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As technology within elite basketball advances and is more available to sporting organizations, novel approaches for assessing and addressing athletic performance during practice or competition are being continuously explored. The aim of this investigation was to examine changes in neuromuscular performance during live basketball play. Eight professional male basketball players volunteered to participate in this study. The testing procedures were conducted during a pre-tournament camp over a span of 2 days. During the first day, the athletes were familiarized with the testing procedures, and baseline measurements were obtained. Using a uniaxial force plate system sampling at 1,000 Hz, each athlete performed 3 countermovement vertical jumps (CVJ) without an arm swing before proceeding with their regular training activities. During the second day of the pre-tournament camp, the athletes repeated identical CVJ testing procedures before the start of the first quarter and post-first, second, third, and fourth quarter of a simulated 5- on-5 basketball game. Repeated-measures testing design was used to examine statistically significant differences in various forcetime metrics of interest in comparison to the baseline levels (p, 0.05). Besides a trivial decrease in eccentric mean force, the findings of this study revealed no statistically significant changes in any force-time metrics of interest within both eccentric and concentric phases of the CVJ (i.e., mean and peak force and power, jump height, impulse, velocity, and contraction time). Thus, we can conclude that these variables were not sensitive to acute fatigue, suggesting that the neuromuscular performances of professional male basketball players tend to remain unchanged throughout a 5-on-5 simulated game. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the relationship between external workload exposure and changes in countermovement jump force-time characteristics over the course of an entire basketball season, in a sample of National Collegiate Athletic Association Division I, female, basketball players. Data for 12 players were retrospectively analyzed, with external workload being quantified by means of an exponentially weighted, acute, and chronic workload, as well as an acute:chronic workload ratio derived from an inertial measurement unit--based system worn by athletes for all practices and games during the regular season. Countermovement jumps were performed on a total of 26 test days over the span of the in-season competitive period. To statistically analyze these relationships, and to account for multiple observations of the same athletes in a data set, linear mixed-effects models with athlete identity (ID) intercept as the random effect were used. Study findings suggested that associations between external workload exposure and respective force-time characteristics after controlling for the random effect of athlete ID were dependent on the specific metric or metric subgroup used, as well as the type of workload exposure (e.g., acute vs. chronic). Force-time signatures from the braking phase (e.g., average braking force) seemed to be particularly associated with higher degrees of acute workload exposure, whereas strategy-based metrics such as countermovement depth showed significant associations with chronic workload exposure. Furthermore, model results suggested the importance of analyzing neuromuscular responses to external workload on an individual basis, rather than across an entire team. Findings might help practitioners in their selection process related to metrics of interest in monitoring neuromuscular fatigue and readiness. [ABSTRACT FROM AUTHOR]

Cabarkapa, DV, Cabarkapa, D, Philipp, NM, and Fry, AC. Competitive season-long changes in countermovement vertical jump force-time metrics in female volleyball players. J Strength Cond Res 38(2): e72-e77, 2024--Although force plates remain one of the most widely used tools for neuromuscular performance assessment in applied sports-specific settings, there is still a lack of scientific literature focused on studying changes in countermovement vertical jump (CVJ) performance in team sports such as volleyball, especially within the female athlete population. Thus, the purpose of the present study was to examine season-long neuromuscular performance changes in volleyball players. Eighteen National Association of Intercollegiate Athletics Division-I collegiate female athletes performed 3 maximal-effort CVJs while standing on a uniaxial force plate system sampling at 1,000 Hz at 5 different testing timepoints throughout a competitive season span (;11 weeks). The testing sessions were separated 2-3 weeks apart and performed at the approximately same time of the day (12:00 hours). Repeated-measures analysis of variance revealed that both concentric and eccentric force-time metrics remain relatively unchanged throughout a regular season span (e.g., concentric peak force and power, eccentric impulse and duration). However, the eccentric metrics such as peak and mean power and peak velocity displayed a slight improvement after a brief tapering period purposely implemented before the post-season competition to optimize the athlete's recovery (;15, 18, and 14% increase, respectively). In addition, the outcome metrics such as vertical jump height and reactive strength index-modified did not display notable fluctuations across the competitive season span. These findings can help coaches, sports scientists, and strength and conditioning practitioners to obtain a deeper insight into collegiate female athletes' force-time characteristics that may aid with developing adequate training regimens targeted toward optimizing on-court performance. [ABSTRACT FROM AUTHOR]

Lower-body strength and power are commonly measured performance qualities across a number of sports. In recent years, more attention has been given to relationships, primarily between lower-body strength and linear speed performance. While still limited, evidence is in agreement that lower-body strength positively contributes to linear speed performance. However, what is less well understood is if there comes a point in an athlete's development, at which, further working on increasing maximal strength may not fully compliment additional gains in speed performance. Within this study, authors aimed to provide practitioners with lower-body strength and power thresholds that can discriminate between slow and fast performers, within a group of collegiate American football players. The sample was further divided into a high-body and low-body weight group, and authors hypothesized that by using logistic regression, supplemented with receiver operator curve analyses, optimal cut-off points (i.e., relative lower-body strength thresholds) that are able to significantly discriminate between slow and fast linear speed performers may be identified. Findings indicate that optimal cut-off scores differed between the groups of athletes, as well as the lower body strength and power tests. All models were able to significantly distinguish between slower and faster performers, and area under the curve values ranged from 0.695 to 0.903. Although thresholds will likely vary based on factors such as sex, training age, and sport, findings from this investigation may be used to benchmark athletes and to further individualize training aimed at improving linear speed performance. [ABSTRACT FROM AUTHOR]

Cabarkapa, D, Cabarkapa, DV, Philipp, NM, Knezevic, OM, Mirkov, DM, and Fry, AC. Pre-post practice changes in countermovement vertical jump force-time metrics in professional male basketball players. J Strength Cond Res 37(11): e609-e612, 2023--Despite the countermovement vertical jump (CVJ) being one of the most popular noninvasive and time-efficient methods for monitoring neuromuscular status, there is a lack of scientific literature focused on examining fatigue-induced alterations in performance in elite athletes. Thus, the purpose of this study was to examine changes in force-time metrics pre-post practice in professional male basketball players. Seventeen athletes competing in first-tier and second-tier national basketball leagues in Europe participated in this study. While standing on a uniaxial force plate sampling at 1,000 Hz, each athlete completed 3 CVJs pre-practice and post-practice. The practice consisted of individual and team shooting drills, position-specific player development drills, 5-on-0 offensive actions, and 5-on-5 play, including full-court transition (;2 hours). The findings reveal that pre-post practice changes in force-time metrics seemto be phase specific. Despite a trivial increase in eccentric mean force (920.4 6 100.2, 929.4 6 100.0 N), most changes were observed within the concentric phase of the CVJ. The concentric phase duration increased pre-post practice (0.233 6 0.027, 0.242 6 0.033 seconds), whereas concentric impulse (262.9618.8, 258.6621.6 N·s), peak velocity (2.9360.22, 2.8660.22m·s21), mean force (2052.46179.2, 2002.76188.2 N), mean power (3,165.56269.5, 3,030.96326.8W), and peak power (5,523.46607.3, 5,246.6 6663.7W) experienced a significant decrease. Moreover, alongside longer contraction time(0.66360.065, 0.68660.074 seconds), lower vertical jump height (41.0 6 6.8, 38.9 6 6.6 cm) and reactive strength index-modified (0.634 6 0.113, 0.579 6 0.111 m·s21) values were observed post-practice. Overall, these findings may allow practitioners to detect fatigue-induced changes in CVJ forcetime metrics in professional male basketball players that can ultimately improve the acute and longitudinal training-adaptation monitoring process. [ABSTRACT FROM AUTHOR]

Postactivation performance enhancement has been reported for multijoint resistance exercise, with both neural and intrinsic muscle mechanisms suggested as contributing factors. The purpose of this investigation was to examine whether regulatory light-chain (RLC) phosphorylation in a primary mover is associated with enhanced weightlifting performance. Nine male athletes performed 15 sets of 3 repetitions of a multijoint weightlifting activity (clean pull) at 85% 1 repetition maximum. Measures of performance, peak barbell velocity (PV), and average barbell power (AP) were determined by video analysis. Muscle biopsies were taken within 30-60 seconds of completion of the previous lifting set from the vastus lateralis before (PRE), during (MID), and after (POST) a training session. AP was significantly greater for sets 3, 4, and 5 compared with set 1, with large effect sizes (0.8-1.0). Increases in PV did not reach significance; however, the effect size increase for sets 3 and 4 versus set 1 was moderate (0.4). Relative change scores for AP and RLC phosphorylation were positively and negatively correlated at MID (r = 0.60; p = 0.05) and POST (r = -0.74; p = -0.01) exercise, respectively. These data suggest that RLC phosphorylation initially may be associated with postactivation performance enhancement during repeated multijoint exercise. [ABSTRACT FROM AUTHOR]

Intentionally slow-velocity resistance exercise (ISVRE) is suggested by some to be equally or more effective than fast or traditional velocities for increasing muscular strength. The purpose of this meta-analysis was to assess the effect ISVRE has on strength adaptations compared with faster or traditional velocities, with subgroup analyses exploring age, sex, and training status as confounding factors on the influence of velocity on strength adaptation. Eligible studies (n 5 24) were required to be chronic (multiple weeks) randomized or nonrandomized comparative studies using dynamic constant external resistance for training and testing, and pre-post strength assessments. All studies examined healthy individuals (n = 625; fast or traditional n = 306, intentionally slow n = 319). A random-effects meta-analysis indicated a significant (p ≤ 0.05) effect in favor of fast training (effect size [ES] = 0.21, 95% confidence interval [CI] = 0.02-0.41, p = 0.03). Publication bias was noted through trim and fill analysis, with an adjusted effect size estimate of 0.32 (p < 0.001). Subgroup analyses indicated no difference between trained and untrained subjects (QM = 0.01, p = 0.93), and no difference between older and younger subgroups (QM = 0.09, p = 0.77), despite younger favoring faster (ES = 0.23, p = 0.049) and older not favoring either velocity (ES = 0.16, p = 0.46). Subgroup analysis also indicated women favored faster training (ES = 0.95, p < 0.001) in comparison to men (ES = 0.08, p = 0.58). Contrary to some previous reviews, these results indicate that chronic fast or traditional velocity resistance exercise increases muscular strength to a greater degree than ISVRE training. Resistance training velocity must be considered if strength is a desired outcome. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine acute changes in salivary testosterone (T), cortisol (C), and testosterone-to-cortisol ratio (T/C) during a simulated 5-on-5 basketball game. Seven professional male basketball players volunteered to participate in this study. Repeated-measures analysis design was used to examine changes in hormonal concentrations across 8 testing time points: immediately upon arrival to the gymnasium- baseline (BS); post-warm-up (PW); post-first (P1Q), second (P2Q), third (P3Q), and fourth quarter (P4Q); and 30 (P30) and 60 minutes (P60) postgame. The findings of this study indicate that a simulated 5-on-5 basketball game provoked significant changes in salivary T, C, and T/C. When compared to the BS levels (... ± SD [nmol⋅L-1]; 6.72 ± 2.53), salivary C concentration experienced a notable increase P3Q (16.20 ± 7.70) and remained elevated throughout the rest of the sampling periods, with values failing to return to BS levels P60 (11.88 ± 5.58). Conversely, a significant increase in salivary T occurred P1Q (0.76 ± 0.21) when compared to the BS levels (0.58 ± 0.12) and remained elevated up to P30 (0.75 ± 0.20), with values returning to BS levels P60 (0.63 ± 0.14). In addition, despite no significant intragame alterations, T/C exhibited a notable decrease P30 (0.06 ± 0.02) and P60 (0.07 ± 0.04), when compared to BS values (0.10 ± 0.04). Overall, these findings provide additional insight into the physiological stress that basketball players are exposed to during 5-on-5 competitive play and can be used to appropriately adjust and monitor training loads to optimize recovery and on-court basketball performance. [ABSTRACT FROM AUTHOR]

The origins of weightlifting and feats of strength span back to ancient Egypt, China, and Greece, with the introduction of weightlifting into the Olympic Games in 1896. However, it was not until the 1950s that training based on weightlifting was adopted by strength coaches working with team sports and athletics, with weightlifting research in peerreviewed journals becoming prominent since the 1970s. Over the past few decades, researchers have focused on the use of weightlifting-based training to enhance performance in nonweightlifters because of the biomechanical similarities (e.g., rapid forceful extension of the hips, knees, and ankles) associated with the second pull phase of the clean and snatch, the drive/thrust phase of the jerk and athletic tasks such as jumping and sprinting. The highest force, rate of force development, and power outputs have been reported during such movements, highlighting the potential for such tasks to enhance these key physical qualities in athletes. In addition, the ability to manipulate barbell load across the extensive range of weightlifting exercises and their derivatives permits the strength and conditioning coach the opportunity to emphasize the development of strength-speed and speed-strength, as required for the individual athlete. As such, the results of numerous longitudinal studies and subsequent meta-analyses demonstrate the inclusion of weightlifting exercises into strength and conditioning programs results in greater improvements in force-production characteristics and performance in athletic tasks than general resistance training or plyometric training alone. However, it is essential that such exercises are appropriately programmed adopting a sequential approach across training blocks (including exercise variation, loads, and volumes) to ensure the desired adaptations, whereas strength and conditioning coaches emphasize appropriate technique and skill development of athletes performing such exercises. [ABSTRACT FROM AUTHOR]

Sontag, SA, Cabarkapa, D, and Fry, AC. Testosterone and cortisol salivary samples are stable across multiple freeze-thaw cycles. J Strength Cond Res 37(4): 915–918, 2023—When processing salivary samples for biomarker analysis, avoiding multiple freeze-thaw cycles is generally recommended. However, confusing tissue handling instructions or challenges with collections in the field sometimes makes this problematic. Thus, the purpose of this study was to examine if the stability of salivary testosterone (T) and cortisol (C) hormones remains unchanged when exposed to multiple freeze-thaw cycles. Seven healthy recreationally active adults provided salivary samples at rest (i.e., 1600 hours) for analysis of T and C. Samples were separated into 4 aliquots for each hormone and underwent 4 freeze-thaw cycles (T1–T4 and C1–C4) before being analyzed by enzyme-linked immunosorbent assay. The overall analysis of variance model was significant for T (p = 0.008) and nonsignificant for C (p = 0.820). A follow-up post hoc comparison indicated significant differences in salivary hormonal concentrations between T1 and T4 (p = 0.029), T2 and T4 (p = 0.007), and T3 and T4 (p = 0.032). The findings of this study indicate that salivary steroid hormones seem to be relatively stable following multiple freeze-thaw cycles. However, C seems to be more stable when exposed to multiple freeze-thaw cycles, as T concentrations did reveal a significant decrease by the fourth thaw cycle. [ABSTRACT FROM AUTHOR]

Periodization can be defined as a logical sequential, phasic method of manipulating fitness and recovery phases to increase the potential for achieving specific performance goals while minimizing the potential for nonfunctional overreaching, overtraining, and injury. Periodization deals with the micromanagement of timelines and fitness phases and is cyclic in nature. On the other hand, programming deals with the micromanagement of the training process and deals with exercise selection, volume, intensity, etc. Evidence indicates that a periodized training process coupled with appropriate programming can produce superior athletic enhancement compared with nonperiodized process. There are 2 models of periodization, traditional and block. Traditional can take different forms (i.e., reverse). Block periodization has 2 subtypes, single goal or factor (individual sports) and multiple goals or factors (team sports). Both models have strengths and weaknesses but can be "tailored" through creative programming to produce excellent results for specific sports. [ABSTRACT FROM AUTHOR]

Fry, AC, Parra, ME, and Cabarkapa, D. Supplemental creatine modified with polyethylene glycol effectively loads skeletal muscle with lower doses. J Strength Cond Res 35(5): 1256-1261, 2021--The purpose of this study was to compare the efficacy of skeletal muscle uptake of creatine monohydrate (Cr H2O) with that of creatine bound to polyethylene glycol (Cr PEG). Healthy men (X6 SE; age = 23.5 6 1.0 years) were divided into control (Con, n = 9, 20 g·d-1 of Cr H2O) and experimental (Exp, n = 8, 10 g·d-1 of Cr PEG) groups. Blood samples and muscle biopsies were used to determine acute gastrointestinal absorption over = hours and muscle cellular uptake over = days. Both groups exhibited significantly (p, 0.05) elevated concentrations of muscle-free Cr (M·gdw -1; Con, pre=23.064.2, post=39.262.7; Exp pre=22.162.9, post=33.663.2), total Cr (M·gdw -1, Con pre=94.7 6 =.4, post = 114.8 ± 7.4; Exp pre = 92.6 ± 5.4, post = 106.6 ± 8.4), which were also elevated when these values were normalized for adenosine triphosphate using molar ratios. Circulatory uptake of Cr was significantly different between the groups, with blood concentrations (mg·dL-1) for the Con group peaking at 2 hours post-ingestion (25.99 ± 2.96), whereas the concentrations for the Exp group were lower and were still rising at = hours (4.0560.87). The integrated area under the curve for the 5-hour postingestion period was 7-fold greater for the Con group. Although total Cr ingested over the = days supplementation period was less for the Cr PEG group, skeletal muscle uptake of Cr PEG was similar to CrH2O. Based on circulating Cr concentrations, it seems that Cr PEG is cleared more slowly from the gastrointestinal tract. Thus, lower dosages of Cr may be ingested while maintaining optimal loading kinetics. [ABSTRACT FROM AUTHOR]

Ciccone, AB, Fry, AC, Emerson, DM, Gallagher, PM, Herda, TJ, and Weir, JP. Effects of transspinal direct current stimulation on cycling perception of effort and time to exhaustion. J Strength Cond Res 35(2): 347-352, 2021-In the past decade, researchers have investigated the efficacy of transspinal direct current stimulation (tsDCS) on the central nervous system and afferent neuron function in humans. Recently, data have suggested it may be possible for such tsDCS-induced changes in neuromuscular function to enhance performance. This study used noninvasive thoracic spine tsDCS to determine if cycling performance and perception of effort could be modulated by tsDCS. In 3 different stimulation conditions, anodal, cathodal, and sham, subjects cycled at 80% of their maximal aerobic capacity until exhaustion and reported their rating of perceived exertion (RPE) every minute. From this period, we compared the RPE responses over the first 3 minutes and time to exhaustion. There was no significant difference in time to exhaustion between anodal (408 ± 121 seconds), cathodal (413 ± 168 seconds), and sham (440 ± 189 seconds) conditions (p = 0.58). There was no significant difference in RPE from minutes 1-3 (collapsed across time) between anodal (12.9 ± 2.4 arbitrary units (AUs)), cathodal (13.3 ± 2.2 AUs), and sham (12.9 ± 2.1 AUs) conditions (p = 0.51). These data suggest tsDCS condition did not influence cycling performance or perception of effort during high-intensity cycling. Therefore, thoracic spine and lower abdominal montage delivering a current density of 0.071 mA·cm-2 for 20 minutes likely does not substantially improve high-intensity cycling work capacity. Therefore, more research is needed to investigate the efficacy of tsDCS and which stimulation methods may and may not enhance human performance. [ABSTRACT FROM AUTHOR]

This study examined the kinetic contributions of the upper extremities during countermovement vertical jumps (CMVJs) while using arm swing (AS) or no arm swing (NAS) conditions. Fourteen healthy men (... ± SD; age = 24.1 ± 3.9 years) volunteered for this investigation. Subjects performed in random order a total of 6 jumps consisting of 3 AS and 3 NAS CMVJs. A motion capture system was used to analyze the kinetic data. Paired samples t-tests were used to examine the subjects' mean differences in the AS and NAS CMVJ trials (p<0.05). Results for all subjects were determined for each jump subjects were determined for each jump performed, with statistical analyses performed on mean values for all 3 jumps per subject. The AS significantly increased the vertical jump height (VJH) by an average of 0.07 ± 0.03 m (3.0 ± 1.3 inches). Dual-energy X-ray absorptiometry scans determined that the upper limbs were 12.0% of the total body mass. Movement of the upper limbs during the AS CMVJ produced 32.2 ± 7.0% of the total mean ground reaction force (GRF), and 11.3 ± 2.2% during the NAS CMVJ. The enhancement of performance when jumping using an AS resulted in a 13.6% increase in VJH. The contribution of the upper limbs during the AS CMVJ averaged 31.5% of the peak GRF, which occurred immediately before takeoff. The upper extremities can greatly influence vertical jump performances and the accompanying kinetics. When analyzing jump GRFs, one must be aware of how much the upper limbs contribute to these forces. In addition, proper AS mechanics must be emphasized when instructing correct jump technique. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the effect of 3 different back squat protocols on intracellular signaling, endocrine responses, and power fatigue. Nine recreationally trained men (X ± SD; age: 21.4 ± 0.6 years; height: 177.8 ± 5.1 cm; body mass: 78.7 ± 9.7 kg), completed 3 maximal concentric velocity squat protocols in a randomized order. Testing protocols consisted of 5 sets of 10 repetitions at 30% of 1 repetition maximum (1RM); 5 sets of 5 repetitions at 70% of 1RM; and 5 sets of 3 repetitions at 90% of 1RM. Average system power for each set was obtained using a tethered external dynamometer. Pre-exercise and postexercise blood draws were analyzed for lactate, testosterone, human growth hormone (hGH), and cortisol. Muscle biopsies assessed pre-exercise and postexercise extracellular signal-regulated kinase 1/2 (ERK1/2) and p38 phosphorylation using western blotting. Cortisol, hGH, and lactate increased after exercise (p ≤ 0.05), but did not differ between protocols (p > 0.05). Testosterone was unaltered (p > 0.05). Average power was lower for the 90% protocol than for the 30% protocol across all sets (p < 0.01). Average power was lower after the fourth and fifth set compared with the first and second set in the 90% protocol only (p ≤ 0.05). The ratio of phosphorylated-to-total ERK1/2 was higher postexercise after 90% protocol only (p ≤ 0.05). The ratio of phosphorylated-to-total p38 was unaltered after exercise (p > 0.05). Resistance load seems to affect power fatigue across the 5 sets of resistance exercise. This study found modest changes in ERK1/2 and no changes in p38 phosphorylation after maximal concentric velocity squats. Exercise volume, modality, and training status of subjects may account for these findings. [ABSTRACT FROM AUTHOR]

The purpose of this study was compare the effect of internal and external focus of attention instructions on force-time characteristics of the countermovement jump (CMJ) in collegiate student-athletes. Forty-three resistance-trained men (... ± SD; age = 20 ± 1.5 years) on an NCAA Division I baseball team volunteered to participate in this study. Each participant performed a total of 16 CMJs on a force platform while holding a wooden dowel on their shoulders to eliminate arm swing. Force and power parameters such as jump height (JH), peak velocity (PV), and mean concentric velocity (MCV) were calculated from force-time and position data. Paired-sample t-tests and Cohen's d effect sizes were used to examine differences between conditions. When subjects were instructed using an external focus, they demonstrated significantly (p < 0.05) greater JH, PV, and MCV compared with jumps performed with the internal focus (external JH = 48.0 ± 5.6 cm, internal JH = 46.4 ± 5.4 cm; external PV = 3.6 ± 0.3 m⋅s-1, internal PV = 3.5 ± 0.3 m⋅s-1; and external MCV = 2.31 ± 0.22 m⋅s-1, internal MCV = 2.25 ± 0.23 m⋅s-1). It is interesting to note that there was superior recall of the internal instructions during the manipulation checks that may suggest that the subjects consciously processed these instructions to a greater extent and reduced internal condition performance. These results indicate that instructions can alter the efficiency and performance of a skill. According to the literature and this study, if an optimum performance metric is desired, external focus of attention instructions should be used. [ABSTRACT FROM AUTHOR]

Numerous conditions and types of physical activity (e.g., exercise, aging, muscle-related diseases) can influence muscle fiber types and the proteins expressed. To date, muscle fibers can only be characterized by actually obtaining a tissue sample using the invasive muscle biopsy procedure. Mechanomyography (MMG) is the assessment of the vibration properties of contracting skeletal muscle, and has been proposed as a possible non-invasive method for muscle fiber analysis. Therefore, the purpose of this project was to examine the feasibility of using MMG and muscle performance measures to non-invasively assess muscle fiber characteristics. Fifteen men (5 endurance-trained [End], 5 weight-trained [WT], and 5 sedentary [Sed]) provided muscle samples from their vastus lateralis muscle. These samples were analyzed for relative myosin heavy chain protein expression, which is highly correlated with % muscle fiber type areas. Additionally, each subject performed several muscle performance tests, and MMG of the quadriceps was assessed during a knee extension exercise. Multiple regression was used to develop prediction equations for determining relative muscle content of myosin heavy chain (MHC) types I, IIa, and IIx. A combination of MMG and knee extension performance variables estimated types I, IIa, and IIx MHC with approximately 80% accuracy. Although preliminary, these data suggest that muscle performance tests in addition to MMG assessments during a simple muscle performance task (knee extension) can be used to estimate muscle fiber type composition in a healthy male population. Such methods could ultimately be used to non-invasively monitor muscle health and fitness. [ABSTRACT FROM AUTHOR]

Luebbers, PE and Fry, AC. The Kansas squat test: A valid and practical measure of anaerobic power for track and field power athletes. J Strength Cond Res 29(10): 2716-2722, 2015— The Kansas squat test (KST) is a repetitive lifting test designed to measure relatively similar indices of lower-body power as the Wingate anaerobic test (WAnT). The purposes of this study were twofold: determine concurrent validity of the KST using the WAnT as the criterion measure and also demonstrate the KST as a practical test of anaerobic power for track and field athletes. Twenty-three track and field athletes participated (mean 6 SD; 77.2 6 16.8 kg, 175.6 6 8.7 cm). Each completed the KST, and on a separate occasion, the WAnT for comparison. Correlation coefficients indicated significant relationships between the KST and the WAnT on measures of maximum test power (r = 0.920, p , 0.01) and mean test power (r = 0.929, p , 0.01), but not for relative fatigue (r = 0.030, p . 0.05). The posttest lactate response also lacked a significant relationship (r = 20.062, p . 0.05). These relationships were also present when athletes were examined in subgroups based on gender and event. Paired-samples t-tests indicated that while peak power and mean power were significantly higher for the KST (p # 0.01), relative fatigue and lactate were both significantly higher for the WAnT (p # 0.01). These significant differences were similar in the subsequent subgroupings of the athletes. These data support that the KST is a concurrently valid assessment of lower-body anaerobic power. This study further illustrates a practical lower-body power testing method that is lift specific, which may aid in improving training specificity for track and field power athletes. [ABSTRACT FROM AUTHOR]

The article presents a study to determine the accuracy in position of a Vertical Jump (VJ) mat for calculating flight time and height in comparison with a force plate and Vertec VJ Tester. 17 men and 18 women performed counter movement vertical jumps from a force plate and a VJ mat and the height was calculated using Vertec VJ tester. No remarkable difference was seen in values of VJ heights calculated, but regression analysis suggests inaccuracy calculating high VJ performances using VJ mat.

The article reports on research conducted to investigate the effect a seven week blood flow restriction (BFR) protocol used along with a strength training program had on muscle strength and size in U.S. college football players. Researchers evaluated upper and lower girth and performance in the squat exercise and bench press in players who participated in both programs. They found that both programs affected each of those variables and that the BFR especially improved squat performance.

The article reports on research which was conducted to establish stability reliability of a measure of lower-body anaerobic power, the Kansas squat test (KST), and to compare the KST with the Wingate anaerobic test (WAnT) for lower-body power. Researchers evaluated both tests with 14 resistance trained men. They found that the KST is reliable for resistance-trained men, and that measures of maximum and mean test powers for the KST are highly correlated to those values for the WAnT, but that fatigue rates and lactate responses were not correlated.

The article discusses research which was conducted to develop a reliable method for determining friction and pulling forces during a weighted sled pull conducted with different loads. After developing and testing the method researchers concluded that it was effective in determining friction and pulling forces.

The article presents the results of a study which investigated the neuroendocrine responses in wrestlers which correlated with success or failure in competitive wrestling matches. An overview of related previous research is provided, along with details of the experimental protocol, which involved analysis of testosterone and cortisol levels in serum samples.

The article reports on research conducted to investigate the influence of four methods of standing reach height measurement and Vertec jump height measurement against 2 force plate methods of jump displacement determination in athletes while evaluating impulse and flight-time methods. Researchers evaluated 15 athletes. They found that one hand reach with plantar flexion was the method of reach closest to the impulse and flight-time methods and should be used to determine jump displacement.

The article reports on research conducted to determine if the combination of isometric knee extension strength and mechanomyographic median frequency could be used to estimate the percent of myosin heavy chain (MHC) type two isoform content of the vastus lateralis. Researchers evaluated five resistance trained men and five aerobically trained men. They found that the combination could be used to estimate isoform content in well-trained men.

The article presents the results of a study which compared the effect of training muscular strength and force production with barbells or with a weight training machine. The exercise tested was the power clean. Details of the experimental protocol are provided. It was found that barbells produced superior results.

The article discusses a study to examine the influence of myosin heavy chain (MHC) isoform composition and training status on the mechanomyographic (MMG) amplitude versus isometric torque relationship for the vastus lateralis. There were no consistent patterns of responses for the resistance-trained, aerobically trained or sedentary subjects for MMG amplitude versus torque. The differences in MHC isoform composition and training status did not explain the torque-related patterns.

Court sports often require more frequent changes of direction (COD) than field sports. Most court sports require 180= turns over a small distance, so COD in such sports might be best evaluated with an agility test involving short sprints and sharp turns. The purposes of this study were to (a) quantify vertical and horizontal force during a COD task, (b) identify possible predictors of court-sport-specific agility performance, and (c) examine performance difference between National Collegiate Athletic Association Division I, II, and III athletes. Twenty-nine collegiate female volleyball players completed a novel agility test, countermovement (CM) and drop jump tests, and an isometric leg extensor test. The number of athletes by division was as follows: I (n = 9), II (n = 11), and III (n = 9). The agility test consisted of 4 5-meter sprints with 3 180= turns, including 1 on a multiaxial force platform so that the kinetic properties of the COD could be identified. One-way analysis of variance revealed that Division I athletes had significantly greater countermovement jump heights than Division III, and the effect size comparisons (Cohen's d) showed large-magnitude differences between Division I and both Divisions II and III for jump height. No other differences in performance variables were noted between divisions, although effect sizes reached moderate values for some comparisons. Regression analysis revealed that CM displacement was a significant predictor of agility performance, explaining approximately 34% of the variance. Vertical force was found to account for much of the total force exerted during the contact phase of the COD task, suggesting that performance in the vertical domain may limit the COD task used herein. This study indicates that individuals with greater CM performance also have quicker agility times and suggests that training predominantly in the vertical domain may also yield improvements in certain types of agility performance. This may hold true even if such agility performance requires a horizontal component. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the performance and hormonal responses to a 15-week off-season training program for American football. Nine skill position players from a National Collegiate Athletic Association (NCAA) Division I-A football team participated as subjects in this study. Following 4 weeks of weight training (phase I), subjects performed weight training concurrently with high-volume conditioning drills (phase II). Phase III consisted of 15 spring football practice sessions executed over a 30-day period. Performance and hormonal changes were assessed prior to phase I, and following phases I, II, and III. Maximal strength was significantly increased (p > 0.05) for all strength tests during phase I. Squat and power clean values decreased following phase II (p > 0.05), with all values returning to baseline upon completion of phase III. Sprinting speed significantly worsened during phase I (p > 0.05), but then returned to baseline during phase III. Vertical jump and agility improved during phase I (p > 0.05), with vertical jump remaining unchanged for the duration of the study and agility returning to baseline following phase II. Testosterone levels decreased during phase II (p > 0.05) prior to returning to baseline levels during phase III. Cortisol and the testosterone/cortisol ratio remained unchanged during the course of the investigation. Even though overtraining did not occur in the current investigation, a significant maladaptation in performance did occur subsequent to phase II. For this particular athletic population, a strength and conditioning program utilizing a reduced training volume-load may prove more effective for improving performance in the future. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare the cortisol responses from a regular season game and a typical practice session in female National Collegiate Athletic Association Division I collegiate soccer players. Eighteen players were assigned to 2 groups, 10 starters and 8 nonstarters, depending on their playing time. Salivary cortisol concentration, as well as competitive sport anxiety (somatic and cognitive anxiety, self-confidence), was monitored before and after 1 regular season game and 1 typical practice session. Although salivary cortisol levels increased postgame for both starters (+250%) and nonstarters (+140%), they increased to a greater extent for the starters. Practice salivary cortisol did not significantly change (p > 0.05). Cognitive and somatic anxiety was greater pre-and postgame when compared with the pre-and postpractice scores, respectively. These data clearly demonstrate the psychological and physiological differences between soccer competition and practice in collegiate women. It appears that both physiological and psychological variables combine to contribute to the large stress hormone response to an actual competitive game. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the acute effects of a spectrum of eccentric loads on force, velocity, and power during the concentric portion of maximal-effort jump squats utilizing a repeated measures design. Thirteen resistance-trained men (age = 22.8 ± 2.9 years, weight = 87.1 ± 11.8 kg, 163.5 ± 28.6 kg squat 1 repetition maximum [1RM]; mean ± SD), who routinely incorporated back squats into their training, participated as subjects in this investigation. Jump squat performance was assessed using 4 experimental conditions. The first of these conditions consisted of an isoinertial load equal to 30% of back squat 1RM. The remaining conditions consisted of jump squats with a concentric load of 30% 1RM, subsequent to the application of experimental augmented eccentric loading (AEL) conditions of 20, 50, and 80% of back squat 1RM, respectively. All subjects performed 2 sets of 1RM of maximum- effort jump squats with all experimental conditions in a counter- balanced sequence. Forty-eight hours after completing the first testing session, subjects repeated the experimental testing protocol to establish stability reliability. Peak performance values for the reliable variables of force, velocity, and power, as well as force and power values obtained at 20-ms intervals during the initial 400 ms of the concentric jump squat range of motion, showed no statistical difference (p > 0.05) across the experimental AEL loads. These results suggest that load-spectrum AEL prior to a 30% 1RM jump squat fails to acutely enhance force, velocity, and power. [ABSTRACT FROM AUTHOR]

The purpose of this investigation was to evaluate the role of an elevated regulatory myosin light-chain (RLC) phosphorylation on subsequent postactivation potentiation induced by a 10-second maximum voluntary contraction (MVC). With the use of a repeated measures design, data were collected from 11 recreationally active men who performed an explosive knee extension exercise with a load of 70% of their 1 repetition maximum. Muscle biopsies of their vastus lateralis were taken pre- and post-MVC. Seven subjects had elevated RLC phosphorylation (positive responders) and 4 had a decrease in RLC phosphorylation (negative responders). Percent change of force, velocity, and power measures did not differ between the 2 groups. Our results suggest that recreationally active men will not benefit from the effects of postactivation potentiation during performance with a 7-minute recovery period. Furthermore, we suggest that training status, strength, and skill level might be key determining factors for the positive benefits of postactivation potentiation during performance. [ABSTRACT FROM AUTHOR]

The purpose of this study is to identify physical and performance variables that discriminate elite American junior-aged men weightlifters from nonelite performers. Using a cross-sectional design, multiple discriminant analysis was used to determine field tests identifying elite male junior weightlifters. Young men who were participants (n = 115) at the Junior National and Junior Olympics Weightlifting Championships volunteered as subjects (mean ± SD age = 14.8 ± 2.3 years). Elite weightlifters (n = 20) were identified as the top 17.5% of national-level competitors when weightlifting performances were adjusted for body mass using the Sinclair equation. All other weightlifters were classified as nonelite (n = 95). Test batteries were performed immediately upon completion of a national-level weightlifting competition. Variables measured included easily-administered field tests of physical dimensions and body composition, muscular strength and power, flexibility, and gross motor control. The resulting regression equations correctly classified 84.35% of the weightlifters as elite or nonelite. Five variables significantly contributed to the discriminant analysis (Wilks Λ= 0.6637392, χ2= 44.880, df = 5, p < 0.0001, adjusted R2 = 0.67). Body mass index accounted for 23.13% of the total variance, followed by vertical jump (22.78%), relative fat (18.09%), grip strength (14.43%), and torso angle during an overhead squat (0.92%). The use of these 5 easily administered field tests is potentially useful as a screening tool for elite American junior men weightlifters. [ABSTRACT FROM AUTHOR]

This investigation estimated the amount of variance in voluntary in vivo muscle performance that can be explained by relative myosin heavy chain (MHC) isoform expression. The role of the relative expression of these proteins in relation to in vitro force and velocity performance is well understood, but the in vivo model is less clear. Twenty-two men and women (mean ± SD age, 27 ± 6 years) performed isometric knee extensor actions in which peak force and rate of force development (RFD) were measured. The results of regression analysis showed that the inclusion of MHC IIb explained a significant (19.9%, p < 0.05) amount of variance in relative peak force (adjusted for muscle mass) and 14.1% of the variance in the first half of the rise phase of the force-time curve (RFD0-50%)(p < 0.1). The addition of MHC I into this model explained a significant (p < 0.05) amount of variance above that accounted for by MHC IIb in RFD (45.4%), RFD0-50% (50.8%), and RFD50-100% (second half of the rise phase of the force-time curve) (37.4%). Since the percentage of MHC IIb is reduced rather quickly with training, these data suggest that peak force may also be affected quickly by training. The percentage of MHC I has a longer course for change with training; therefore, it may be inferred that the greatest changes in RFD variables will likely occur during a longer course. [ABSTRACT FROM AUTHOR]

Strength augmentation has been demonstrated in resistance-trained men subsequent to 4 days of training abstinence. However, this phenomenon was exhibited in an unusual circumstance in which the exercise test (seated heel raise) primarily involved an isolated skeletal muscle (soleus) that is normally comprised almost exclusively of 1 fiber type. It is unclear if similar results would be found for aggregate muscle actions. Therefore, a comparable study was designed with this in mind. Subjects were apparently healthy, young, strength-trained men (n = 25). All performed various tests of bench press strength at the beginning of their last standardized dynamic constant external resistance (DCER) training session. Subjects were subsequently randomly assigned to 1 of 4 groups and repeated the identical tests at intervals of either 2, 3, 4, or 5 days with no intervening training. Strength tests consisted of 1 repetition maximum (1RM) concentric-only isokinetic bench presses performed at 1.49 and 0.37 m·s-1 as well as a 1RM DCER bench press. Measures of peak force and power were obtained from the isokinetic tests and maximum load from the DCER test. Results were expressed in both absolute and relative (to body weight) terms. Subsequent to the 4 abstinence intervals, groups performed similarly (p > 0.05) for all dependent variables. Concurrently, however, a small effect size (ES) was found for the group having a 4-day respite for both absolute and relative expressions of peak force and power at the slowest isokinetic bench press velocity. A small ES was also identified for the group having 2 days of rest for relative peak force at the slowest isokinetic test velocity and for relative DCER strength. Therefore, modest and transient strength augmentation appears likely in aggregate muscle actions following 2-4 days of training abstinence in resistance-trained men, but only at relatively slow velocities. [ABSTRACT FROM AUTHOR]

The ability to generate power is an essential component to achieving optimal performance in several track and field events, particularly the throws, sprints and jumps. The Wingate Anaerobic Test (WAnT) is one of the most established forms of standardized anaerobic power testing. The WAnT is performed utilizing a cycle ergometer and has been shown to be both reliable and valid. Sprinters and jumpers train for power using a combination of running and strength training techniques. The WAnT may be appropriate for testing the running component of training due to its cyclical nature, but it might not be the most fitting test for addressing the more linear weight lifting component. A lift-specific power test could allow for a more comprehensive assessment of the trained status of sprinters and jumpers than a cyclic test alone. The Kansas Squat Test (KST) is a repetitive lifting test that has been designed to measure similar indices of power as the WAnT. To examine the relationship between the WAnT and the KST on measures of Peak Power (PP), Average Power (AP), Minimum Power (MP), Fatigue [% Power Drop (FTG)], and Post-test Lactate (La) for collegiate track and field sprinters and jumpers. Seven male (72.91 ± 10.0kg, 180.70 ± 4.0cm) and seven female (64.43 ± 5.05kg, 171.63 ± 3.55cm) members of a collegiate track and field sprinters and jumpers squad participated in this study. Each participant completed separate familiarization sessions with both the WAnT and KST prior to the data collection sessions. A 1-RM squat was determined using a smith machine, also during an individual session. The data collection sessions were conducted at the beginning of track practice, separated by one week. The WAnT 30-second test was performed using a cycle ergometerwith resistance set at 0.07 kg·BM. The KST was performed using the smith machine and consisted of 15 repetitions of speed squat at a cadence of 1 lift·6 sec-1. The external KST load was calculated using the system mass as ((BM + 1 -RM)·0.70)-BM. KST power measures were determined using an external dynamometer utilizing system mass (BM + KST Load). Pre- and post-test lactate concentrations were also recorded. Pearson correlations between the WAnT and KST are as follows: PP, r = .869∗∗; AP, r = .875∗∗; MP, r = .839∗; FGT, r = -.369; La, r = .110 (∗∗p<0.01; ∗p<0.05). These data indicate that the KST is a feasible alternative to the WAnT for measuring Peak, Average and Minimum Power for sprinters and jumpers. Collegiate track and field sprinters and jumpers train for power using both running and weightlifting exercises. The current study demonstrates a potential testing method that is lift-specific which, when incorporated into a testing battery, may aid in providing a more comprehensive analysis of the athletes'power status. [ABSTRACT FROM AUTHOR]

Power development is a common training goal for many resistance exercisers. Because strength coaches attempt to meet these goals by manipulating the number of repetitions, sets, and intensity, it is important to understand how each of these variables alter movement power. The purpose of this study is to determine how average power changes across 5 sets of squats in 3 different lifting protocols. Seven healthy recreationally trained males (21.4 ± 1.67 years, 72.1 ± 2.0 in., 202.9 ± 21.4 lbs.), who had squatted regularly, completed each of three speed squat (emphasizing speed of the concentric phase) protocols in randomized order and on non-consecutive days. The three testing protocols consisted of 5 sets of 10 repetition at 30% of 1RM; 5 sets of 5 repetitions at 70% of 1RM; and 5 sets of 3 repetitions at 90% of 1RM. Power measures accounted for system mass (bar weight + body mass) instead of merely the bar mass. Set average power (SAP) was calculated as the mean of the repetition average power. Resting and post exercise lactate was also measured. Two way repeated measures ANOVA examined the effect of load and set number for SAP. Post hoc tests of within-subject contrasts using Tukey's LSD procedure were also performed. A separate repeated measures ANOVA tested for differences in lactate measures between the three protocols. Lactate measures were not significantly different between the three testing protocols. Mean SAp ± SE was 1040 ± 78.9 for the 90% load, 1301 ± 87.4 for 70% load, and 1518.5 for the 30% load. There was a significant main effect for load (F = 10.23, p = 0.004), but not for set (F= 0.883, p= 0.520). The average power was lower for the 90% protocol than for the 30% protocol (F= 28.96, p<0.01), but there was no difference between average power produced at the 70% and 30% loads or the 70 % and 90% protocol. A significant interaction (F= 4.98, p< 0.001) was found. A post hoc analysis indicated that at the 90% load the average power for each set decreased from sets 1 to set number 5, while in the 30% protocol SAP significant increased in set 5 compared to set 1. Resistance load appears to affect power fatigue across five sets of resistance exercise. The heaviest load had the highest power fatigue, while the moderate or 70% load did not show any evidence of power fatigue. It should also be noted that five sets at 30% 1RM produced a warm-up effect in that SAP increased from set 1 to set five. At the intensities most frequently utilized to develop power, there is no evidence of decreased power over 5 sets of speed squats. Practitioners attempting to train for power at higher loads (i.e. 90%) may wish to limit the number of sets of such exercises in the training program. [ABSTRACT FROM AUTHOR]

The barbell squat is a commonly used resistance training exercise for the lower limbs that uses and strengthens the muscles surrounding multiple joints of the lower limbs, and as such is considered one of the most basic resistance training exercises. For this reason, previous studies have examined the relationships between quadriceps activity and stance width, knee flexion angle, or tibial rotation angle during the squat exercise. However, there is a lack of studies examining the effects of different stance widths and the effect on power productions during squat training. The purpose of this study was to examine whether using different width stances 　 influenced maximal power production while performing the barbell squat exercise. Eight trained male (means ± SD, age 21.1 ± 2.1 year, height 171.4 ± 6.8 cm, body mass 80.0 ± 13.4 kg) volunteered as subjects for this study. Squat power was assessed, utilizing four different stance widths while exercising with 60% 1 RM loads. Power was measured using an external dynamometer attached to the barbell, (Myotest, Inc., Switzer-land). Since the barbell COM and the body COM travel similar distances, system mass (body mass + barbell mass) was used for all power calculations. The squat stances used were 1) feet 50% bi-acromialthe, 2) feet 100% bi-acromial width, 3) feet 150% bi-acromial width, and 4) feet 200% bi-acromial width. For each of the four different stance widths, the subjects performed three reps at maximal concentric velocity. The concentric pahse started when the posterior thigh was parallel to the ground. The Friedman test was used to determine significant differences in power between the four stances. The level of significant for all statistical analyses was p < 0.05. Resulting power values were expressed normalized to power using the 100% bi-acromial width stance, and expressed as a percentage. Maximal squat power occurred using the 150% bi-acromial width stance (128.4 ± 32.5%), and was significantly higher than the squat power using 50%(97.5 ± 14.3%), 100% and 200%(101.2 ± 16.2%) bi-acromial width stances. These results indicate that altering the stance widths during the barbell squat exercise result in different levels of power production different. The effect of barbell squat stance width needs to be considered when coaches and trainers measure their athletes' 1RM or assess power production during that exercise. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine the mechanomyographic (MMGRMS) and electromyographic (EMGRMS) amplitude vs. force relationships of the vastus lateralis (VL) for aerobically-trained (AT), resistance-trained (RT), and sedentary individuals (SED). Five RT (mean ± SD age = 23 ± 3 yrs; body mass = 101 ± 37 kg; height = 176 ± 8 cm), 5 AT (32 ± 5 yrs; 67 ± 4 kg; 176 ± 2 cm), and 5 SED (23 ± 4 yrs; 93 ± 32 kg; 180 ± 5 cm) men volunteered to perform two 6-s isometric ramp muscle actions from 5% to 100% of their maximal voluntary contraction (MVC) while MMG (m·s-2) and EMG (μV) signals were recorded from the VL muscle. Thigh skinfold measurements and Bergstrom muscle biopsies were taken from the VL. The muscle samples were analyzed for myosin heavy chain (MHC) isoform content. Simple linear regression models were fit to the natural log-transformed EMGRMS and MMGRMS vs. force relationships. The slope (b term) and the antilog of the Y-intercept (a term) were calculated for each relationship. For %MHC, the AT group had a greater percentage of type I fibers than the RT and SED groups (p ≤0.05). The RT group had a greater percentage of type IIa fibers than the AT group (p ≤0.05), and the SED group had a greater percentage of type IIx fibers than the AT and RT groups (p ≤0.05). For both the log-transformed EMGRMS and MMGRMS vs. force relationships, the mean a term for the AT group was higher than the RT and SED groups (p ≤0.05). For the log-transformed MMGRMS vs. force relationships, however, the b term for the AT group was lower than the RT and SED groups (p ≤0.05). There were no differences (p >0.05) among the b terms of the AT, RT, and SED groups for the log-transformed EMGRMS vs. force relationships. In addition, the mean skinfold for the SED group was higher than the AT group (p ≤0.05) (AT = 8.7 ± 2.2mm, RT = 15.4 ± 7.6mm, and SED = 25.4 ± 9.2mm). The group-related differences among the a terms for both the log-transformed EMGRMS and MMGRMS patterns might be best explained by the group differences in skinfold thickness. However, the fact that the AT group had a lower mean b term for the log-transformed MMGRMS vs. force relationships may suggest that the differences in motor control strategies between individuals with predominantly type I vs. type II fibers in the vastus lateralis could be detectible with the MMG signal, but not EMG. The lower b term for the AT group suggested that the MMG-force relationship may have been sensitive to the earlier achievement of rate coding, whereas the RT and SED groups relied more on motor unit recruitment to reach higher force levels. The b terms from the EMGRMS vs. force relationships were unable to differentiate among the groups. The log-transformed MMGRMS, but not EMGRMS, vs. force relationships may be useful as non-invasive measurements to determine the onset of rate coding, which may differ among muscles that are predominantly type I vs. type II fiber types. Therefore, the MMG signal may offer an attractive, simple technique for examining changes in the motor control strategies that govern incremental isometric force production. [ABSTRACT FROM AUTHOR]