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.

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 XX(X): 000-000, 2023-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.

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.

Differences in countermovement vertical jump force-time metrics between starting and non-starting professional male basketball players

With force plates being widely implemented for neuromuscular performance assessment in sport-specific settings and various force-time metrics being able to differentiate athletes based on their performance capabilities, the purpose of the present study was to examine the differences in countermovement vertical jump (CVJ) characteristics between starting and non-starting professional male basketball players (e.g., ABA League). Twenty-three athletes (height = 199.2 ± 7.7 kg, body mass = 94.2 ± 8.2 kg, age = 23.8 ± 4.9 years) volunteered to participate in the present investigation. Upon completion of a standardized warm-up protocol, each athlete performed three maximal-effort CVJs without an arm swing while standing on a uni-axial force plate system sampling at 1,000 Hz. Independent t-tests were used to examine statistically significant differences (p < 0.05) in each force-time metric between starters (n = 10) and non-starters (n = 13). No significant differences in any of the CVJ force-time metrics of interest were observed between the two groups, during both the eccentric and concentric phases of the movement (i.e., impulse, duration, peak velocity, and mean and peak force and power). Moreover, starters and non-starters demonstrated similar performance on CVJ outcome (e.g., jump height) and strategy metrics (e.g., countermovement depth). Overall, these findings suggest that at the professional level of play, the ability to secure a spot in the starting lineup is not primarily determined by the players' CVJ performance characteristics.

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.

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.

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.

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.

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.

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.

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.

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.

Inter-Device Reliability of a Three-Dimensional Markerless Motion Capture System Quantifying Elementary Movement Patterns in Humans

With advancements in technology able to quantify wide-ranging features of human movement, the aim of the present study was to investigate the inter-device technological reliability of a three-dimensional markerless motion capture system (3D-MCS), quantifying different movement tasks. A total of 20 healthy individuals performed a test battery consisting of 29 different movements, from which 214 different metrics were derived. Two 3D-MCS located in close proximity were utilized to quantify movement characteristics. Independent sample t-tests with selected reliability statistics (i.e., intraclass correlation coefficient (ICC), effect sizes, and mean absolute differences) were used to evaluate the agreement between the two systems. The study results suggested that 95.7% of all metrics analyzed revealed negligible or small between-device effect sizes. Further, 91.6% of all metrics analyzed showed moderate or better agreement when looking at the ICC values, while 32.2% of all metrics showed excellent agreement. For metrics measuring joint angles (198 metrics), the mean difference between systems was 2.9 degrees, while for metrics investigating distance measures (16 metrics; e.g., center of mass depth), the mean difference between systems was 0.62 cm. Caution is advised when trying to generalize the study findings beyond the specific technology and software used in this investigation. Given the technological reliability reported in this study, as well as the logistical and time-related limitations associated with marker-based motion capture systems, it may be suggested that 3D-MCS present practitioners with an opportunity to reliably and efficiently measure the movement characteristics of patients and athletes. This has implications for monitoring the health/performance of a broad range of populations.

Impact of the Anatomical Accelerometer Placement on Vertical Jump Performance Characteristics

With rapid technological development over recent years, the use of wearable athlete monitoring devices has substantially gained popularity. Thus, the purpose of the present study was to examine the impact of the anatomical placement of an accelerometer on biomechanical characteristics of countermovement vertical jump with and without an arm swing when compared to the force plate as a criterion measure. Seventeen recreationally active individuals (ten males and seven females) volunteered to participate in the present study. Four identical accelerometers sampling at 100 Hz were placed at the following anatomical locations: upper-back (UB), chest (CH), abdomen (AB), and hip (HP). While standing on a uni-axial force plate system sampling at 1000 Hz, each participant completed three non-sequential maximal countermovement vertical jumps with and without an arm swing. All devices recorded the data simultaneously. The following variables of interest were obtained from ground reaction force curves: peak concentric force (PCF), peak landing force (PLF), and vertical jump height (VJH). The findings of the present study reveal that the most appropriate anatomical locations to place the accelerometer device when attempting to estimate PCF, PLF, and VJH during a countermovement vertical jump with no arm swing are CH, AB, and UB, and during a countermovement vertical jump with an arm swing are UB, HP, and UB, respectively. Overall, these findings may help strength and conditioning professionals and sports scientists to select appropriate anatomical locations when using innovative accelerometer technology to monitor vertical jump performance characteristics.

Game statistics that discriminate winning and losing at the NBA level of basketball competition

The purpose of the present study was to examine differences in game-related statistical parameters between National Basketball Association (NBA) regular and post-season competitive periods and to determine which variables have the greatest contribution in discriminating between winning and losing game outcomes. The data scraping technique was used to obtain publicly available NBA game-related statistics over a three-year span (2016–2019). The total number of games examined in the present investigation was 3933 (3690 regular season and 243 post-season games). Despite small to moderate effect sizes, the findings suggest that NBA teams’ style of play (i.e., tactical strategies) changes when transitioning from the regular to post-season competitive period. It becomes more conservative (i.e., fewer field goal attempts, assists, steals, turnovers, and points scored), most likely due to greater defensive pressure. Discriminant function analysis correctly classified winning and losing game outcomes during the regular and post-season competitive periods in 82.8% and 87.2% of cases, respectively. Two key game-related statistics capable of discriminating between winning and losing game outcomes were field goal percentage and defensive rebounding, accounting for 13.6% and 14.2% of the total percentage of explained variance during the regular season and 11.5% and 14.7% during post-season competitive periods. Also, overall shooting efficiency (i.e., free-throw, 2-point, and 3-point combined) accounted for 23–26% of the total percentage of explained variance.

Evaluating Novel Methods of Classifying Interlimb Asymmetries Within Collegiate American Football Players

Over the last few years, researchers and sport scientists have expressed an increased interest in the effects of interlimb asymmetry on aspects of sport performance such as jumping, sprinting, and changing direction. This study aimed to evaluate the diagnostic utility of three different means of classifying asymmetry to highlight if a 6-week resistance training intervention can meaningfully reduce levels of asymmetry, and to determine the relation between asymmetry reduction and improvements in change of direction (CoD) performance, if any. Eighteen, division-two collegiate American football skill position players completed all pre- and post-intervention procedures. These procedures involved the completion of the Bulgarian Split Squat (BSS) exercise from which asymmetries in relative average power (Rel.AP), and relative peak power (Rel.PP) were derived. Additionally, participants completed three repetitions within the 505 and L-drill tests to quantify CoD performance. Results from our study show that participants classified as asymmetrical, exhibiting observed asymmetry in Rel.PP scores larger than the sample mean plus one standard deviation, had the greatest likelihood of reducing asymmetry (OR = 6.99, 95% CI: 1.4, 12.5) and improving L-drill performance (OR = 1.33, 95% CI: -2.1, 4.8). Further, our training intervention meaningfully reduced Rel.AP asymmetry (p = 0.027, Cohen's d = 0.73). At the group level, these reductions in asymmetry were accompanied by improvements in L-drill performance that were larger than the sample smallest worthwhile change (SWC). At the individual level, however, change scores in asymmetry and change scores in CoD performance only showed small, non-significant correlations.

Change-Event Steals "Athlete" from "College Athlete": Perceived Impact and Depression, Anxiety, and Stress

Introduction

This research sought to establish the impact of the change-event of COVID-19 on college athletes and members of other campus groups (eg, marching band, eSports, Reserve Officers Training Corps). The specific purpose was to assess the perceived impact and impact on mental health (eg, depression, anxiety, and stress).

Methods

The survey battery presented a total of 37 items. Demographic, sport or group-specific, and academic-related questions were included alongside the assessment of psychological well-being coming from the Depression Anxiety Stress Scale-21.

Results

There were 249 participants completing some or all of the survey battery. It is notable that 172 participants (69.1%) indicated “a lot has changed”. Common one-word responses to the experience surrounding this change-event were feeling disappointment, upset, frustrated, sadness, annoyance, and depression. Life events that conjured similar magnitude of emotion included significant injury, surgery, and losing a loved one. There were no differences by sport for the depression subscale, but 110 participants reported elevated scores and females had a higher mean depression subscale score compared with males. Differences between sports for the anxiety subscale were negated when evaluating Bonferroni correction for multiple tests, but 69 participants reported elevated scores and females had a higher mean anxiety subscale score compared with males. There was no difference by sport for the stress subscale, but 77 participants reported elevated scores and females had a higher mean stress subscale score compared with males.

Discussion

Authors urge the campus and athletics community to be diligent in monitoring the holistic wellness of college athletes and members of other campus groups. Mainly, we contend it is important to consider that COVID-19 is a significant and widespread change-event, and other change-events are known to have significant impact. We should consider that COVID-19 may be acutely and longitudinally impactful to the American college student.

Interlimb Asymmetry Thresholds that Negatively Affect Change of Direction Performance in Collegiate American Football Players

Researchers and strength and conditioning practitioners have had an increased interest in the effects of interlimb asymmetries on different aspects of sport performance over the past couple of years. Interlimb asymmetries have been found to negatively affect performance in key performance indicators (KPI) such as jumping, sprinting, and changing directions, within various sports populations. However, there is no consensus about a meaningful threshold at which asymmetries start to negatively affect KPIs or performance. The aim of this study was to investigate a potentially meaningful threshold for three asymmetry metrics (mean peak velocity [mPV], mean peak power [mPP], mean average power [mAP]) that were extracted from the Bulgarian split squat and found to be significantly related to change of direction performance (via L-drill test) within a sample of collegiate American football players. Receiver operating characteristic (ROC) curves were used to identify asymmetry thresholds for all metrics that discriminated between faster and slower performers in the L-drill. Players with asymmetries over 10.65% (mAP), 14.59% (MPP), and 14.96% (mPV) were identified by ROC curves as more likely to be classified as low performers. These findings may be helpful for practitioners interested in screening athletes for interlimb asymmetries that may negatively affect their change of direction performance.