor was also developed. Increases in 4C whole-body fat-free mass (FFM; (mean ± SD) 4.8 ± 2.6%), muscle thickness (4.5 ± 5.9% for elbow flexors; 7.4 ± 8.4% for knee extensors), and muscular performance were observed in nearly all individuals. However, changes in outcome variables could generally not be predicted with precision. Bayes R 2 values for the models ranged from 0.18 to 0.40, and other metrics also indicated relatively poor predictive performance. On average, a BM gain of ~0.55%/week corresponded with a body composition score ((∆FFM/∆BM)*100) of 100, indicative of all BM gained as FFM. However, meaningful variability around this estimate was observed. This study offers insight regarding the complex interactions between the RT stimulus, overfeeding, and putative predictors of RT adaptations.

Objective . Bioimpedance devices are commonly used to assess health parameters and track changes in body composition. However, the cross-sectional agreement between different devices has not been conclusively established. Thus, the objective of this investigation was to examine the agreement between raw bioelectrical variables (resistance, reactance, and phase angle at the 50 kHz frequency) obtained from three bioimpedance analyzers. Approach . Healthy male ( n  = 76, mean ± SD; 33.8 ± 14.5 years; 83.9 ± 15.1 kg; 179.4 ± 6.9 cm) and female ( n  = 103, mean ± SD; 33.4 ± 15.9 years; 65.6 ± 12.1 kg; 164.9 ± 6.4 cm) participants completed assessments using three bioimpedance devices: supine bioimpedance spectroscopy (BIS), supine single-frequency bioelectrical impedance analysis (SFBIA), and standing multi-frequency bioelectrical impedance analysis (MFBIA). Differences in raw bioelectrical variables between the devices were quantified via one-way analysis of variance for the total sample and for each sex. Equivalence testing was used to determine equivalence between methods. Main results . Significant differences in all bioelectrical variables were observed between the three devices when examining the total sample and males only. The devices appeared to exhibit slightly better agreement when analyzing female participants only. Equivalence testing using the total sample as well as males and females separately revealed that resistance and phase angle were equivalent between the supine devices (BIS, SFBIA), but not with the standing analyzer (MFBIA). Significance . The present study demonstrated disagreement between different bioimpedance analyzers for quantifying raw bioelectrical variables, with the poorest agreement between devices that employed different body positions during testing. These results suggest that researchers and clinicians should employ device-specific reference values to classify participants based on raw bioelectrical variables, such as phase angle. If reference values are needed but are unavailable for a particular bioimpedance analyzer, the set of reference values produced using the most similar analyzer and reference population should be selected., (© 2021 Institute of Physics and Engineering in Medicine.)

Energy needs of female team-sport athletes are poorly understood with no evidence highlighting differences present between scheduled activities. The purpose of this study was to examine the difference in energy expenditure between NCAA Division II female basketball (BBALL) and lacrosse (LAX) athletes during different scheduled team activities. Female BBALL ( n = 13; 19.8 ± 1.3 yrs; 173.9 ± 13.6 cm; 74.6 ± 9.1kg; 27.1 ± 3.2%fat) and LAX ( n = 20; 20.4 ± 1.8yrs; 168.4 ± 6.6cm; 68.8 ± 8.9kg; 27.9 ± 3.1%fat) athletes were outfitted with heart rate and activity monitors during four consecutive days on five different occasions (20 days total) across an entire academic year to assess differences in total daily activity energy expenditure (TDEE), activity energy expenditure (AEE), and physical activity level (PAL). Data were categorized by type of scheduled daily activities: Practice, Game, Conditioning, or Off. Independent of day type, TDEE, AEE, and PAL levels were greater ( p < 0.05) in BBALL athletes. For each sport, TDEE, AEE, and PAL were significantly different ( p < 0.05) between classified activity days. BBALL and LAX athletes experienced higher values on game days for TDEE, AEE, and PAL, with the lowest values experienced on off days. In conclusion, calculated levels of TDEE, AEE, and PAL in female collegiate BBALL and LAX athletes were determined to be different, irrespective of the scheduled activity.

Introduction/background: Few investigations have sought to explain discrepancies between dual-energy X-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA) body composition estimates. The purpose of this analysis was to explore physiological and anthropometric predictors of discrepancies between DXA and BIA total and segmental body composition estimates., Methodology: Assessments via DXA (GE Lunar Prodigy) and single-frequency BIA (RJL Systems Quantum V) were performed in 179 adults (103 F, 76 M, age: 33.6 ± 15.3 yr; BMI: 24.9 ± 4.3 kg/m 2 ). Potential predictor variables for differences between DXA and BIA total and segmental fat mass (FM) and lean soft tissue (LST) estimates were obtained from demographics and laboratory techniques, including DXA, BIA, bioimpedance spectroscopy, air displacement plethysmography, and 3-dimensional optical scanning. To determine meaningful predictors, Bayesian robust regression models were fit using a t-distribution and regularized hierarchical shrinkage "horseshoe" prior. Standardized model coefficients (β) were generated, and leave-one-out cross validation was used to assess model predictive performance., Results: LST hydration (i.e., total body water:LST) was a predictor of discrepancies in all FM and LST variables (|β|: 0.20-0.82). Additionally, extracellular fluid percentage was a predictor for nearly all outcomes (|β|: 0.19-0.40). Height influenced the agreement between whole-body estimates (|β|: 0.74-0.77), while the mass, length, and composition of body segments were predictors for segmental LST estimates (|β|: 0.23-3.04). Predictors of segmental FM errors were less consistent. Select sex-, race-, or age-based differences between methods were observed. The accuracy of whole-body models was superior to segmental models (leave-one-out cross-validation-adjusted R 2 of 0.83-0.85 for FM TOTAL and LST TOTAL vs. 0.20-0.76 for segmental estimates). For segmental models, predictive performance decreased in the order of: appendicular lean soft tissue, LST LEGS , LST TRUNK and FM LEGS , FM ARMS , FM TRUNK , and LST ARMS ., Conclusions: These findings indicate the importance of LST hydration, extracellular fluid content, and height for explaining discrepancies between DXA and BIA body composition estimates. These general findings and quantitative interpretation based on the presented data allow for a better understanding of sources of error between 2 popular segmental body composition techniques and facilitate interpretation of estimates from these technologies., (Copyright © 2020 The International Society for Clinical Densitometry. Published by Elsevier Inc. All rights reserved.)

Purpose: The purpose of this study was to assess the agreement between a field-based three-compartment (3CFIELD) model and a laboratory-based three-compartment (3CLAB) model for tracking body composition changes over time., Methods: Resistance-trained males completed a supervised nutrition and resistance training intervention. Before and after the intervention, assessments were performed via air displacement plethysmography (ADP), bioimpedance spectroscopy (BIS), portable ultrasonography (US), and bioelectrical impedance analysis (BIA). ADP body density and BIS body water were used within the reference 3CLAB model, whereas US-derived body density and BIA body water were used within the 3CFIELD model. Two-compartment model body composition estimates provided by US and BIA were also examined. Changes in fat-free mass and fat mass were analyzed using repeated-measures ANOVA, equivalence testing, Bland-Altman analysis, linear regression, and related validity analyses., Results: Significant increases in fat-free mass (3CLAB, 4.0 ± 4.5 kg; 3CFIELD, 3.9 ± 4.2 kg; US, 3.2 ± 4.3 kg; BIA, 3.9 ± 4.2 kg) and fat mass (3CLAB, 1.3 ± 2.2 kg; 3CFIELD, 1.4 ± 2.2 kg; US, 2.1 ± 2.6 kg; BIA, 1.4 ± 2.9 kg) were detected by all methods. However, only the 3CFIELD model demonstrated equivalence with the 3CLAB model. In addition, the 3CFIELD model exhibited superior performance to US and BIA individually, as indicated by the total error (3CFIELD, 1.0 kg; US, 1.8 kg; BIA, 1.6 kg), 95% limits of agreement (3CFIELD, ±2.1 kg; US, ±3.3 kg; BIA, ±3.1 kg), correlation coefficients (3CFIELD, 0.79-0.82; US, 0.49-0.55; BIA, 0.61-0.72), and additional metrics., Conclusions: The present study demonstrated the potential usefulness of a 3CFIELD model incorporating US and BIA data for tracking body composition changes over time, as well as its superiority to US or BIA individually. As such, this accessible multicompartment model may be suitable for implementation in field or limited-resource settings., (Copyright © 2020 by the American College of Sports Medicine.)

Abstract: Zanders, BR, Currier, BS, Harty, PS, Zabriskie, HA, Smith, CR, Stecker, RA, Richmond, SR, Jagim, AR, and Kerksick, CM. Changes in energy expenditure, dietary intake, and energy availability across an entire collegiate women's basketball season. J Strength Cond Res 35(3): 804-810, 2021-The purpose of this study was to identify changes in energy expenditure and dietary intake across an entire women's basketball season. On 5 different occasions across the competitive season, female collegiate basketball players (19.8 ± 1.3 years, 173.9 ± 13.6 cm, 74.6 ± 9.1 kg, 27.1 ± 3.2% fat, 53.9 ± 6.4 ml·kg-1·min-1, n = 13) were outfitted with heart rate and activity monitors over 4 consecutive days and completed 4-day food and fluid records to assess changes in energy expenditure and dietary status. Dual-energy x-ray absorptiometry was used to assess baseline body composition and resting energy expenditure (REE) was measured before and after the season. Data were analyzed using 1-factor repeated-measures analysis of variance. Total daily energy expenditure (TDEE, p = 0.059) and physical activity levels (TDEE/REE, p = 0.060) both tended to decrease throughout the season. Energy balance was negative at all time points throughout the season. Absolute and normalized daily protein intake at the end of the season was significantly (p < 0.05) lower than at the beginning of the season. Carbohydrate (3.7 ± 0.4 g·kg-1·d-1) and protein (1.17 ± 0.16 g·kg-1·d-1) intakes were lower than commonly recommended values based on previously published guidelines. These findings suggest that greater education and interventions for collegiate athletes and coaches regarding dietary intake and energy expenditure are warranted., (Copyright © 2018 National Strength and Conditioning Association.)

Background: Large (48-g), isonitrogenous doses of rice and whey protein have previously been shown to stimulate similar adaptations to resistance training, but the impact of consuming smaller doses has yet to be compared. We evaluated the ability of 24-g doses of rice or whey protein concentrate to augment adaptations following 8 weeks of resistance training., Methods: Healthy resistance-trained males (n = 24, 32.8 ± 6.7 years, 179.3 ± 8.5 cm, 87.4 ± 8.5 kg, 27.2 ± 1.9 kg/m 2 , 27.8 ± 6.0% fat) were randomly assigned and matched according to fat-free mass to consume 24-g doses of rice (n = 12, Growing Naturals, LLC) or whey (n = 12, NutraBio Labs, Inc.) protein concentrate for 8 weeks while completing a standardized resistance training program. Body composition (DXA), muscular strength (one-repetition maximum [1RM]) and endurance (repetitions to fatigue [RTF] at 80% 1RM) using bench press (BP) and leg press (LP) exercises along with anaerobic capacity (Wingate) were assessed before and after the intervention. Subjects were asked to maintain regular dietary habits and record dietary intake every 2 weeks. Outcomes were assessed using 2 × 2 mixed (group x time) factorial ANOVA with repeated measures on time and independent samples t-tests using the change scores from baseline. A p-value of 0.05 and 95% confidence intervals on the changes between groups were used to determine outcomes., Results: No baseline differences (p > 0.05) were found for key body composition and performance outcomes. No changes (p > 0.05) in dietary status occurred within or between groups (34 ± 4 kcal/kg/day, 3.7 ± 0.77 g/kg/day, 1.31 ± 0.28 g/kg/day, 1.87 ± 0.23 g/kg/day) throughout the study for daily relative energy (34 ± 4 kcals/kg/day), carbohydrate (3.7 ± 0.77 g/kg/day), fat (1.31 ± 0.28 g/kg/day), and protein (1.87 ± 0.23 g/kg/day) intake. Significant main effects for time were revealed for body mass (p = 0.02), total body water (p = 0.01), lean mass (p = 0.008), fat-free mass (p = 0.007), BP 1RM (p = 0.02), BP volume (p = 0.04), and LP 1RM (p = 0.01). Changes between groups were similar for body mass (- 0.88, 2.03 kg, p = 0.42), fat-free mass (- 0.68, 1.99 kg, p = 0.32), lean mass (- 0.73, 1.91 kg, p = 0.37), fat mass (- 0.48, 1.02 kg, p = 0.46), and % fat (- 0.63, 0.71%, p = 0.90). No significant between group differences were seen for BP 1RM (- 13.8, 7.1 kg, p = 0.51), LP 1RM (- 38.8, 49.6 kg, p = 0.80), BP RTF (- 2.02, 0.35 reps, p = 0.16), LP RTF (- 1.7, 3.3 reps, p = 0.50), and Wingate peak power (- 72.5, 53.4 watts, p = 0.76) following the eight-week supplementation period., Conclusions: Eight weeks of daily isonitrogenous 24-g doses of rice or whey protein in combination with an eight-week resistance training program led to similar changes in body composition and performance outcomes. Retroactively registered on as NCT04411173 .

Little is known about the optimal time to consume caffeine prior to exercise to maximize the ergogenic benefits of the substance. Purpose: To determine the optimal pre-exercise time interval to consume caffeine to improve lower-body muscular performance. A secondary aim was to identify the presence of any sex differences in responses to timed caffeine administration. Methods: Healthy, resistance-trained males ( n = 18; Mean±SD; Age: 25.1 ± 5.7 years; Height: 178.4 ± 7.1 cm; Body mass: 91.3 ± 13.5 kg; Percent body fat: 20.7 ± 5.2; Average caffeine consumption: 146.6 ± 100.3 mg/day) and females ( n = 11; Mean ± SD; Age: 20.1 ± 1.6 years; Height: 165.0 ± 8.8 cm; Body mass: 65.8 ± 10.0 kg; Percent bodyfat: 25.8 ± 4.2; Average caffeine consumption: 111.8 ± 91.7 mg/day) participated in this investigation. In a randomized, double-blind, placebo-controlled, crossover fashion, participants consumed 6 mg·kg -1 caffeine or placebo solution at three time points: 2 h prior (2H), 1 h prior (1H), or 30 min prior (30M) to exercise testing. During three visits, caffeine was randomly administered at one time point, and placebo was administered at the other two time points. During one visit, placebo was administered at all three time points. Next, participants performed isometric mid-thigh pulls (IMTP), countermovement vertical jumps (CMVJ), and isometric/isokinetic knee extensor testing (ISO/ISOK). Results: Caffeine administered at 1H significantly improved absolute CMVJ and ISO performance relative to placebo. Mean CMVJ jump height was significantly higher during 1H compared to 30M. However, only caffeine administered at 30M significantly improved absolute measures of isokinetic performance. Analysis of the pooled caffeine conditions revealed that muscular performance was more consistently augmented by caffeine in males compared to females. Conclusions: Pre-exercise caffeine timing significantly modulated participant responses to the substance, with 1H exerting the most consistent ergogenic benefits relative to other time points, particularly compared to 2H. Male participants were found to respond more consistently to caffeine compared to female participants. These results suggest that active individuals can maximize the ergogenic effects of caffeine by consuming the substance ~1 h prior to the point when peak muscular performance is desired., (Copyright © 2020 Harty, Zabriskie, Stecker, Currier, Tinsley, Surowiec, Jagim, Richmond and Kerksick.)

An amendment to this paper has been published and can be accessed via the original article.

Common body composition estimation techniques necessitate assumptions of uniform fat-free mass (FFM) characteristics, although variation due to sex, race, and body characteristics may occur. National Health and Nutrition Examination Survey data from 1999 to 2004, during which paired dual-energy x-ray absorptiometry (DXA) and bioimpedance spectroscopy assessments were performed, were used to estimate FFM characteristics in a sample of 4619 US adults. Calculated FFM characteristics included the density and water, bone mineral, and residual content of FFM. A rapid 4-component model was also produced using DXA and bioimpedance spectroscopy data. Study variables were compared across sex, race/ethnicity, body mass index (BMI), and age categories using multiple pairwise comparisons. A general linear model was used to estimate body composition after controlling for other variables. Statistical analyses accounted for 6-year sampling weights and complex sampling design of the National Health and Nutrition Examination Survey and were based on 5 multiply imputed datasets. Differences in FFM characteristics across sex, race, and BMI were observed, with notable dissimilarities between men and women for all outcome variables. In racial/ethnic comparisons, non-Hispanic blacks most commonly presented distinct FFM characteristics relative to other groups, including greater FFM density and proportion of bone mineral. Body composition errors between DXA and the 4-component model were significantly influenced by sex, age, race, and BMI. In conclusion, FFM characteristics, which are often assumed in body composition estimation methods, vary due to sex, race/ethnicity, and weight status. The variation of FFM characteristics in diverse populations should be considered when body composition is evaluated., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: Energy drinks are often consumed by the general population, as well as by active individuals seeking to enhance exercise performance and augment training adaptations. However, limited information is available regarding the efficacy of these products. Thus, the purpose of this study was to determine the effects of a commercially available caffeine- and protein-containing energy drink on metabolism and muscular performance., Methods: Sixteen resistance-trained males (n = 8; mean ± SD; age: 22.4 ± 4.9 years; body mass: 78.8 ± 14.0 kg; body fat: 15.3 ± 6.4%) and females (n = 8; age: 24.5 ± 4.8 years; body mass: 67.5 ± 11.9 kg; body fat: 26.6 ± 7.1%) participated in this randomized, double-blind, placebo-controlled, crossover study. Following a familiarization visit, participants completed two identical visits to the laboratory separated by 5-10 days, each of which consisted of indirect calorimetry energy expenditure (EE) assessments before and after consumption of the beverage (Bang® Keto Coffee; 130 kcal, 300 mg caffeine, 20 g protein) or placebo (30 kcal, 11 mg caffeine, 1 g protein) as well as after exercise testing. In addition, participants' subjective feelings of energy, fatigue, and focus as well as muscular performance (leg press one-repetition maximum and repetitions to fatigue, maximal isometric and isokinetic squat testing) were assessed. Multiple repeated measures ANOVAs with Tukey post-hoc tests were used to analyze data. Estimates of effect size were quantified via partial eta squared (η P 2 ) and Hedge's g., Results: A significant interaction effect was identified for EE (p < 0.001, η P 2  = 0.52) but not respiratory exchange ratio (p = 0.17, η P 2  = 0.11). Following consumption of the beverage, EE was 0.18 [corrected]  kcal·min - 1 greater than placebo at the post-beverage time point (p < 0.001) and 0.08 [corrected]  kcal·min - 1 greater than placebo at the post-exercise time point (p = 0.011). However, no between-condition differences were detected for any subjective or muscular performance outcomes., Conclusions: The results of this study suggest that consumption of the energy drink had minimal effects on lower-body muscular performance and subjective factors in the context of a laboratory setting. However, the beverage was found to significantly increase energy expenditure compared to placebo immediately following ingestion as well as during the recovery period after an exercise bout, suggesting that active individuals may improve acute metabolic outcomes via consumption of a caffeine- and protein-containing energy drink., Trial Registration: This trial was prospectively registered at ClinicalTrials.gov (Identifier: NCT04180787 ; Registered 29 November 2019).

Objective: To examine differences in the frequency and severity of federally reported adverse events between caffeine-containing and non-caffeine-containing products while also identifying the category of caffeine-containing products associated with the highest frequency and severity of adverse events., Patients and Methods: All adverse event reports that met specified eligibility criteria and were submitted to the Center for Food Safety and Applied Nutrition Adverse Event Reporting System between January 1, 2014, and June 29, 2018, were extracted. In this retrospective observational study, the most severe adverse event experienced, an ordinal variable, was categorized into death, life-threatening, hospitalization/disability, and emergency department visit. A nonproportional odds model was used to compare the odds of caffeine-containing products being associated with more severe adverse events relative to a noncaffeine group. The analysis is of data only from those reporting adverse events and may or may not be representative of the entire population exposed to these products, which is not known from the examined data., Results: Energy and preworkout products saw a significant increase in the odds of the adverse event experienced being death rather than the other less severe outcomes relative to the noncaffeinated group. Those products, along with weight loss products, had greater odds of the adverse event being death or life-threatening vs the less severe outcomes relative to the noncaffeinated group., Conclusion: Caffeine-containing products have a greater association with severe adverse events compared with non-caffeine-containing products. Exposure to preworkout and weight loss products had greater odds of being associated with a more serious adverse event relative to noncaffeinated products. Health care practitioners should use these outcomes to better inform and educate patients about the many factors related to caffeine intake and adverse outcomes., (Copyright © 2020 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.)

Estimates of body composition have been derived using 3-dimensional optical imaging (3DO), but no equations to date have been calibrated using a 4-component (4C) model criterion. This investigation reports the development of a novel body fat prediction formula using anthropometric data from 3DO imaging and a 4C model. Anthropometric characteristics and body composition of 179 participants were measured via 3DO (Size Stream ® SS20) and a 4C model. Machine learning was used to identify significant anthropometric predictors of body fat (BF%), and stepwise/lasso regression analyses were employed to develop new 3DO-derived BF% prediction equations. The combined equation was externally cross-validated using paired 3DO and DXA assessments (n = 158), producing a R 2 value of 0.78 and a constant error of (X ± SD) 0.8 ± 4.5%. 3DO BF% estimates demonstrated equivalence with DXA based on equivalence testing with no proportional bias in the Bland-Altman analysis. Machine learning methods may hold potential for enhancing 3DO-derived BF% estimates.

Aerobic exercise and thermal stress instigate robust challenges to the immune system. Various attempts to modify or supplement the diet have been proposed to bolster the immune system responses. The purpose of this study was to identify the impact of yeast beta-glucan ( Saccharomyces cerevisiae ) supplementation on exercise-induced muscle damage and inflammation. Healthy, active men (29.6 ± 6.7 years, 178.1 ± 7.2 cm, 83.2 ± 11.2 kg, 49.6 ± 5.1 mL/kg/min, n = 16) and women (30.1 ± 8.9 years, 165.6 ± 4.1 cm, 66.7 ± 10.0 kg, 38.7 ± 5.8 mL/kg/min, n = 15) were randomly assigned in a double-blind and cross-over fashion to supplement for 13 days with either 250 mg/day of yeast beta-glucan (YBG) or a maltodextrin placebo (PLA). Participants arrived fasted and completed a bout of treadmill exercise at 55% peak aerobic capacity (VO 2Peak ) in a hot (37.2 ± 1.8 °C) and humid (45.2 ± 8.8%) environment. Prior to and 0, 2, and 72 h after completing exercise, changes in white blood cell counts, pro- and anti-inflammatory cytokines, markers of muscle damage, markers of muscle function, soreness, and profile of mood states (POMS) were assessed. In response to exercise and heat, both groups experienced significant increases in white blood cell counts, plasma creatine kinase and myoglobin, and soreness along with reductions in peak torque and total work with no between-group differences. Concentrations of serum pro-inflammatory cytokines in YBG were lower than PLA for macrophage inflammatory protein 1β (MIP-1β) ( p = 0.044) and tended to be lower for interleukin 8 (IL-8) ( p = 0.079), monocyte chemoattractment protein 1 (MCP-1) ( p = 0.095), and tumor necrosis factor α (TNF-α) ( p = 0.085). Paired samples t -tests using delta values between baseline and 72 h post-exercise revealed significant differences between groups for IL-8 ( p = 0.044, 95% Confidence Interval (CI): (0.013, 0.938, d = -0.34), MCP-1 ( p = 0.038, 95% CI: 0.087, 2.942, d = -0.33), and MIP-1β ( p = 0.010, 95% CI: 0.13, 0.85, d = -0.33). POMS outcomes changed across time with anger scores in PLA exhibiting a sharper decline than YBG ( p = 0.04). Vigor scores ( p = 0.04) in YBG remained stable while scores in PLA were significantly reduced 72 h after exercise. In conclusion, a 13-day prophylactic period of supplementation with 250 mg of yeast-derived beta-glucans invoked favorable changes in cytokine markers of inflammation after completing a prolonged bout of heated treadmill exercise.

Background: Raw bioelectrical values can be used to assess physiological outcomes, though limited information is available concerning the relationships between changes in these values and changes in other variables of interest., Methods: This investigation quantified the relationships between total and segmental changes in raw bioelectrical variables (i.e., resistance, reactance, and phase angle) and corresponding whole-body and segmental changes in independently assessed body composition. Resistance-trained females (n = 31, body mass index: 22.8 ± 2.6 kg/m 2 , body fat: 28 ± 6%) completed eight weeks of supervised resistance training. Before and after the intervention, body composition was assessed via dual-energy x-ray absorptiometry (GE® Lunar Prodigy), and raw bioelectrical variables were assessed via 8-point multi-frequency bioelectrical impedance analysis (Seca® mBCA 515/514) at 19 frequencies ranging from 1 to 1000 kHz., Results: Lean soft tissue of the whole body (+ 3.2% [2.1, 4.4]; mean [95% confidence interval]) and each body segment (+ 2.8 to 6.3%) increased as a result of the intervention. Group-level changes in total (- 2.4% [- 5.2, 0.3]) and segmental fat mass were not statistically significant. Significant decreases in total resistance (- 2.1% [- 3.7, - 0.6] at 50 kHz) and increases in phase angle (+ 4.2% [2.5, 5.9] at 50 kHz) were observed, with minimal changes in reactance and varying changes in segmental values. Moderate to strong negative correlations (0.63 ≤ |r| ≤ 0.83, p ≤ 0.001) were found between changes in lean soft tissue and changes in resistance for the whole body, trunk, and arms. No significant correlations were identified between changes in fat mass or bone mineral content and changes in any bioelectrical variable., Conclusions: Total and segmental changes in resistance were associated with corresponding total and segmental changes in lean soft tissue following a resistance training intervention, while fewer associations were identified between changes in other bioelectrical parameters (i.e., reactance and phase angle) and body composition variables (e.g., fat mass and bone mineral content). Measurement frequency and body segment appeared to influence the presence and strength relationships between bioelectrical and body composition variables. These findings suggest that researchers and practitioners utilizing bioimpedance technology may benefit from examining raw resistance values to enhance detection of physiological adaptations to exercise interventions.

Beta-alanine (BA) is a precursor to carnosine which functions as a buffer assisting in the maintenance of intracellular pH during high-intensity efforts. Rugby is a sport characterized by multiple intermittent periods of maximal or near maximal efforts with short periods of rest/active recovery. The purpose of this pilot study was to evaluate the impact of six weeks of beta-alanine supplementation on anaerobic performance measures in collegiate rugby players. Twenty-one male, collegiate rugby players were recruited, while fifteen completed post-testing (Mean ± SD; Age: 21.0 ± 1.8 years, Height: 179 ± 6.3 cm, Body Mass: 91.8 ± 13.3 kg, % Body Fat: 21.3 ± 4.4). Supplementation was randomized in a double-blind, placebo-controlled manner between 6.4 g/d of beta-alanine and 6.4 g/d of maltodextrin placebo. Body composition, upper and lower-body maximal strength and muscular endurance, intermittent sprint performance, and post-exercise lactate, heart rate, and rating of perceived exertion were assessed before and after supplementation. Data were analyzed using a 2 × 2 (group × time) mixed factorial analysis of variance (ANOVA) with repeated measures on time. No significant interaction effects were noted for body mass, fat mass, fat-free mass, and percent bodyfat ( p > 0.05). No performance effects resulting from beta-alanine supplementation were detected. Results from this initial pilot investigation suggest that BA exerts little to no impact on body composition parameters, muscular strength, muscular endurance, or intermittent sprinting performance. With the limited research exploring the impact of BA in this sporting context, these initial findings offer little support for BA use, but more research is needed to fully understand the potential impact of BA on various aspects of resistance exercise performance.

Background: The purpose of this study was to compare nutritional intakes against recommended values as well as between the perceived intake and needs of female lacrosse players., Methods: Twenty female NCAA Division II lacrosse players (20.0 ± 1.7 yrs., 169.7 ± 6.4 cm; 69.9 ± 10.7 kg; 27.5 ± 3.3% fat) completed a four-day monitoring period during in-season. Athletes were outfitted with an activity monitor over four consecutive days and completed four-day food records to assess total daily energy expenditure (TDEE) and dietary intake. Body composition was assessed and used to calculate recommended dietary intakes. Actual intake was self-reported using a commercially available food tracking program (MyFitnessPal©, USA). Daily average values were calculated for total and relative energy, protein, carbohydrate, and fat intake. These values were then compared to published nutritional recommendations established by the International Society of Sports Nutrition. Appropriate pairwise comparisons were made depending on the normality of the distribution., Results: Athletes ate significantly less than recommended values for energy, carbohydrates and protein. (p < 0.001). Significant discrepancies (p < 0.001) were also observed between perceptions of intake versus actual intake., Conclusions: Athletes significantly underestimated perceived intake of dietary fat and carbohydrate when compared to perceived needs. Massive standard deviations and ranges were observed, suggesting that some athletes lack a basic understanding of their daily needs. Results from this data suggest that collegiate athletes lack appropriate understanding of basic nutrition needs and could benefit from basic nutrition education as it pertains to their health and performance.

Fat-free mass index (FFMI) is a height-adjusted metric of fat-free mass which has been suggested as a useful method of body composition assessment in athletic populations. The purpose of this study was to determine sport-specific FFMI values and the natural upper threshold of FFMI in female athletes. 372 female collegiate athletes (Mean±SD; 20.03±1.55 years, 167.55±7.50 cm, 69.46±13.04 kg, 24.18±5.48% bodyfat) underwent body composition assessment via dual-energy x-ray absorptiometry. FFMI was adjusted to height via linear regression and sport-specific reference values were determined. Between-sport differences were identified using one-way ANOVA with Tukey post-hoc tests. Average FFMI was 18.82±2.08 kg/m 2 ; height-adjusted values were not significantly different (p<0.05) than unadjusted values. FFMI in rugby athletes (20.09±2.23 kg/m 2 ) was found to be significantly higher (p<0.05) than in gymnastics (18.62±1.12 kg/m 2 ), ice hockey (17.96±1.04 kg/m 2 ), lacrosse (18.58±1.84 kg/m 2 ), swim & dive (18.16±1.67 kg/m 2 ), and volleyball (18.04±1.13 kg/m 2 ). FFMI in cross country (16.56±1.14 kg/m 2 ) and synchronized swimming (17.27±1.47 kg/m 2 ) was significantly lower (p<0.05) than in Olympic weightlifting (19.69±1.98 kg/m 2 ), wrestling (19.15±2.47 kg/m 2 ), and rugby. The upper threshold for FFMI in female athletes (97.5 th percentile) was 23.90 kg/m 2 . These results can be used to guide personnel decisions and assist with long-term body composition, training, and nutritional goals.

The timing of macronutrient ingestion in relation to exercise is a purported strategy to augment muscle accretion, muscle and athletic performance, and recovery. To date, the majority of macronutrient nutrient timing research has focused on carbohydrate and protein intake. However, emerging research suggests that the strategic ingestion of various ergogenic aids and micronutrients may also have beneficial effects. Therefore, the purpose of this narrative review is to critically evaluate and summarize the available literature examining the timing of ergogenic aids (caffeine, creatine, nitrates, sodium bicarbonate, beta-alanine) and micronutrients (iron, calcium) on muscle adaptations and exercise performance. In summary, preliminary data is available to indicate the timing of caffeine, nitrates, and creatine monohydrate may impact outcomes such as exercise performance, strength gains and other exercise training adaptations. Furthermore, data is available to suggest that timing the administration of beta-alanine and sodium bicarbonate may help to minimize known untoward adverse events while maintaining potential ergogenic outcomes. Finally, limited data indicates that timed ingestion of calcium and iron may help with the uptake and metabolism of these nutrients. While encouraging, much more research is needed to better understand how timed administration of these nutrients and others may impact performance, health, or other exercise training outcomes.

Currier, BS, Harty, PS, Zabriskie, HA, Stecker, RA, Moon, JM, Jagim, AR, and Kerksick, CM. Fat-free mass index in a diverse sample of male collegiate athletes. J Strength Cond Res 33(6): 1474-1479, 2019-Fat-free mass index (FFMI) is a body composition metric that has been used to assess relative muscularity in athletes. Fat-free mass index is calculated by dividing FFM by height squared, although further height corrections through linear regression may be needed in taller individuals. This study reported height-adjusted FFMI (FFMIAdj) data in 209 male collegiate athletes from 10 sports (baseball, cross country, football, golf, ice hockey, weightlifting, rugby, swimming, track and field, and water polo) and the FFMIAdj natural upper limit for sports with sufficient sample size. The body composition of all subjects (mean ± SD; age: 20.7 ± 1.9 years, height: 182.9 ± 6.7 cm, body mass: 90.8 ± 16.8 kg, and percent body fat: 15.6 ± 5.3) was measured using dual-energy x-ray absorptiometry. Linear regression was used to adjust for height, and the FFMIAdj natural upper limit was determined by calculating the 97.5th percentile of all values. One-way analyses of variance with Games-Howell post hoc comparisons were used to determine between-sport differences. A paired-samples t-test revealed a significant difference (p < 0.001) between unadjusted and adjusted mean FFMI values. The overall mean FFMIAdj was 22.8 ± 2.8 kg·m. Significant between-sport differences (p < 0.001) in FFMIAdj were identified. Average FFMIAdj was highest in football athletes (24.28 ± 2.39 kg·m) and lowest in water polo athletes (20.68 ± 3.56 kg·m). The FFMIAdj upper limit was calculated for all athletes (28.32 kg·m), rugby (29.1 kg·m), and baseball (25.5 kg·m). This study reported FFMIAdj values in a diverse cohort of male collegiate athletes, providing data for the first time in several sports. These values can be used to guide nutritional and exercise interventions, predict athletic performance, and provide coaches with standardized information regarding the potential for further FFM accretion in male athletes.

The purpose of the present study was to examine characteristics of multi-ingredient pre-workout supplement (MIPS) users, their common patterns/habits of MIPS ingestion, and their associated feelings about the effectiveness and safety of this class of supplements. An online electronic survey was distributed through social media to assess self-reported supplementation practices and preferences among adult males and females who reported regular MIPS use. A total of 1045 individuals responded, with 872 of these individuals (males: n = 636, 72.9%; females: n = 233, 26.7%; mean ± SD; age = 27.7 ± 7.9 years; training age = 8.2 ± 7.3 years) completing the survey. The majority of respondents reported the length of current or past MIPS consumption as greater than one year ( n = 630, 72.2%), with ingestion frequencies primarily of four ( n = 210, 24.1%) or five ( n = 212, 24.3%) days per week of training. In addition, the three most popular goals for ingesting MIPS were increased energy and focus ( n = 776, 89.0%), muscular endurance ( n = 325, 37.3%), and blood flow or "pump" ( n = 322, 37.0%). Although most users reported ingesting one serving size with each use, 14% reported ingesting two or more, and 18% indicated they ingest MIPS more than once per day. Importantly, over half (54%) of the respondents reported experiencing side-effects following MIPS use, including skin reactions, heart abnormalities, and nausea. Females were more likely than males to experience these side effects, despite being less likely to consume two or more serving sizes per dose. Our findings also indicated that MIPS users should consume no more than the recommended serving size of a given supplement, as the potentially significant variability in the caffeine content of MIPS products is compounded as more doses are consumed. Furthermore, MIPS users should minimize the ingestion of other supplements which contain high levels of niacin and caffeine, as the concurrent consumption of such products may put users above the tolerable upper limits for these substances.

Little data is available regarding the energy and nutritional status of female collegiate team sport athletes. Twenty female NCAA Division II lacrosse athletes (mean ± SD: 20.4 ± 1.8 years; 68.8 ± 8.9 kg; 168.4 ± 6.6 cm; 27.9 ± 3% body fat) recorded dietary intake and wore a physical activity monitor over four consecutive days at five different time points (20 days total) during one academic year. Body composition, bone health, and resting metabolic rate were assessed in conjunction with wearing the monitor during off-season, pre-season, and season-play. Body fat percentage decreased slightly during the course of this study ( p = 0.037). Total daily energy expenditure (TDEE) ( p < 0.001) and activity energy expenditure (AEE) ( p = 0.001) energy were found to change significantly over the course of the year, with pre-season training resulting in the highest energy expenditures (TDEE: 2789 ± 391 kcal/day; AEE: 1001 ± 267 kcal/day). Caloric (2124 ± 448 kcal/day), carbohydrate (3.6 ± 1.1 g/kg), and protein (1.2 ± 0.3 g/kg) intake did not change over the course of the year ( p > 0.05). Athletes self-reported a moderate negative energy balance (366⁻719 kcal/day) and low energy availability (22.9⁻30.4 kcal/kg FFM) at each measurement period throughout the study. Reported caloric and macronutrient intake was low given the recorded energy expenditure and macronutrient intake recommendations for athletes. Athletic support staff should provide athletes with appropriate fueling strategies, particularly during pre-season training, to adequately meet energy demands.

Multi-ingredient pre-workout supplements are a popular class of dietary supplements which are purported to improve exercise performance. However, the composition of these products varies substantially between formulations, thus making comparisons challenging. Therefore, the purpose of this study was to identify a common ingredient profile of top-selling pre-workout supplements and to compare ingredient dosages to established efficacious values. The top 100 commercially available pre-workout products were analyzed for listed ingredients and amounts, if available, from the supplement facts panel. The mean ± SD number of ingredients per supplement ( n = 100) was 18.4 ± 9.7 with 8.1 ± 9.9 of these ingredients included in a proprietary blend at undisclosed quantities. Relative prevalence and average amounts of the top ingredients amounted to: Beta-alanine (87%; 2.0 ± 0.8 g), Caffeine (86%; 254.0 ± 79.5 mg), Citrulline (71%; 4.0 ± 2.5 g), Tyrosine (63%; 348.0 ± 305.7 mg), Taurine (51%; 1.3 ± 0.6 g), and Creatine (49%; 2.1 ± 1.0 g). Nearly half (44.3%) of all ingredients were included as part of a proprietary blend with undisclosed amounts of each ingredient. The average amount of beta-alanine per serving size was below the recommended efficacious dose. The average caffeine content was near the low end for an effective relative dose for a 70 kg individual (3⁻6 mg·kg -1 of bodyweight).

Exercise-induced muscle damage (EIMD) is typically caused by unaccustomed exercise and results in pain, soreness, inflammation, and reduced muscle function. These negative outcomes may cause discomfort and impair subsequent athletic performance or training quality, particularly in individuals who have limited time to recover between training sessions or competitions. In recent years, a multitude of techniques including massage, cryotherapy, and stretching have been employed to combat the signs and symptoms of EIMD, with mixed results. Likewise, many varied nutritional and supplementation interventions intended to treat EIMD-related outcomes have gained prominence in the literature. To date, several review articles have been published that explore the many recovery strategies purported to minimize indirect markers of muscle damage. However, these articles are very limited from a nutritional standpoint. Thus, the purpose of this review is to briefly and comprehensively summarize many of these strategies that have been shown to positively influence the recovery process after damaging exercise. These strategies have been organized into the following sections based on nutrient source: fruits and fruit-derived supplements, vegetables and plant-derived supplements, herbs and herbal supplements, amino acid and protein supplements, vitamin supplements, and other supplements.

Background: Augmenting fat oxidation is a primary goal of fitness enthusiasts and individuals desiring to improve their body composition. Performing aerobic exercise while fasted continues to be a popular strategy to achieve this outcome, yet little research has examined how nutritional manipulations influence energy expenditure and/or fat oxidation during and after exercise. Initial research has indicated that pre-exercise protein feeding may facilitate fat oxidation while minimizing protein degradation during exercise, but more research is needed to determine if the source of protein further influences such outcomes., Methods: Eleven healthy, college-aged males (23.5 ± 2.1 years, 86.0 ± 15.6 kg, 184 ± 10.3 cm, 19.7 ± 4.4%fat) completed four testing sessions in a randomized, counter-balanced, crossover fashion after observing an 8-10 h fast. During each visit, baseline substrate oxidation and resting energy expenditure (REE) were assessed via indirect calorimetry. Participants ingested isovolumetric, solutions containing 25 g of whey protein isolate (WPI), 25 g of casein protein (CAS), 25 g of maltodextrin (MAL), or non-caloric control (CON). After 30 min, participants performed 30 min of treadmill exercise at 55-60% heart rate reserve. Substrate oxidation and energy expenditure were re-assessed during exercise and 15 min after exercise., Results: Delta scores comparing the change in REE were normalized to body mass and a significant group x time interaction (p = 0.002) was found. Post-hoc comparisons indicated the within-group changes in REE following consumption of WPI (3.41 ± 1.63 kcal/kg) and CAS (3.39 ± 0.82 kcal/kg) were significantly greater (p < 0.05) than following consumption of MAL (1.57 ± 0.99 kcal/kg) and tended to be greater than the non-caloric control group (2.00 ± 1.91 kcal/kg, p = 0.055 vs. WPI and p = 0.061 vs. CAS). Respiratory exchange ratio following consumption of WPI and CAS significantly decreased during the post exercise period while no change was observed for the other groups. Fat oxidation during exercise was calculated and increased in all groups throughout exercise. CAS was found to oxidize significantly more fat (p < 0.05) than WPI during minutes 10-15 (CAS: 2.28 ± 0.38 g; WPI: 1.7 ± 0.60 g) and 25-30 (CAS: 3.03 ± 0.55 g; WPI: 2.24 ± 0.50 g) of the exercise bout., Conclusions: Protein consumption before fasted moderate-intensity treadmill exercise significantly increased post-exercise energy expenditure compared to maltodextrin ingestion and tended to be greater than control. Post-exercise fat oxidation was improved following protein ingestion. Throughout exercise, fasting (control) did not yield more fat oxidation versus carbohydrate or protein, while casein protein allowed for more fat oxidation than whey. These results indicate rates of energy expenditure and fat oxidation can be modulated after CAS protein consumption prior to moderate-intensity cardiovascular exercise and that fasting did not lead to more fat oxidation during or after exercise.

Creatine has been extensively researched and is well-supported as one of the most effective dietary supplements available. There is overwhelming support within the literature regarding the ability of creatine to augment performance following short term (5-7 days) and long-duration supplementation periods. There is also strong support for creatine regarding its safety profile and minimal risk for adverse events or any negative influence on markers of clinical health and safety. Recent research has also highlighted the ability of creatine to confer several health-related benefits in select clinical populations in addition to offering cognitive benefits. Creatine is also a popular supplement of choice for adolescent athletes; however, research in this area is extremely limited, particularly when examining the safety and efficacy of creatine supplementation in this population. Therefore, the purpose of this review was to highlight the limited number of studies available in adolescent populations and systematically discuss the topic of safety of creatine supplementation in a younger population.

In recent years, a new class of dietary supplements called multi-ingredient pre-workout supplements (MIPS) has increased in popularity. These supplements are intended to be taken prior to exercise and typically contain a blend of ingredients such as caffeine, creatine, beta-alanine, amino acids, and nitric oxide agents, the combination of which may elicit a synergistic effect on acute exercise performance and subsequent training adaptations compared to single ingredients alone. Therefore, the purpose of this article was to review the theoretical rationale and available scientific evidence assessing the potential ergogenic value of acute and chronic ingestion of MIPS, to address potential safety concerns surrounding MIPS supplementation, and to highlight potential areas for future research. Though direct comparisons between formulations of MIPS or between a MIPS and a single ingredient are challenging and often impossible due to the widespread use of "proprietary blends" that do not disclose specific amounts of ingredients in a given formulation, a substantial body of evidence suggests that the acute pre-exercise consumption of MIPS may positively influence muscular endurance and subjective mood, though mixed results have been reported regarding the acute effect of MIPS on force and power production. The chronic consumption of MIPS in conjunction with a periodized resistance training program appears to augment beneficial changes in body composition through increased lean mass accretion. However, the impact of long-term MIPS supplementation on force production, muscular endurance, aerobic performance, and subjective measures is less clear. MIPS ingestion appears to be relatively safe, though most studies that have assessed the safety of MIPS are relatively short (less than eight weeks) and thus more information is needed regarding the safety of long-term supplementation. As with any dietary supplement, the use of MIPS carries implications for the athlete, as many formulations may intentionally contain banned substances as ingredients or unintentionally as contaminants. We suggest that athletes thoroughly investigate the ingredients present in a given MIPS prior to consumption. In conclusion, it appears that multi-ingredient pre-workout supplements have promise as an ergogenic aid for active individuals, though further information is required regarding long-term efficacy and safety in a wider variety of populations.

Position Statement: The International Society of Sports Nutrition (ISSN) bases the following position stand on an analysis of the literature regarding the effects of β-Hydroxy-β-Methylbutyrate (HMB). The following 12 points have been approved by the Research Committee of the Society: 1. HMB is a metabolite of the amino acid leucine that is naturally produced in both humans and other animals. Two forms of HMB have been studied: Calcium HMB (HMB-Ca) and a free acid form of HMB (HMB-FA). HMB-FA appears to lead to increased appearance of HMB in the bloodstream when compared to HMB-Ca, though recent results are mixed. 2. The available safety/toxicity data suggest that chronic HMB-Ca and HMB-FA consumption are safe for oral HMB supplementation in humans up to at least one year. 3. There are no negative effects of HMB-Ca and HMB-FA on glucose tolerance and insulin sensitivity in humans. There may be improvements in glucose metabolism in younger adults. 4. The primary mode of action of HMB appears to be through its dual mechanism to enhance muscle protein synthesis and suppress muscle protein breakdown. HMB's activation of mTORC1 is independent of the leucine-sensing pathway (Sestrin2-GATOR2 complex). 5. HMB may help reduce muscle damage and promote muscle recovery, which can promote muscle growth/repair. HMB may also have anti-inflammatory effects, which could contribute to reducing muscle damage and soreness. 6. HMB consumption in close proximity to an exercise bout may be beneficial to increase muscle protein synthesis and attenuate the inflammatory response. HMB can provide a beneficial physiological effect when consumed both acutely and chronically in humans. 7. Daily HMB supplementation (38 mg/kg body weight) in combination with exercise training may improve body composition through increasing lean mass and/or decreasing fat mass with benefits in participants across age, sex, and training status. The most pronounced of these improvements in body composition with HMB have been observed in studies with robust resistance training programs and dietary control. 8. HMB may improve strength and power in untrained individuals, but its performance benefits in trained athletes are mixed and increase with an increase in study duration (>6 weeks). HMB's beneficial effects on athletic performance are thought to be driven by improved recovery. 9. HMB supplementation appears to potentially have a positive impact on aerobic performance, especially in trained athletes. The mechanisms of the effects are unknown. 10. HMB supplementation may be important in a non-exercising sedentary and aging population to improve muscle strength, functionality, and muscle quality. The effects of HMB supplementation with exercise are varied, but the combination may have a beneficial effect on the treatment of age-associated sarcopenia under select conditions. 11. HMB may be effective in countering muscle disuse atrophy during periods of inactivity due to illness or injury. The modulation of mitochondrial dynamics and lipid metabolism by HMB may be a potential mechanism for preventing disuse atrophy and aiding rehabilitation beyond HMB's effects on rates of muscle protein synthesis and degradation. 12. The efficacy of HMB in combination with certain nutrients may be enhanced under select conditions.