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Szeszulski, J, Lorenzo, E, Arriola, A, and Lee, RE. Community-based measurement of body composition in hispanic women: concurrent validity of dual- and single-frequency bioelectrical impedance. J Strength Cond Res 36(2): 577–584, 2022—We examined the concurrent validity of single-frequency (SF) and dual-frequency (DF) bioelectrical impedance (BIA) scales among Hispanic women participating in a community-based health promotion program in Arizona. Hispanic women (N = 14), age 31.9 ± 6.5 years old, with a mean body mass index (BMI) of 31.1 ± 8.1 kg·m−2, were measured using SF BIA, DF BIA, BMI, and skinfold calipers in 2017. Intrarater reliability and concurrent validity were calculated. Bland-Altman plots examined agreement of each BIA measure within measurement tools, between tools, and with skinfold calipers. Scatter plots were used to examine agreement between BIAs and BMI. Short-term intrarater reliability was perfect within measurements for SF and DF BIAs (α = 1.0). The coefficient of variation within a measurement tool (CV%) was slightly smaller for DF BIA (0.2%; n = 13) than for SF BIA (0.3%; n = 14). Concurrent validity measures revealed that DF (M = 39.3 ± 7.3% fat; within sample CV% = 18.6; n = 14) and SF (M = 39.4 ± 7.5% body fat; within sample CV% = 19.0; n = 14) BIAs were highly correlated (Pearson r = 0.885; p < 0.001; n = 14) and had an absolute mean difference of −0.2 ± 3.5% fat (range 0.7–6.0% fat; n = 14). The CV% between BIA measures was 5.4%. Dual-frequency and SF BIAs were both strongly correlated with BMI and skinfolds. There was evidence of bias between skinfolds and both BIA measures. Strength and conditioning practitioners should feel confident in using either SF or DF BIA measures with Hispanic women who participate in training interventions in community-based settings, because they offer similar measurement value. [ABSTRACT FROM AUTHOR]

Walker, EJ, Aughey, RJ, McLaughlin, P, and McAinch, AJ. Seasonal change in body composition and physique of team sport athletes. J Strength Cond Res 36(2): 565–572, 2022—Body composition of team sport athletes was measured at 3 points across the preseason and competitive season. This repeated-measures study was conducted in 46 professional Australian football (AF) (age 23.8 ± 3.8 years), 26 soccer (age 22.7 ± 4.7 years), and 33 rugby union players (age 28.1 ± 4.2 years). A mixed-design analysis of variance was used to determine change across the season, and Pearson's correlation was used to determine the relationship between different measures. Anthropometry, dual-energy x-ray absorptiometry (DXA), and 3-dimensional (3D) scan technology were used in AF and soccer, whereas only DXA was used in rugby. Body mass remained unchanged for both AF and soccer with gains in lean mass (p < 0.01), from preseason to early in the competitive season. Skinfold measures declined in AF (p < 0.001) and soccer (p < 0.05) across the season, whereas DXA-measured fat mass only declined in soccer (p < 0.01). Rugby backs (p < 0.01) and forwards (p < 0.001) reduced body fat and gained lean mass from preseason to in-season with forwards having greater relative and absolute changes as measured by DXA. 3D technology did not show change across the season. Dual-energy x-ray absorptiometry body fat percent and the sum of skinfold correlation were large (r = 0.74 [ p < 0.001, CI 0.67–0.81]). The greatest change in body composition occurs from the beginning of preseason to the start of competition, with changes returning to baseline levels toward the end of season. Dual-energy x-ray absorptiometry and skinfold measures were moderately correlated, providing a good alternative to track change in subcutaneous fat in AF and soccer athletes. [ABSTRACT FROM AUTHOR]

The National Collegiate Athletic Association’s weight management program allows for the use of skinfold measurements (SF), air displacement plethysmography (ADP), and hydrostatic weighing in the assessment of percent body fat (%BF) and determination of a wrestler’s minimum wrestling weight (MWW). Dual energy x-ray absorptiometry (DXA) and ultrasound (US) may offer alternative assessment methods. The purpose of this study was to examine %BF, MWW, and the lowest allowable weight class as determined by SF, ADP, DXA, and US. Thirty-three college-aged men (20.8 6 1.1 years) participated. Urine specific gravity (Usg) was assessed to ensure proper hydration (1.006 6 0.006). Percent body fat and MWW were then determined using the 4 assessment methods. Each method was significantly different from one another (p, 0.05) with the exception of ADP compared with SF (17.6 6 7.1% vs. 17.4 6 6.3%, p 5 1.000) and DXA compared with US (20.5 6 6.2% vs. 19.2 6 7.5%, p 5 0.124). DXA (68.6 6 7.1 kg) and US (69.3 6 6.0 kg) determined the lowest MWW, whereas those determined by SF (70.8 6 6.8 kg) and ADP (70.9 6 6.6 kg) were significantly greater (p, 0.05). The SEEs for MWW when compared with SF were 3.2, 3.4, and 2.4 kg for ADP, DXA, and US, respectively. Compared with SF, DXA and US would allow wrestlers to certify at a lower weight class 64 and 33% of the time, respectively. When comparing the approved methods (SF and ADP), approximately 50% of subjects would certify at a different weight class depending on the method used. The use of different methods in assessing %BF offer a wide variability in the determination of MWW. [ABSTRACT FROM AUTHOR]

We investigated the effects of a 4-week ad-libitum, nonketogenic, carbohydrate-restricted (<25% of calories) diet (CRD) on cardiometabolic and performance markers in firefighters (FF). Subjects (n = 15) completed 9 sessions (trials 1-3 [familiarization], trials 4-6 [baseline], and trials 7-9 [post-CRD]). Following habitual western diet, anthropometric measures were assessed, glucose tolerance measured, and then completed a graded cycling test, maximal Wingate test, and conducted their FF physical performance assessment (FPPA) to measure performance while metabolic variables and perceptual responses were recorded. Subjects then adhered to a CRD for a 4-week duration and returned for repeat testing. Body fat as measured by BodPod, and 7-site skinfold thickness decreased (p < 0.01), and a decrease was observed in blood pressure (BP) (p < 0.01; ~5 mm Hg) after CRD. There were no differences found for glucose tolerance, but an increase was found for fat oxidation rates (p < 0.01; ~0.07 g·min) and a decrease in carbohydrate oxidation rates across a range of intensities (p < 0.01; ~0.24 g·min). Finally, the 2.41-km run and pull-up performance during the FPPA improved (p < 0.01; ~41 second and 3 repetitions, respectively) and with no differences observed between treatments regarding the Wingate test. To date, this is the first CRD implemented with FF and resulted in decreased fat mass (~2.4 kg), BP, and improvements to performance on the FPPA while preserving high-intensity exercise. These data suggest that a 28-day CRD can benefit markers of health in professional FF without detriments to occupational performance. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare percent fat (% fat) estimates from anthropometric equations using skinfolds (SKF) in women's ice hockey players with estimates obtained from Lunar iDXA. Data were collected on 19 elite female Swedish hockey players (mean age ± SD = 18.4 ± 2.4 years). Four SKF (triceps, abdominal, suprailiac, and thigh) were measured within 2 hours of iDXA assessments. The % fat estimates from iDXA and 4 anthropometric equations were compared using paired t tests, and a 1-way analysis of variance was used to compare % fat estimates from the anthropometric equations. Bland-Altman analyses were used to assess agreement between % fat estimates from SKF and iDXA. The significance level was set a priori at p ≤ 0.05. The % fat estimates from anthropometric equations were significantly lower than those from iDXA (mean ± SD: 26.85 ± 4.93%, p = 0.000). Bland-Altman analyses indicated mean differences of -7.96 to -10.13 percentage points between anthropometric equations and iDXA. Estimates of % fat from anthropometric equations (range: 16.72-18.89%) were within the range reported in earlier studies using the sum of 7 SKF. Thus, SKF offer a reasonable alternative to iDXA for this population but result in underestimates of % fat relative to iDXA. Strength and conditioning coaches should use the same body composition assessment method consistently, and interpret the results with caution, as they are estimates and not true values. [ABSTRACT FROM AUTHOR]

A lack of evidence exists regarding the accuracy of common resting metabolic rate (RMR) prediction equations in athletic female populations. The purpose of this research was to measure RMR in a large cohort of NCAA Division II female athletes and use regression techniques to develop new prediction equations. Sixty-six female athletes from 11 different sports completed this protocol, which included skinfold measurements followed by an RMR assessment using indirect calorimetry. The average RMR was 1,466 ± 150 kcal⋅d-1. Many between-sport differences in body composition were identified, with gymnastics athletes having the lowest body fat percentage (p < 0.05) and basketball athletes having the greatest absolute fat-free mass (p < 0.05). Resting metabolic rate was moderately correlated (p < 0.05) with height (r = 0.52), total mass (r = 0.59), and fat-free mass (r = 0.54). Two equations were developed, both of which were more accurate for this population than other RMR prediction equations. One of the new equations, which used height and body mass as covariates (equation 1), was slightly more accurate than the equation using body composition parameters (equation 2). The new equations were cross-validated using a randomly selected subset (n = 22) of the original sample. The subset did not show statistically different results from the remainder of the sample (n = 44) between equation 1 (p = 0.083) and equation 2 (p = 0.22). Equation 1, which had more easily measurable parameters, exhibited heightened accuracy, which has important implications for implementation among athletes, coaches, and athletic support staff. [ABSTRACT FROM AUTHOR]

In addition to technical, tactical, and psychological skills, performance in playing basketball depends on anthropometry and physical fitness. However, limited information is available regarding such features in women. We hypothesized that anthropometry and physical fitness are associated with female basketball performance, and consequently, performance could be predicted using the results of certain anthropometric measures and fitness tests. Body parameters (age, height, body mass, skinfold thicknesses, limb perimeters, and lengths) were measured. Physical fitness capacities (jumping, agility with and without the ball, and speed) were measured by specific tests. In addition, game performance was assessed using technical statistics (rebounds, assists, and points) and the performance index rating (PIR). Teams ranked better in the regular season had smaller mean fat skinfold thickness and spent less time in the agility tests (T-Drill). Correlation analyses indicated that players with better PIR were older, taller, and had a longer arm span and greater contracted arm perimeter (CAP). Furthermore, those players had better results in the T-Drill test. Multiple regression analysis indicated that combined age, height, CAP, fat skinfold thickness, and time in T-Drill test yielded a strong predictor of PIR per time played. In conclusion, the results of the present study indicate that some anthropometric and physical fitness characteristics of female elite basketball teams and players are highly associated with performance-related parameters. In addition, a regression model has been developed to predict the performance of female basketball players. [ABSTRACT FROM AUTHOR]

Twenty young women (20.3 + 1.5 years, 164 + 6 cm, 68.7 + 13.8 kg) without prior structured resistance training experience were recruited for this study. Body composition (BodPod), compartmental water (Bioelectrical Impedance), 7-site skinfold, and arm and thigh cross-sectional area (CSA) were assessed before and after 8-week training. Performance testing consisted of vertical jump, 3-kg chest pass initial velocity, squat 1RM, and overhead press 1RM. After 2 weeks of familiarization training, subjects were matched for body composition and relative squat strength and randomly assigned to either a high-load (HL: n = 10; 4 sets of 5-7 repetitions) or moderate-load (ML: n = 10; 2 sets of 10-14 repetitions) group that completed 6-7 exercises per day performed to momentary muscular failure. Training was divided into 2 lower and one upper body training sessions per week performed on nonconsecutive days for 8 weeks. There were no statistically significant main effects for group or group x time interactions for any variable assessed. Both HL and ML resulted in similar significant increases in lean body mass (1.5 ± 0.83 kg), lean dry mass (1.32 ± 0.62 kg), thigh CSA (6.6 ± 5.6 cm), vertical jump (2.9 ± 3.2 cm), chest pass velocity (0.334 ± 1.67 m·s), back squat one repetition maximum (1RM) (22.5 ± 8.1 kg), and overhead press (3.0 ± 0.8 kg). High-load group and ML group also both resulted in significant decreases in percent body fat (1.3 ± 1.3%), total body water (0.73 ± 0.70 L), and intracellular water (0.43 ± 0.38 L). The results of this study indicate that both moderate-load and high-load training are effective at improving muscle growth, body composition, strength and power in untrained young women. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare body mass index (BMI)-based body fat percentage (BF%) equations and skinfolds with a 4-compartment (4C) model in men and women. One hundred thirty adults (63 women and 67 men) volunteered to participate (age = 23 ± 5 years). BMI was calculated as weight (kg) divided by height squared (m²). BF% was predicted with the BMI-based equations of Jackson et al. (BMIJA), Deurenberg et al. (BMIDE), Gallagher et al. (BMIGA), Zanovec et al. (BMIZA), Womersley and Durnin (BMIWO), and from 7-site skinfolds using the generalized skinfold equation of Jackson et al. (SF7JP). The 4C model BF% was the criterion and derived from underwater weighing for body volume, dual-energy X-ray absorptiometry for bone mineral content, and bioimpedance spectroscopy for total body water. The constant error (CE) was not significantly different for BMIZA compared with the 4C model (p = 0.74, CE = -0.2%). However, BMIJA, BMIDE, BMIGA, and BMIWO produced significantly higher mean values than the 4C model (all p < 0.001, CEs = 1.8-3.2%), whereas SF7JP was significantly lower (p < 0.001, CE = -4.8%). The standard error of estimate ranged from 3.4 (SF7JP) to 6.4% (BMIJA) while the total error varied from 6.0 (SF7JP) to 7.3% (BMIJA). The 95% limits of agreement were the smallest for SF7JP (±7.2%) and widest for BMIJA (±13.5%). Although the BMI-based equations produced similar group mean values as the 4C model, SF7JP produced the smallest individual errors. Therefore, SF7JP is recommended over the BMI-based equations, but practitioners should consider the associated CE. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare competitive surfers' lower limb power output depending on their competitive level, and to evaluate the association between competition rankings. Twenty competitive surfers were divided according to the competitive level as follows: international (INT) or national (NAT), and competitive ranking (RANK1-50 or RANK51-100). Vertical jump and maximal peak power of the lower limbs were measured. No differences were found between INT and NAT surfers in the anthropometric variables, in the vertical jump, or in lower extremity power; although the NAT group had higher levels on the elasticity index, squat jumps (SJs), and counter movement jumps (CMJs) compared with the INT group. The RANK1-50 group had a lower biceps skinfold (p, 0.01), lower skinfolds in the legs (Front thigh: p ≤ 0.05; medial calf: p, 0.01), lower sum of skinfolds (p ≤ 0.05), higher SJ (p, 0.01), CMJ (p, 0.01), and 15 seconds vertical CMJ (p ≤ 0.05); also, maximal peak power of the right leg (MPPR) and left leg (MPPL) w≤ ere higher in the RANK1-50 group. Moderate to large significant correlations were obtained between the surfers' ranking position and some skinfolds, the sum of skinfolds, and vertical jump. Results demonstrate that surfers' physical performance seems to be an accurate indicator of ranking positioning, also revealing that vertical jump capacity and anthropometric variables play an important role in their competitive performance, which may be important when considering their power training. [ABSTRACT FROM AUTHOR]

Previous research in academy rugby league players has evaluated the development of physical qualities according to chronological age. However, no study has considered the training age, defined as the number of formalized years of strength and conditioning training, of these players. Therefore, the purpose of this study was to present and compare the annual changes in physical qualities of academy rugby league players according to training age. Sixty-one academy players undertook a fitness testing assessment, including anthropometric (height, body mass, sum of 4 skinfolds) and physical (10 and 20 m sprint, 10m momentum, vertical jump, Yo-Yo intermittent recovery test level 1 [Yo-Yo IRTL1], one-repetition maximum [1RM] squat, bench press and prone row) measures at the start of preseason on 2 consecutive annual occasions. Players were categorized into one of 3 training age groups (i.e., 0, 1, or 2 years) and were analyzed using magnitude-based inferences. Almost certain, very likely or likely annual improvements were identified for body mass, 10m momentum, Yo-Yo IRTL1, vertical jump, and all strength measures for the 3 training age groups. When training age groups were compared, 1 year showed possibly or likely lower strength increases than 0 years training age. However, the 2 years training age group demonstrated possibly or likely increased strength changes compared with 1 year. These findings suggest that training age is an important consideration for strength and conditioning practitioners but it is likely to be a combination of chronological age, biological maturity, and training experience alongside dynamic interplayer variability that influences the physical development of academy rugby league players. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the spatiotemporal parameters of trained runners and untrained participants with the same foot strike pattern (rearfoot) during running at controlled speeds. Twenty-one participants were classified in 2 groups according to their training experience: Trained (n = 10, amateur runners with long distance training experience) and Untrained (n = 11, healthy untrained participants). Anthropometric variables were recorded, and the participants performed both a submaximal (between 9 and 15 km·h-1) and a graded exercise running test (from 6 km·h-1 until exhaustion) on a treadmill. Physiological (VO2max, heart rate, running economy [RE], peak speed .) and biomechanical variables (contact and flight times, step rate, and length) were simultaneously registered. Trained runners showed higher step rate and shorter step length than the Untrained group at the same running speeds (between 4 and 7%, p ≤ 0.05) and at the same physiological intensities (between 7 and 11%, p ≤ 0.05). However, there were no differences in contact and flight times between groups. Significant differences (p ≤ 0.05) and large effect sizes (Cohen's d) between groups were found for body mass, sum of 6 skinfolds, VO2max, peak speed, and ventilatory threshold and respiratory compensation threshold speeds. The Trained group also showed a ~7% better RE (ml·kg-0.75·km-1) than the Untrained group. In conclusion, adopting higher step rate and shorter step length may be an adaptive mechanism of the Trained group to reduce injury risk and possibly improve RE. However, contact and flight times were consistent regardless of training level. [ABSTRACT FROM AUTHOR]

The purpose of the study was to describe current levels of musculoskeletal fitness (MSF) in U.S. youth by creating nationally representative age-specific and sex-specific growth curves for handgrip strength (including relative and allometrically scaled handgrip), modified pull-ups, and the plank test. Participants in the National Youth Fitness Survey (n = 1,453) were tested on MSF, aerobic capacity (via submaximal treadmill test), and body composition (body mass index [BMI], waist circumference, and skinfolds). Using LMS regression, age-specific and sex-specific smoothed percentile curves of MSF were created and existing percentiles were used to assign age-specific and sex-specific z-scores for aerobic capacity and body composition. Correlation matrices were created to assess the relationships between z-scores on MSF, aerobic capacity, and body composition. At younger ages (3-10 years), boys scored higher than girls for handgrip strength and modified pull-ups, but not for the plank. By ages 13-15, differences between the boys and girls curves were more pronounced, with boys scoring higher on all tests. Correlations between tests of MSF and aerobic capacity were positive and low-to-moderate in strength. Correlations between tests of MSF and body composition were negative, excluding absolute handgrip strength, which was inversely related to other MSF tests and aerobic capacity but positively associated with body composition. The growth curves herein can be used as normative reference values or a starting point for creating health-related criterion reference standards for these tests. Comparisons with prior national surveys of physical fitness indicate that some components of MSF have likely decreased in the United States over time. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the anthropometric variables that best predict Special Judo Fitness Test (SJFT) performance. In addition, anthropometric profiles of elite Spanish judo athletes were compared by sex and age category (seniors and juniors). In this cross-sectional study, a total of 51 (29 females) athletes from the Spanish National Judo Team were evaluated during a competitive period. All athletes performed the SJFT and underwent an anthropometric assessment through skinfold thickness measurements. Mann-Whitney comparisons by sex and age category showed that males had significantly higher muscle mass and lower fat mass than females (p < 0.001), whereas juniors and seniors exhibited few differences in body composition. Linear regression analyses (stepwise method) were performed to explore the relationships between anthropometric characteristics and SJFT variables. Model 1 included sex, age category, and body mass as predictors. Body mass and sex significantly predicted the SJFT index (R² = 0.27, p < 0.001); thus, both criteria should be considered before interpreting the test. The predictors of model 2 were quick-assessment variables, including skinfolds, breadths, girths, and height. This regression model showed that the biceps skinfold significantly predicted the SJFT index in elite athletes (R² = 0.31, p < 0.001). Model 3 included body compositions and somatotypes as predictors. [ABSTRACT FROM AUTHOR]

The article presents a study which examines time structure, performance, and perceptual responses in jiu-jitsu athletes in Brazil during a simulated competition. The study conducted physical scales and tests of the perception of athletes' recovery and effort. Results showed an unchanged flexibility and reaction among athletes across the competition and the effect of the use of kimono on their grip endurance.

The article discusses research which investigated benefits of combining repeated-sprint and muscle strength training sessions to young soccer players. Topics explored include the physical abilities and tactical skills that are deemed necessary for soccer players, the recruitment and participation of young athletes in an intervention program designed to improve repeated-sprint ability (RSA), and the anthropometric characteristics of study participants such as body mass, skinfolds and height.

The article discusses research which investigated the use of youth rugby league maturity groups in evaluating anthropometric and fitness characteristics of adolescent players. Topics explored include the selection and assignment of study participants in annual maturity groups, the use of a Seca Alpha stadiometer in calculating sitting height of players, and the recording of fitness performance ranging from sprint speed to vertical jumps.

The article discusses research which was conducted to investigate the age related patterns of differences in height, body mass, per cent body fat, body mass index and skin folds in 11 to 18 year old wrestlers. Researchers evaluated 130 wrestlers. They found that most wrestlers were similar in height but had smaller upper body skin folds when compared to National Health and Nutrition Examination Survey (NHANES) samples and that wrestling had favorable effects on measures of adiposity.

The article discusses research which investigated the relationship between physical performance and match performance in Australian Rules Football. Researchers evaluated the performance of 36 semiprofessional players. They found that the three kilometer time trial performance was a predictor of direct game involvement per minute and that playing experience was related to match performance.

The article reports on research which compared linear and daily undulating periodized resistance training and their affects on anthropometrical, strength and judo specific performance. Researchers compared both training programs with 13 adult male judo athletes who underwent eight weeks of training. They found that both training programs led to decreases in skinfold thickness and increases in several other parameters, including flexed arm and forearm circumferences, maximal isometric handgrip strength and dynamic strength.

The article reports on research which was conducted to investigate the rating of perceived exertion values corresponding to blood lactate concentration training zone boundaries in runners using the Borg CR-10 scale. Researchers evaluated 95 runners. They found that the rate of perceived exertion could be rated using the scale and that rating perceived exertion could be used as a tool to control intensity and keep athletes in prescribed zones during training sessions.

The article discusses research comparing the acute effects of concurrent training (CT) on the hormonal responses in concurrently trained men randomly assigned to either an endurance training followed by strength (ES) group or a strength training followed by endurance (SE) group, using a pretest-posttest design. The effects of CT on serum concentrations of testosterone, cortisol, growth hormone, and IGF-1 binding protein 3 (IG FBP-3) are discussed.

The article discusses research comparing the acute metabolic responses to traditional resistance, body-weight, and battling rope (BR) exercises in 10 resistance-trained men. Topics include the participants' exercise protocol, which included repetitions of push-ups (PUs), PUs on a BOSU ball, and PUs with lateral crawls, measurements of mean oxygen consumption during PU-based and plank exercises, and acute energy expenditure (EE) in body fat reduction.

The article discusses research which was conducted to investigate the effect gender had on the growth hormone–insulin-like growth factor-I (GH-IGF-I) response to anaerobic exercise in young adults. Researchers evaluated 12 male and 16 female subjects who performed anaerobic exercise. They found that anaerobic exercise was associated with a greater and earlier postexercise GH peak in women than in men.

The article reports on research which was conducted to compare acute counter movement jump (CMJ) responses after functional isometric (FI) and dynamic half (DH) squats. Researchers evaluated 10 male subjects who performed either FI or DH squats. They found that because of a lack of CMJ responses the use of DH squats rather than FI squats should be considered for training and precompetition situations.

The article reports on research which was conducted to compare the energy expenditures and heart rates of subjects who participated in a live exercise session or one which featured a guided workout on DVD. Researchers evaluated the two types of exercise sessions with 20 female college students. They found that energy expenditure and heart rate were higher in subjects that participated in live exercise and that the majority of students indicated that they preferred live exercise sessions with a personal trainer over exercise sessions that featured the use of a DVD.

The article reports on research which was conducted to investigate the effects a 12 week strength training program had on fencers' movement times. Researchers evaluated the program with 12 experienced male fencers. They found that fencers who were involved in the strength training program had increases in strength and jumping ability and improvements in movement time.

The article reports on research which was conducted to evaluate changes in anthropometry and performance and their interrelationship during three seasons of play in elite youth rugby league players. Researchers evaluated 13 players. They found that over the course of three seasons there were increases in lean body mass in the players which helped them generate horizontal speed and vertical power.

The article discusses research which was conducted to investigate the seasonal changes in anthropometric and physical characteristics in English academy rugby league players according to their ages. Researchers evaluated 75 players under the ages of 14, 16, 18 and 20. They found that different age groups improved in different tests and body measurements and that older and younger players improved at different rates due to different age related body characteristics.

The article discusses research investigating sex-related differences in explosive actions during late childhood using to allometric analysis for body size and maturity. 68 boys and 45 girls approximately 11 years of age performed various actions, including vertical and horizontal jumps, a 30-meter (M) sprint, and a change-of-direction (COD) time trial. The authors' recommendation for a training emphasis on sprinting and COD at a younger age in girls compared with boys is discussed.

The article presents a study on the effect of acute fluid consumption on urine specific gravity (Usg), body mass, percent body fat (%BF), and minimum wrestling weight (MWW) following exercise-induced fluid loss in wrestlers. Topics include bioelectrical impedance,air displacement plethysmography (ADP), and weight certification program (WCP).

The article presents a study on the relationship between the stride angle and and running economy (RE) in well-trained long-distance runners. Topics include biomechanical variables of running, aerobic capacity, and running performance. Ground contact time, running speed, swing phase, and stride length are also discussed.

The article presents a study on the relationship between maximal oxygen consumption (Vo2max) and acute resistance exercise performance, as well as the maximal aerobic capacity and acute metabolic effects of exercise sequencing, with a focus on rest interval (RI) lengths. Resistance training, athletic performance, and strength testing are also discussed.

The article presents a study on the relationships between 30-meter sprint time and sprinting performance on a nonmotorized treadmill (TM) test and a jump test, with a focus on speed, force, and power values. Topics include peak power (PP), stepwise regression, and body composition. The Wingate anaerobic power test (WAnT) is also discussed.

The article reports on research which was conducted to investigate the effects an eight day interval training block had on aerobic capacity, performance and physiology in junior alpine skiers who performed the 90 second box test, a test designed to simulate alpine skiing. Researchers found that performance and aerobic energy contribution during the box test did not increase but that athletes did alter their pacing strategy.

The article reports on research which was conducted to investigate the effectiveness of Olympic style weightlifting (OWL), plyometric and traditional resistance training in children. Researchers evaluated 63 children who were assigned to one of the three training programs. They concluded that any of the three training methods could be implemented with children to enhance training adaptations.

The article reports on research which investigated the effects fatigue from resistance training had on barbell back squat biomechanics. Researchers evaluated 12 men and 13 women who performed several weight lifting tasks. They found that the technique changes that occur in high repetition sets do not favor optimal strength development and may increase the risk of injury and may also lead to questions about the safety and efficacy of such resistance training programming.

The article reports on research which was conducted to compare traditional periodized (TP) and block periodized (BP) strength training programs in trained athletes. Researchers evaluated the two programs with 24 resistance trained men. They found that BP may enhance upper-body power expression more than TP with equal volume and that no differences were detected for lower body performance and body composition measures.

The article reports on research which investigated the effect that mouth only breathing had on time to completion, heart rate, rate of perceived exertion, blood lactate, and ventilatory measures during a high-intensity shuttle run sequence. Researchers evaluated ten subjects. They found that the mouth breathing only impacted heart rate and that its use was questionable for training purposes.

The article presents research on sex-specific responses during self-paced, high-intensity interval training (HIIT), with a focus on variable recovery periods. Topics include the results of peak oxygen uptake tests during HIIT sessions, the length of recovery time between intervals, and a comparison of men and women's results for the rate of recovery during high-intensity exercise.

The article reports on research which was conducted to investigate thermoregulatory, cardiovascular and perceptual response to intermittent cooling during exercise in a hot, humid outdoor environment. Researchers evaluated intermittent cooling with 10 healthy male subjects. They found that intermittent cooling was effective in reducing skin temperature but did not sufficiently reduce core body temperature or cardiovascular strain.

The article presents research on the locomotive activities of and exercise intensity in eight female rugby union players during a game, noting that the players' activities such as standing and running as well as the total distance they covered were analyzed using a global positioning system. The study found that the backs position players covered more total distance than players in the forwards position. It also notes the percentage of match time that players were at their maximum heart rate.

Research is presented which compared the fluid and electrolyte balance of elite rugby players during two preseason training sessions that focused on resistance and aerobic exercise. The observational study found that 80 percent of the participants were in a hypohydrated state when they began training and that they did not match their fluid intake with their sweat loss. Underdrinking of fluids during aerobic training and overdrinking during resistance training are noted.

Research is presented which examined methods for quantifying training in Sprint Kayak and monitoring the fitness and performance of 10 junior Sprint Kayak athletes with a focus on the session rating of perceived exertion (session-RPE) method and common measures of training load (TL). The study found that session-RPE is a valid method for monitoring TL for junior Sprint Kayak athletes and also supports the use of session-RPE in Sprint Kayak training.

Research is presented that examined the effects of a 21-week competitive season on 34 child soccer players' salivary immunoglobulin A (SIgA) response and upper respiratory tract infection (URTI) symptoms. The study found that the demands of training and competition affected the children's mucosal immune responses.

Research is presented that focuses on the effect of strength and high-intensity training on child soccer players' sprinting, jumping, and intermittent endurance performance. The 24 participants were randomly assigned to a control (C) group or the S group which performed combined strength and high-intensity training before starting the identical soccer-training program used by the C group. Improvements in flexibility and countermovement jumps were found in the S group.

The article presents research that assessed the anthropometric and physical characteristics of English rugby league players and compared those in the under 16s and under 20s age groups as well as those of players in the backs and forwards rugby positions. The study found that these characteristics develop across the age categories and between the backs and forwards categories.

The article discusses a study of the attributes of top team-handball players which indicates that a fitness model which considers body mass, sprint time, offensive power, ego-based motivational orientation, and the energy spent in handball activity can frequently predict the probability of an athlete becoming an elite team-handball player. Logistic regression analysis is mentioned.

The article focuses on an examination of the physical profiles of football team players for the 2011 New York Giants and compare them with previous National Football League (NFL) player profiles. It states that skinfold measurements were used to collect height, body mass, and body fat percentage. It mentions that anthropometrics profiles didn't differ significantly from previous trends in NFL players.

The article focuses on a study which was conducted to determine which method of concurrent strength-endurance training would be most useful for improving running performance in trained runners. It was found that adding explosive and strength-endurance training to the normal training of the runners resulted in improvement in running performance.