Investigating the stretch-shortening cycle fatigue response to a high-intensity stressful phase of training in collegiate men's basketball.

Introduction: While using force-plate derived measures of vertical jump performance, reflective of stretch-shortening-cycle (SSC) efficiency is common practice in sport science, there is limited evidence as to which tests and measures may be most sensitive toward neuromuscular fatigue. The aim of this study was to explore the SSC fatigue response to a one-week high-intensity fatiguing phase of training in National Collegiate Athletic Association (NCAA) Division-I basketball players. Methods: The study timeline consisted of three weeks of baseline measures, one week of high-intensity training, and two weeks of follow-up testing. Countermovement jumps (CMJ) and 10-5 hop tests were performed at baseline, as well as at two time-points during, and three time-points following the fatiguing training period, allowing for performance-comparisons with baseline. Results: Compared to the weekly training sum at baseline, during the high intensity training phase, athletes were exposed to very large increases in selected external load metrics (ES = 1.44-3.16), suggesting that athletes experienced fatigue acutely, as well as potential longer lasting reductions in performance. Vertical jump data suggested that in the CMJ, traditional metrics such as jump height, as well as metrics reflecting kinetic outputs and movement strategies, were sensitive to the stark increase in high-intensity training exposure. The 10-5 hop test suggested a fatigue-induced loss of tolerance to ground impact reflected by performance reductions in metrics related to jump height and reactive strength qualities. Discussion: These findings emphasize that when monitoring neuromuscular fatigue, variables and assessments may not be looked at individually, but rather as part of a more global monitoring approach.

Network model of skeletal muscle cell signalling predicts differential responses to endurance and resistance exercise training.

Exercise-induced muscle adaptations vary based on exercise modality and intensity. We constructed a signalling network model from 87 published studies of human or rodent skeletal muscle cell responses to endurance or resistance exercise in vivo or simulated exercise in vitro. The network comprises 259 signalling interactions between 120 nodes, representing eight membrane receptors and eight canonical signalling pathways regulating 14 transcriptional regulators, 28 target genes and 12 exercise-induced phenotypes. Using this network, we formulated a logic-based ordinary differential equation model predicting time-dependent molecular and phenotypic alterations following acute endurance and resistance exercises. Compared with nine independent studies, the model accurately predicted 18/21 (85%) acute responses to resistance exercise and 12/16 (75%) acute responses to endurance exercise. Detailed sensitivity analysis of differential phenotypic responses to resistance and endurance training showed that, in the model, exercise regulates cell growth and protein synthesis primarily by signalling via mechanistic target of rapamycin, which is activated by Akt and inhibited in endurance exercise by AMP-activated protein kinase. Endurance exercise preferentially activates inflammation via reactive oxygen species and nuclear factor κB signalling. Furthermore, the expected preferential activation of mitochondrial biogenesis by endurance exercise was counterbalanced in the model by protein kinase C in response to resistance training. This model provides a new tool for investigating cross-talk between skeletal muscle signalling pathways activated by endurance and resistance exercise, and the mechanisms of interactions such as the interference effects of endurance training on resistance exercise outcomes.

Starters vs. non-starters differences in vertical jump force-time metrics in female professional volleyball players.

As one of the fundamental volleyball skills, countermovement vertical jump (CMJ) has been commonly implemented in the applied sports setting as a non-invasive and time-efficient assessment of athletes' lower-body neuromuscular function. The purpose of the present study was to examine the differences in CMJ characteristics between starters and non-starters within a cohort of professional female volleyball players. Nineteen athletes competing in one of the top European leagues (i.e., SuperLeague) volunteered to participate in the present investigation. Following the completion of a warm-up protocol, each athlete performed three maximal-effort CMJs with no arm swing while standing on a uni-axial force plate system sampling at 1,000 Hz. The following force-time metrics were used for performance analysis purposes: braking phase duration and impulse, eccentric and concentric duration, mean and peak force and power, contraction time, jump height, and reactive strength index-modified. Mann-Whitney U and independent t-tests revealed no statistically significant differences (p > 0.05) during both eccentric and concentric phases of CMJ between the players included in the starting lineup (n = 9) and their substitutions (n = 10), with the effect sizes being small to moderate in magnitude (g = 0.053-0.683). While further research is warranted on this topic, these results suggest that securing a position in a starting lineup at the professional level of volleyball play may be more contingent on the player's ability to proficiently execute sport-specific skills (e.g., blocking, attacking), rather than the performance on the CMJ assessment, considering that the observed values for both groups fall within the desired ranges for this specific population of athletes.

Dose-Response Relationship for External Workload and Neuromsuclar Performance Over a Female, Collegiate, Basketball Season.

ABSTRACT: Philipp, NM, Cabarkapa, D, Blackburn, SD, and Fry, AC. Dose-response relationship for external workload and neuromsuclar performance over a female, collegiate, basketball season. J Strength Cond Res 38(5): e253-e263, 2024-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.

Competitive Season-Long Changes in Countermovement Vertical Jump Force-Time Metrics in Female Volleyball Players.

ABSTRACT: 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.

Strength and Power Thresholds to Identify High and Low Linear Sprint Speed Performers in Collegiate American Football Players.

ABSTRACT: Philipp, NM, Crawford, DA, Cabarkapa, D, and Fry, AC. Strength and power thresholds to identify high and low linear sprint speed performers in collegiate American football players. J Strength Cond Res 38(1): 74-79, 2024-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.

Vertical Jump Neuromuscular Performance Characteristics Determining On-Court Contribution in Male and Female NCAA Division 1 Basketball Players.

While various quantifiable physical attributes have been found to contribute to athletes' performance, there is a lack of scientific literature focused on examining how they relate to success during competition performance. The aim of this study was to investigate different countermovement jump (CMJ)-derived force-time characteristics and their utility in distinguishing high from low performers within a measure of on-court contribution (i.e., minutes per game played). Twenty-nine collegiate athletes (n = 15 males and n = 14 females) volunteered to participate in this investigation and performed CMJs on dual force plates sampling at 1000 Hz, weekly over the course of their basketball season. The athletes' average of their three best test-days across the season was used for further analysis. To identify their on-court contribution, athletes were divided into groups with high and low minutes per game, based on a median-split analysis. The findings suggest that at the overall group level (i.e., both genders), the modified reactive strength index (mRSI) and braking rate of force development (RFD) revealed the greatest between-group magnitudes of difference, with athletes playing more minutes per game showing greater performance. At the team-specific level, the braking RFD, average braking velocity, and mRSI were shown to be the greatest differentiators between groups for the men's team. The women's high-minutes group displayed greater magnitudes of mRSI and jump height. By identifying the neuromuscular qualities seen in top performers within their respective populations, the attributed physical performance underpinning these qualities may be identified, providing practitioners with insights into physical performance qualities and training methodologies that have the potential to influence basketball performance.

Acute influence of resistance exercise on basketball shooting mechanics and accuracy.

The purpose of the present study was to examine the acute impact of resistance exercise on basketball shooting mechanics and accuracy. Ten resistance-trained recreationally active men with previous basketball playing experience (x̄ ± SD; height = 182.6 ± 9.7 cm; body mass = 79.2 ± 13.9 kg; age = 25.6 ± 5.5 years) performed control, upper-body, and lower-body training sessions in randomized order followed by 5 sets of stationary free-throw (4.57 m), two-point (5.18 m) and three-point (6.75 m) basketball shooting drills in 30 min time increments. Each testing session was separated 3-7 days apart. Kinematic variables during both the preparatory and release phases of the shooting motion were derived from a high-definition camera recording at 120 fps positioned 10 m away perpendicular to the participant's shooting plane of motion. Restricted maximum likelihood linear mixed-effects model analysis revealed that a combination of all fixed effects could account for <1% of the total variance in each dependent variable pertaining to basketball shooting mechanics. A 9.9-11.8% decrease in two-point and three-point shooting accuracy was observed immediately following an upper-body training session. However, the observed performance suppression disappeared 30 min post-exercise completion. Overall, the findings suggest that performing upper-body or lower-body resistance training prior to on-court practice sessions has no impact on free-throw, two-point, and three-point biomechanical parameters examined in the present study and a minor acute impact on mid-range and long-range shooting accuracy in male basketball players.

Recovery Methods in Basketball: A Systematic Review.

Although different strategies have been implemented to manage recovery-fatigue status in athletes, there is still a lack of consensus on which recovery protocols have the greatest impact and effectiveness when implemented with basketball players, including both physiological and psychological recovery methods. Thus, the purpose of this systematic review is to: (a) determine which recovery methods attain the greatest benefit in restoring the process of attenuating fatigue and (b) provide sports practitioners with guidelines on how some of the most effective recovery strategies can be used to optimize athletes' recovery and ultimately enhance their performance. Using the PRISMA guidelines, a total of 3931 research reports were obtained through four database searches (i.e., PubMed, Scopus, Cochrane, and Web of Science), from which only 25 met the inclusion and exclusion criteria. The recovery protocols analyzed in this systematic review were: sleep, nutrition, hydration, ergogenic aids, cold-water immersion, compression garments, massage, acupuncture, tapering, mindfulness, and red-light irradiation. The results revealed that all recovery strategies are capable of attenuating fatigue and enhancing recovery in basketball players to a certain degree. However, an individualized approach should be promoted, where a combination of proactive recovery modalities appears to result in the most rapid rates of recovery and athletes' ability to maintain high-level performance. Recovery should be programmed as an integral component of training regimens. Also, cooperation and communication between coaches, players, and the rest of the team staff members are essential in minimizing the risk of non-functional overreaching or injury and optimizing basketball players' on-court performance.

Pre-Post Practice Changes in Countermovement Vertical Jump Force-Time Metrics in Professional Male Basketball Players.

ABSTRACT: 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 seem to be phase specific. Despite a trivial increase in eccentric mean force (920.4 ± 100.2, 929.4 ± 100.0 N), most changes were observed within the concentric phase of the CVJ. The concentric phase duration increased pre-post practice (0.233 ± 0.027, 0.242 ± 0.033 seconds), whereas concentric impulse (262.9 ± 18.8, 258.6 ± 21.6 N·s), peak velocity (2.93 ± 0.22, 2.86 ± 0.22 m·s-1), mean force (2052.4 ± 179.2, 2002.7 ± 188.2 N), mean power (3,165.5 ± 269.5, 3,030.9 ± 326.8 W), and peak power (5,523.4 ± 607.3, 5,246.6 ± 663.7 W) experienced a significant decrease. Moreover, alongside longer contraction time (0.663 ± 0.065, 0.686 ± 0.074 seconds), lower vertical jump height (41.0 ± 6.8, 38.9 ± 6.6 cm) and reactive strength index-modified (0.634 ± 0.113, 0.579 ± 0.111 m·s-1) values were observed post-practice. Overall, these findings may allow practitioners to detect fatigue-induced changes in CVJ force-time metrics in professional male basketball players that can ultimately improve the acute and longitudinal training-adaptation monitoring process.

Kinematic Differences Based on Shooting Proficiency and Distance in Female Basketball Players.

The purpose of the present study was to examine differences in kinematic characteristics between (a) proficient and non-proficient two-point and three-point shooters, (b) made and missed two-point and three-point shots within a proficient group of shooters, and (c) shots attempted from two-point and three-point shooting distances. Eighteen recreationally active females with previous basketball playing experience attempted 10 two-point (5.10 m) and 10 three-point shots (6.32 m) while facing directly to the basket. To eliminate the possible influence of fatigue, each shot was separated by a 5-10 s rest interval. Participants who made ≥50% of their two-point and ≥40% of their three-point shooting attempts were classified as proficient. A high-definition video camera recording at 30 fps and video analysis software (Kinovea) were used to obtain the kinematic variables of interest during both the preparatory phase (PP) and release phase (RP) of the shooting motion. The results indicate that proficient two-point shooters attained less hip and shoulder flexion during the PP and had greater release height and vertical displacement during the RP. Hip angle differentiated made from missed two-point shots within the proficient group of shooters, with made shots being depicted by less hip flexion. Significantly greater vertical displacement was observed in proficient three-point shooters during the RP. Additionally, the greater elbow and release angles separated made from missed three-point shots within the proficient group of shooters. In response to an increase in shooting distance, hip, knee, ankle, and shoulder angles during the PP all decreased. Moreover, an increase in shooting distance caused a decrease in release angle and an increase in vertical displacement during the RP, while the relative release height remained unchanged.

Changes in countermovement jump force-time characteristic in elite male basketball players: A season-long analyses.

Basketball is a sport that is characterized by various physical performance parameters and motor abilities such as speed, strength, and endurance, which are all underpinned by an athlete's efficient use of the stretch-shortening cycle (SSC). A common assessment to measure SSC efficiency is the countermovement jump (CMJ). When performed on a force plate, a plethora of different force-time metrics may be gleaned from the jump task, reflecting neuromuscular performance characteristics. The aim of this study was to investigate how different CMJ force-time characteristics change across different parts of the athletic year, within a sample of elite collegiate male basketball players. Twelve basketball players performed CMJ's on near-weekly basis, combining for a total of 219 screenings. The span of testing was broken down into four periods: pre-season, non-conference competitive period, conference competitive period, and post-season competitive period. Results suggest that basketball players were able to experience improvements and maintenance of performance with regards to various force-time metrics, transitioning from the pre-season period into respective later phases of the in-season period. A common theme was a significant improvement between the pre-season period and the non-conference period. Various force-time metrics were subject to change, while outcome metrics such as jump height remained unchanged, suggesting that practitioners are encouraged to more closely monitor how different force-time characteristics change over extended periods of time.

Regulatory Light-Chain Phosphorylation During Weightlifting Training: Association With Postactivation Performance Enhancement.

ABSTRACT: Chiu, LZF, Fry, AC, Galpin, AJ, Salem, GJ, and Cabarkapa, D. Regulatory light-chain phosphorylation during weightlifting training: association with postactivation performance enhancement. J Strength Cond Res 37(10): e563-e568, 2023-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.

Biomechanical characteristics of proficient free-throw shooters-markerless motion capture analysis.

The winning game outcome in basketball is partially contingent on the team's ability to secure and make more free-throw shooting attempts, especially close to the end of the game. Thus, the purpose of the present study was to perform a comprehensive biomechanical analysis of the free-throw shooting motion to examine differences between (a) proficient (≥70%) and non-proficient shooters (<70%) and (b) made and missed free-throw shoots within the proficient group of shooters. Thirty-four recreationally active males with previous basketball playing experience attempted ten consecutive free-throw shots (4.57 m), with a 10-15 s rest interval between each shot. An innovative three-dimensional markerless motion capture system (SwRI Enable, San Antonio, TX, USA) composed of nine high-definition cameras recording at 120 Hz was used to capture and analyze the biomechanical parameters of interest. Independent t-tests and Mann-Whitney U tests were used to examine a presence of statistically significant differences. The findings of the present study reveal that proficient free-throw shooters performed the shooting motion in a more controlled manner by having significantly lower knee and center of mass peak and mean angular velocities. Also, proficient shooters attained a significantly greater release height and had less forward trunk lean when compared to non-proficient shooters at the time point of the ball release. Moreover, despite being beneficial for improvements in shooting accuracy, our findings suggest that overemphasizing the release height may be in certain instances counterproductive, as it may lead to more missed than made free-throw shots within the proficient group of shooters.

Position-specific differences in countermovement vertical jump force-time metrics in professional male basketball players.

The countermovement vertical jump (CVJ) is one of the most commonly implemented non-invasive and time-efficient testing modalities for lower-body neuromuscular performance assessment. With more practitioners having access to portable force plates, the purpose of this study was to examine position-specific differences in CVJ force-time metrics within a cohort of elite professional male basketball athletes. Twenty-eight athletes competing in top-tier European basketball leagues volunteered to participate in the present study. Following familiarization with testing procedures and a standardized warm-up protocol, each athlete performed three maximal-effort CVJ on a uni-axial force plate system with hands on the hips during the entire movement. To minimize the possible influence of fatigue, each jump trial was separated by an approximately 15-s rest interval. The mean value across three jumps was used for performance analysis purposes. The findings of the present study reveal notable position-specific differences during the eccentric phase of the CVJ, with centers having greater braking impulse, mean force, and mean power when compared to guards. However, when normalized by body mass, the observed differences during the eccentric phase of the CVJ were nonexistent. On the other hand, no significant differences in absolute mean and peak force and power were detected during the concentric phase of the CVJ. Yet, when normalized by the player's body mass, centers demonstrated inferior performance than guards for the same force-time metrics. Overall, these findings may help practitioners obtain a better insight into position-specific differences with regards to CVJ force-time characteristics as well as aid with individually tailored training regimen design.

Sex-related differences in motor unit behavior are influenced by myosin heavy chain during high- but not moderate-intensity contractions.

AIMS: Motor unit recruitment and firing rate patterns of the vastus lateralis (VL) have not been compared between sexes during moderate- and high-intensity contraction intensities. Additionally, the influence of fiber composition on potential sex-related differences remains unquantified. METHODS: Eleven males and 11 females performed 40% and 70% maximal voluntary contractions (MVCs). Surface electromyographic (EMG) signals recorded from the VL were decomposed. Recruitment thresholds (RTs), MU action potential amplitudes (MUAPAMP ), initial firing rates (IFRs), mean firing rates (MFRs), and normalized EMG amplitude (N-EMGRMS ) at steady torque were analyzed. Y-intercepts and slopes were calculated for MUAPAMP , IFR, and MFR versus RT relationships. Type I myosin heavy chain isoform (MHC) was determined with muscle biopsies. RESULTS: There were no sex-related differences in MU characteristics at 40% MVC. At 70% MVC, males exhibited greater slopes (p = 0.002) for the MUAPAMP , whereas females displayed greater slopes (p = 0.001-0.007) for the IFR and MFR versus RT relationships. N-EMGRMS at 70% MVC was greater for females (p < 0.001). Type I %MHC was greater for females (p = 0.006), and was correlated (p = 0.018-0.031) with the slopes for the MUAPAMP , IFR, and MFR versus RT relationships at 70% MVC (r = -0.599-0.585). CONCLUSION: Both sexes exhibited an inverse relationship between MU firing rates and recruitment thresholds. However, the sex-related differences in MU recruitment and firing rate patterns and N-EMGRMS at 70% MVC were likely due to greater type I% MHC and smaller twitch forces of the higher threshold MUs for the females. Evidence is provided that muscle fiber composition may explain divergent MU behavior between sexes.

Salivary Testosterone and Cortisol Changes During a Game in Professional Male Basketball Players.

ABSTRACT: Cabarkapa, D, Eserhaut, DA, Cabarkapa, DV, Philipp, NM, and Fry, AC. Salivary testosterone and cortisol changes during a game in professional male basketball players. J Strength Cond Res 37(8): 1687-1691, 2023-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 (x̄ ± 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.

Intentionally Slow Concentric Velocity Resistance Exercise and Strength Adaptations: A Meta-Analysis.

ABSTRACT: Hermes, MJ and Fry, AC. Intentionally slow concentric velocity resistance exercise and strength adaptations: a meta-analysis. J Strength Cond Res 37(8): e470-e484, 2023-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 = 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.

Repeat sprint fatigue and altered neuromuscular performance in recreationally trained basketball players.

The primary aim of the present study was to investigate how the fatigue induced through a repeat sprint protocol acutely affected different measures of neuromuscular performance. Recreationally trained basketball players (n = 25) volunteered to participate in the study, and performed three countermovement jumps (CMJ), as well as three drop jumps (DJ) prior to a fatiguing repeat sprint protocol. These procedures were repeated two minutes, and 15 minutes, following the protocol. Various force-time metrics were extracted from the jump tasks, and linear mixed models with subject ID as the random factor, and time as the fixed factor were used to investigate changes across the three time points. To account for the performance during the repeat sprint protocol, a second, two factor model was performed with time and repeat sprint ability (RSA) as the fixed factors. Study results indicated that the sample as a whole merely experienced fatigue-induced decreases in jump height from pre-repeat sprint ability protocol (pre-RSA) within the CMJ compared to two minutes post-repeat sprint ability protocol (post-RSA1) and 15 minutes post-repeat sprint ability protocol (post-RSA2), while jump height within the DJ was only significantly different from pre-RSA at post-RSA1. Further, despite the implementation of the fatiguing RSA protocol, over the course of the three time-points, participants seemed to perform the two jump tasks more efficiently, seen through significantly lower contraction times, greater eccentric (ECC) peak power, and greater ECC mean deceleration force within the CMJ following the RSA task. The two-factor model revealed that several significant time*RSA interactions were found for metrics such as ECC peak velocity and peak power in the CMJ, as well as reactive strength index in the DJ. This suggests that the level of RSA influenced changes across CMJ and DJ characteristics and should be accounted for when interpreting fatigue-induced changes in neuromuscular performance.

Fatigue-Induced Neuromuscular Performance Changes in Professional Male Volleyball Players.

The purpose of the present study was to assess pre-post practice changes in countermovement vertical jump (CVJ) force-time metrics and to determine the relationship between internal and external load variables within a cohort of professional male volleyball players. Ten elite athletes competing in one of the top professional European leagues participated in the present study. While standing on a uni-axial force plate, each athlete performed three CVJs immediately prior to the regular training session. Each athlete wore an inertial measurement unit (VertTM) through an entire practice from which the following external load metrics were obtained: Stress (i.e., an algorithm-derived metric used to quantify the percentage of high-impact movements), Jumps (i.e., the total number of jumps performed during the practice session), and Active Minutes (i.e., the total amount of time performing dynamic movements). Immediately post-practice, each athlete completed another set of three CVJs and reported their subjective measure of internal load using a Rating of Perceived Exertion (RPE) scale (Borg CR-10). While no statistically significant differences were observed in any of the force-time metrics examined in the present study pre-post practice (e.g., eccentric and concentric peak and mean force and power, vertical jump height, contraction time, countermovement depth), our findings indicate a strong positive association between RPE and Stress (r = 0.713) and RPE and Jumps (r = 0.671). However, a weak non-statistically significant correlation was observed between RPE and Active Minutes (r = -0.038), indicating that internal load seems to be more dependent on the intensity rather than the duration of the training session for this sport.