International Journal of Strength and Conditioning
International Journal of Strength and Conditioning (IJSC) The International Journal of Strength and Conditioning (IJSC), presented by the International Universities Strength and Conditioning Association (IUSCA), is a leading peer-reviewed academic journal dedicated to advancing research in sports science, sports performance, and strength & conditioning. As a Diamond Open Access journal, the IJSC ensures that all published research is freely accessible to the global community, fostering collaboration and innovation. Our mission is to provide high-quality, impactful research that bridges the gap between academia and practice. This mission is made possible through the generous support of organizations, institutions, and individuals who share our commitment to advancing the fields of sports performance and exercise science. Key partnerships with organizations such as JISC and LYRASIS enable us to maintain our open access model and ensure the sustainability of the journal. As a non-profit organization, the IUSCA relies on community and partner support to continue delivering free, world-class research to the strength and conditioning community. If you find value in the IJSC, please consider: Joining the JISC or LYRASIS schemes, or Making a tax-deductible donation to support our mission and the open access movement. ISSN: 2634-2235 International Universities Strength and Conditioning Association (IUSCA)
International Universities Strength and Conditioning Association
Authors retain copyright of their work, granting IJSC a license to publish and distribute. All articles are distributed under the Creative Commons Attribution 4.0 License. We clearly state any fees associated with submissions or access for readers. For copyright or licensing queries, stakeholders can reach out to journal@iusca.org.
A Framework Guide for the Selection of External Load Metrics in Ice Hockey
External workload monitoring has become commonplace in many sports, with staff looking to leverage the information gained to manipulate practice volume and intensity, hoping to maximize player readiness, minimize fatigue, and reduce the risk of injuries. However, with the increase in availability of technology to facilitate this, practitioners are faced with an overwhelming selection of metrics to choose from. Collinearity, contradiction and the accurate quantification of relative metrics risk creating confusion, and therefore it may benefit practitioners to have some guidance to help in the process of metric selection. This framework aims to provide clarity in the underpinning theory, history and development of external workload monitoring practice, a series of questions for reflective practitioners to consider, and evidence-based practical suggestions for its use.
Copyright (c) 2026 Steven Nightingale, Jonathan Hughes, Mark De Ste Croix, Craig Pfeifer https://creativecommons.org/licenses/by/4.0
Effects of Optimum Power Load vs Mixed Model Training Methods on Lower Limb Strength and Dynamic Performance in Female Athletes
Training with optimum power load (OPL) was shown to result in improved lower limb strength. However, recent study has recommended using the mixed model training (MMT) method which involves frequent varying of training loads. As the training adaptations to OPL and MMT training methods have not been directly compared, hence, the purpose of this study was to compare the effects of OPL and MMT on lower limb neuromuscular adaptations. Seventeen female athletes (age: 22±2.9 years, height: 162.7±5.2 cm, bodyweight: 60.5±9.6 kg) were randomly assigned to either MMT or OPL training (OPLT) group. Both groups performed similar training program twice a week for six weeks. However, MMT performed the loaded CMJ exercise at -15-20% and +20-25% of OPL, while OPLT performed it at OPL. Pre- and post-test included CMJ, 5-0-5 change of direction test (505 COD), 20-m sprint and isometric mid-thigh pull (IMTP). Both groups showed significant improvement in CMJ height (MMT: P=0.025, g=0.48, OPLT: P=0.003, g=0.72), 505 COD (MMT: P<0.001, g=1.12, OPLT: P=0.006, g=0.36), 20-m sprint (MMT: P<0.001, g=0.65, OPLT: P=0.002, g=0.28), IMTP peak force (MMT: P<0.001, g=0.66, OPLT: P<0.001, g=0.46) and IMTP force at 100 ms (MMT: P=0.019, g=0.66, OPLT: P=0.001, g=0.60). Only MMT significantly improved CMJ mean propulsion force (P=0.004, g=0.34), a variable that contributes to greater jump height. While OPLT resulted in greater effect for CMJ height, MMT resulted in greater effect for 505 COD, 20-m sprint and IMTP performance. These findings suggest that frequent varying of resistance may induce greater neuromuscular adaptations.
Copyright (c) 2026 Terence Kwee Hao Chua, Pui Wah Kong, Danny Lum https://creativecommons.org/licenses/by/4.0
The Reliability and Validity of Isometric Midthigh Pull Measures Obtained from a Portable Isometric Dynamometer
The purpose of this investigation was to establish the reliability and concurrent validity of measures of peak and early force production obtained from a portable isometric dynamometer (PID). Twenty resistance trained males completed one familiarization and two isometric mid-thigh pull testing sessions separated by 48-72 hrs. During testing sessions data was simultaneously collected from the PID and force plates (FP) both sampling at a frequency of 1000 Hz. Measurements of peak force (PF) and force at 100 ms (Force100) and 200 ms (Force200) obtained from both the PID and the FP demonstrated acceptable reliability (ICC’s = 0.793-0.966; CV% = 2.7-9.2%). However, PF was significantly and meaningfully greater (P < 0.001; d = 1.00) 1.27% greater when obtained from the FP compared to the PID. In contrast, Force100 obtained from FP was significantly lower to that obtained from PID by 229% (P < 0.001; d =3.96). Similarly, Force200 obtained from FP was significantly lower to that obtained from PID by 38.87% (P < 0.001; d = 1.43). Whilst the measures of force production obtained from the PID was shown to have acceptable reliability they displayed questionable validity, particularly with respect to measures of early force production.
Sport Science; Strength and Conditioning
Copyright (c) 2025 Danny Lum, Lachlan P. James, Luke Stutter, Scott Talpey https://creativecommons.org/licenses/by/4.0
Power! A Field Based Testing Resource for Strength & Conditioning Personnel
Power may be the most vital physical trait towards successful sport performance. Whether competing in team sports such as basketball and rugby; individual sports including track and field events, tennis, and golf; endurance based events encompassing cross country skiing, marathon running, and long distance swimming; or even tactical occupations, power development and maintenance is crucial to an athletes’ success. The specific power component most vital to success should be identified, monitored, and tested to ensure continued development and/or maintenance throughout a competition calendar. By conducting a needs analysis, the specific contributions of power to a given sport can be determined. Equally important as knowing how to develop power, is also knowing what economic field based tests are available to accurately assess athletic development. The purpose of this article is to provide strength and conditioning coaches (SCC) across numerous levels/populations and having various levels of funding, with a brief overview, categorization and coaching resource for the vast array of field testing methods available to assess and monitor whole, upper, and lower body power.
Copyright (c) 2025 Ian Bonder, Dr. Mike Waller, Marc Tangeman, Dr. Andrew Shim https://creativecommons.org/licenses/by/4.0
A Retrospective Self-Reported Audit of Injuries Amongst Grappling Athletes Competing in the United Kingdom
Purpose: This study aimed to estimate the incidence, prevalence, type, and mechanism of injuries among grappling athletes in the United Kingdom (UK) across the following disciplines: Brazilian Jiu-Jitsu (BJJ), Judo, Catch Wrestling, Sambo, and Mixed Martial Arts (MMA). Methods: A retrospective, self-reported survey, delivered via JISC online survey software, was used to record the following information for all injuries sustained over the previous 12-month period: mechanism of injury, environment, severity, recurrence and body region. Additionally, injury diagnosis was reported where possible. Injury incidence for training exposure was calculated based on hours trained per week, while competition exposure was based on the number of bouts participated in during the year. One variable chi-square tests (X2) were used to calculate if observed values were significantly different from expected values. Results: A total of 341 grappling athletes, 243 males and 97 females, with one participant preferring not to state gender (32 ± 9.3 years), completed the study over a 3-month period. The competition incident rates (IR) (24.16/1000 AE) were significantly higher than training (2.97/1000 AE). The knee was the most frequently injured site (24.5%). Ligament sprains were the most commonly diagnosed injury (24.3%). Most injuries occurred during practice sparring (65.8%), with the leading mechanisms being submission attempts and takedowns. Major injuries (>28 days recovery) accounted for 49.5% of all cases. BJJ exhibited the highest injury rate (3.49/1000 AE); patterns varied by discipline and gender. Conclusion: Grappling sports pose a substantial risk of injury, particularly to the knee. Structured training, medical support, and tailored injury risk reduction programs should now be explored to enhance athlete safety.
Copyright (c) 2026 Jonathan Bell, Eleanor Travis, Ashley Jones https://creativecommons.org/licenses/by/4.0
Development of an Independent Regulatory Council for the International Qualification Framework: International Universities Strength and Conditioning Association Position Statement
The establishment of the International Qualification Framework (IQF) represented a seminal advancement towards standardising education and certification levels in the profession of strength and conditioning (S&C). By providing a standardised and internationally unified structure, the IQF directly addresses the long-standing disparities and inconsistencies noted in education and qualification recognition globally. However, the credibility and effectiveness of such a global qualification framework depends upon robust policies and detailed independent regulatory oversight. The IQF Independent Regulatory Council (IQF-IRC) has therefore been established as an autonomous body, specifically designed to oversee the IQF including its education, accreditation, and certification processes. This position statement outlines the governance structure, core responsibilities, professional relevance, and strategic objectives of the IQF-IRC. It will also discuss the benefits of voluntary alignment by global S&C organisations, ultimately fostering a cohesive and universally accepted education and accreditation system that can be presented to the wider industry and public.
Copyright (c) 2025 Andrew Langford, Aden Flannagan, Stephen P. Bird, Paulo Marchetti, Timothy J. Piper, David Morley https://creativecommons.org/licenses/by/4.0
Position-Specific Benchmarks for Jump and Reach Metrics in the National Basketball Association Draft Combine
This study analysed data from the NBA draft combine and aimed to establish position-specific normative data for jump and reach performance to support coaches in better assessing the jumping ability of basketball players. Data on body height with shoes, standing reach (STReach), vertical jump reach (VJReach), and running jump reach (RJReach) were obtained from publicly available sources for 1,048 players who participated in the NBA draft combine between the 2004-05 and 2022-23 seasons. Vertical jump height (VJHeight), running jump height (RJHeight), and run-up effect (RE) were calculated. These variables were then compared across five playing positions; point guard, shooting guard, small forward, power forward, and center and position-specific percentile scores were generated to create normative data. Results showed that RJReach significantly increased from guards to centers (p < .05), primarily reflecting positional differences in anthropometry. Notably, guards demonstrated significantly higher VJHeight, RJHeight, and RE (p < .05) compared to power forwards and centers, indicating that shorter players may compensate for their height through enhanced vertical jump and RE. Furthermore, height and STReach progressively increased from guards to centers, highlighting the contribution of anthropometric, non-trainable characteristics. VJReach and RJReach increased across positions, and this increase was significant between all positions but power forwards and centers. RE was higher in guards and forwards than in centers. These results imply that RE may capture unique, trainable aspects of jump performance. This study presents position-specific benchmarks for jumping ability, offering strength and conditioning coaches practical reference values to assess players’ strengths and weaknesses and to design tailored training programs.
Copyright (c) 2026 Hiroki Ogata, Henderson Frederick, Daichi Yamashita https://creativecommons.org/licenses/by/4.0
Concurrent Validity and Reliability of the My Jump Lab Smartphone Application for Break Point Angle Assessment in the Nordic Hamstring Exercise
The Nordic Hamstring Exercise is widely used to prevent muscle strain injuries. Although isokinetic dynamometry is considered a gold standard for assessment, it is often impractical in many settings, due to several reasons. A cost-effective alternative for physical evaluations of the same muscle could be Smartphone-based, which have greatly increased in recent years due to technological advancements. This study aims to assess the concurrent validity and inter-rater reliability of the My Jump Lab smartphone application in measuring the break point angle (BPA) during the Nordic Hamstring Exercise. Twenty-four healthy participants were recruited for this study and performed five repetitions of the nordic hamstring exercise, while being recorded via smartphone for BPA estimation. The same exercise was compared with kinematic analysis, as reference method. Concurrent validity was assessed by Pearson’s product-moment correlation coefficient and Bland-Altman Plots, while inter-rater reliability was analysed by intraclass correlation coefficient (ICC), coefficient of variation (CV) and standard error of measurement (SEM). Results revealed a very high and significant level of correlation (r > 0.9, p< 0.001) for break point angle measurements, with small proportional bias. The app showed excellent inter-rater reliability (ICC >0.9), with very small variations (CV ≈ 1%) and SEM lower that 1.3 degrees. These outcomes suggest that My Jump Lab is a valid and reliable tool for BPA assessment, that can be used confidently to assess hamstring muscle strain in a simple, portable and practical manner.
Exercise Science/Exercise Physiology - Strength and Conditioning/Human Performance
Copyright (c) 2025 Amandio Dias, André Gomes, Diogo Nogueira, Leonel Correia, Rodrigo Trindade https://creativecommons.org/licenses/by/4.0
Measuring Impulse-DSI and its Derivatives Via the Isometric Belt Squat: Assessing Relationships with Sprint Ability Among Division 1 Team Sport Athletes
The dynamic strength index (DSI) is a common athlete profiling tool that has traditionally been derived as the ratio between the peak force in the isometric mid-thigh pull (IMTP) and the countermovement jump (CMJ) to identify ballistic strength deficits. Recently, an impulse-based DSI (iDSI) has been proposed for the relevance of impulse metrics in explosive sports. Furthermore, the isometric belt squat (IBSq) may be a superior alternative to the IMTP for measuring lower body force potential owing to its removal of the torso and upper limb involvement. The purpose of the current study was to assess the reliability of two novel IBSq and CMJ 200ms impulse metrics. Furthermore, we assessed the individual relationships and predictive utility of the DSI derivatives and 40m sprint performance. 43 Division 1 team sport athletes (30 males and 13 females) were recruited. Reliability was assessed using the intraclass correlation coefficient (ICC) and the coefficient of variation (COV). The relationships between DSI and iDSI derivatives, 0-10m, 10-30m, and 30-40m split times were assessed using Pearson’s correlation coefficient and stepwise regression. The IBSq and CMJ impulses demonstrated acceptable reliability (ICC > .93, COV < 9.6%). IBSq and CMJ impulses explained up to 56% of the variance in 0-10m time (p <.002) and up to 49% of the variance in 30-40m time (p <.0001). The IBSq-derived iDSI score may be a reliable and accurate test for predicting sprint performance among Division 1 team sport athletes. Practitioners may monitor iDSI derivatives to enhance training decisions relevant to sprint speed.
Copyright (c) 2026 Matthew Ward https://creativecommons.org/licenses/by/4.0
Profiling the Physical Conditioning Attributes of Young Male Gaelic Football Players: From Adolescence to Adulthood
This study assessed the anthropometry and physical conditioning attributes of young male inter-county (national level) Gaelic football players, comparing possible differences according to age categories (under-14 [U14] to under-21 [U21]) and position. In total, 3547 assessments were undertaken in 2588 players across a 10-year period (2013 to 2023). Assessments included anthropometry (stature, body mass, sum of 3 skinfolds), flexibility (sit and reach test), muscular power (countermovement jump and standing long jump), running speed (5-m and 20-m), muscular endurance (maximum push ups) and aerobic capacity (yo-yo intermittent recovery test level 1 [YYIRT1]). Increases were demonstrated when comparing age categories from U14 to U21 for anthropometry (e.g., height [cm] +5.7%), muscular power (e.g., Standing long jump [cm] +16.1%). running speed (e.g., 5 m speed [s] -4.8% from U14 to U20), running momentum (e.g., 20 m momentum [kg.ms-1] +41.5% from U14 to U20), muscular endurance (push-ups [n] +107.7%), flexibility (sit and reach [cm] +36.0%) and aerobic capacity (YYIRT1 [m] +42.3%). When comparing positions, goalkeepers and midfielders were taller and heavier than backs and forwards, respectively. Additionally, midfielders displayed superior aerobic conditioning when compared with other positions, while goalkeepers displayed significantly lower aerobic conditioning. These findings offer comparative data of young Gaelic football players from varying age categories (U14 to U21) which are further classified according to positions. Practitioners may utilize this data to inform player identification processes, characterize position-specific benchmarks and monitor physiological adaptations in young players.
Copyright (c) 2025 Lorcan Daly, Cathal Cregg, Daniel Forde, Ciarán Catháin, David Kelly https://creativecommons.org/licenses/by/4.0
Strength, Power and Anaerobic Capacities of Male Judo Athletes across Age and Competitive Levels
Purpose: This cross-sectional study evaluated the physiological profiles of judo athletes across age and competitive levels, aiming to identify key physiological determinants of judo success. Methods: Thirty-eight judokas from three age/competitive levels (cadet + junior, non-Olympic senior, and Olympic senior), spanning various weight classes and ages, were assessed for strength, power, and anaerobic qualities. Performance tests included countermovement jump, drop jump, maximal grip strength, and upper body Wingate anaerobic test (WIN) and results were normalized to body mass. Strength values were obtained from the athletes’ self-reported training programs and normalized to competition weight class. Comparisons of the physical measures were made across age/competitive levels and a qualitative evaluation based on success in national vs. international competitions was made within the groups. Results: Significant differences in absolute values were observed between age/competitive level groups; however, most differences disappeared after normalization. The only persistent differences were in relative WIN peak power and relative WIN mean power, which were greater for the senior athletes compared with the cadet + junior group. No significant differences were found between quality levels within the groups. Conclusion: In the within-group analysis, it was not possible to differentiate high vs. low quality level male judo athletes in our cohort. When comparing the three groups, only relative WIN peak and relative mean power were significantly different between groups while other measures lost significance when normalized. This strengthens the notion that anaerobic power and capacity are relevant to judo success.
Copyright (c) 2025 Idan Harat, Dr. Rotem Kislev-Cohen, Dr. David H. Fukuda https://creativecommons.org/licenses/by/4.0
Unlocking Basketball Athletic Performance: Countermovement Jump Rebound (CMJ-RE) Normative Reference Values Derived from Force Plate Data Across Seven NCAA Division-I Power Five Men’s College Basketball Teams
Purpose: This study examined the emerging countermovement rebound jump (CMJ-RE) test as an alternative to the drop jump (DJ) to grade reactive strength abilities in elite basketball players. Normative percentile data, rebound jump filter criteria, novel effort metrics, and reliability statistics were analyzed in order to better define the standards for a high-quality CMJ-RE test and to democratize the measurement of reactive jump testing. Methods: 96 NCAA Division-I men’s college basketball players from seven teams performed the CMJ-RE (bounce-method) on bilateral force plates with hands on hips during the 2023-2024 pre-season. Only 87 players met the quality filter criteria for further analysis (three centers, 31 forwards, 53 guards); the center position was not compared in depth due to the limited sample size. Results: Between forwards and guards, positional differences were found for 37% of the 38 reported jump metrics, with guards showing higher rebound jump heights (JH), all other metrics (p < 0.05) favored forwards. Mean ground contact times (GCT) for both positions were >250 ms. On average for both positions, the first jump in the CMJ-RE was completed at 94% JH of a previously collected standalone CMJ JH; and the second jump was completed at 98% JH of the first CMJ-RE JH. Furthermore, percentile ranges (3rd to 97th) accompanied by qualitative descriptors and a traffic light classification system were reported. Conclusion: Overall, the CMJ-RE (bounce-method) is a reliable alternative to the DJ for assessing reactive strength qualities in elite basketball players and may be more sport-specific, due to players frequently performing subsequent jumps rather than one single effort jump. The normative data prepared in this study should serve as a reference point throughout the evaluation of reactive strength for basketball performance coaches and in the return to play process for sports medicine professionals. Those administering the CMJ-RE should use the filter criteria measures outlined in this paper to ensure quality and effort are being met.
Copyright (c) 2025 Drake Berberet, Adam Petway, Karah Bell, Zach Gillen, Peter Mundy, Henry Barrera, Jason Kabo, Dom Walker, Garrett Medenwald, Braden Welsh, John McMahon https://creativecommons.org/licenses/by/4.0
A Retrospective Analysis of Powerlifting Performances in the U.S. (1995 - 2005)
In this retrospective study, powerlifting performances in the United States from 1995 – 2005 were taken from annual top 100 rankings published in Powerlifting USA magazine. The rankings included results for the squat, bench press, deadlift, and total for each standard weight class during a calendar year. In the current study, average performances for each weight class were compiled for the #1, #10, #50, and #100 ranks. The weights lifted for each category increased as a function of the competitor’s weight class in a curvilinear pattern, with the heaviest classes showing diminishing improvement in weight lifted with increased body weight. When weights lifted were standardized to the lifter’s weight class, a unimodal curve was observed, with maximal values being in the middle weight classes. The lower mass-specific performance in heavier lifters is the basis for Wilks coefficient and other adjustments for comparing performances among different weight classes. This coefficient is a mathematical formula based on a polynomial transformation of a lifter’s weight class. It was derived to compensate for the curvilinear nature of lifting performance as a function of body weight. Based on the patterns documented, it is proposed that part of this flattening of performance can be attributed to systematic differences in body composition across weight classes. During this 11-year period, significant improvements were observed for some lifts, ranks, and weight classes. However, many did not change, while others showed significant declines. These data demonstrate that U.S. powerlifters at the turn of the century were highly competitive, particularly within the middle through the heaviest weight classes. Overall, the lifting performances in the U.S. during this decade provide an historical reference point, from a time before powerlifting records became more widely available via the internet.
Copyright (c) 2026 Scott Medler https://creativecommons.org/licenses/by/4.0
Comparison of Peak Force and Myoelectric Activity of the Anterior and Middle Deltoid at Three Shoulder Angles During Frontal, Diagonal, and Lateral Raise Exercises in Trained Men
The objective of the present study was to compare the peak force and myoelectric activity of the anterior (AD) and middle deltoid (MD) at three different shoulder joint angles during the frontal (FR), diagonal (DR), and lateral raise (LR) exercises in recreationally-trained men. Fifteen resistance-trained men (age: 27±5 years, height: 173±9 cm, total body mass: 81±10 kg) were assigned to this study. Three resistance exercises (FR, DR, and LR) were tested isometrically at three different shoulder joint angles (0°, 45°, and 90°). Peak force (PF) and myoelectric activity (iEMG) were measured for all exercises and shoulder joint angles. A two-way repeated-measures ANOVA (3x3) was used to test differences between exercises (FR, DR, and LR) and shoulder joint angles (0°, 45°, and 90°) for PF. A three-way repeated-measures ANOVA (2x3x3) was used to test differences between muscle groups (AD and MD), exercises (LR, DR, and FR), and shoulder joint angles (0°, 45°, and 90°) for iEMG. All RT exercises presented similar levels of force production and myoelectric activity (AD and MD) regardless of the specific plane of motion (p>0.05). However, the shoulder joint position affected the force production and AD activity without changes for MD.
Copyright (c) 2025 Willy A. Gomes, Josinaldo J. da Silva, Roberto A. Magalhaes, Luis F.M. Teixeira, Rafael C. Paulino, Paulo H. Marchetti https://creativecommons.org/licenses/by/4.0
The Effect of Neoprene Elbow Sleeves on Bench Press and Shoulder Press Performance
Aim: The aim of the present study was to investigate the effects of neoprene elbow sleeves on performance in bench press and shoulder press. Methods: Nineteen resistance trained males and one female (24 ± 4 years; 181 ± 8 cm; 83 ± 11kg) visited the laboratory on four occasions. Participants were randomly assigned in a crossover and counterbalanced design to one of two conditions: with SBD neoprene elbow sleeves and without sleeves. During each visit, participants completed one repetition maximum (1RM) followed by ‘as many repetitions as possible’ (AMRAP) to concentric failure at 85% of 1RM. Test day one and three were bench press; test day two and four were shoulder press. Results: 1RM bench press was higher with sleeves than without sleeves (104.8 ± 17.7 kg vs. 103.2 ± 18.7 kg, p = 0.015). Bench press AMRAP was higher with sleeves than without sleeves (5.2 ± 1.4 vs. 4.1 ± 2.0, p = 0.006). 1RM shoulder press was higher with sleeves than without sleeves (66.0 ± 13.9 vs. 64.0 ± 13.7, p = 0.008). Shoulder press AMRAP was higher with sleeves than without sleeves (5.8 ± 1.3 vs. 4.6 ± 1.2, p = 0.001). No significant differences were observed in mean or peak barbell velocity between conditions (p >0.05). Conclusion: Neoprene elbow sleeves improved 1RM and AMRAP in bench press and shoulder press, but not barbell velocity.
Copyright (c) 2025 Håkon Andre Mehus, Martin Stamnes, Magnus Olderkjær Larsen, Olav Melhus Gomo, Runar Jakobsen Unhjem https://creativecommons.org/licenses/by/4.0
Key Performance Indicators for the Golf Swing in Elite Collegiate Golf Athletes: An Exploratory Study
Golf swing performance has been found to be influenced by health status, physical fitness, and technical abilities. However, as the sport becomes more competitive, athletes and coaches regularly seek novel approaches to optimizing athletic performance. This study sought to identify key performance indicators that are significantly related to golf club head speed within an elite collegiate golf population. Height, weight, vertical and lateral jump, upper-body rotational velocity, club head speed, and swing kinematics for 21 NCAA Division I female (n = 11) and male (n = 10) golf athletes were collected for analysis. Significant differences between female and male athletes were observed for measures of anthropometry, jumping ability, upper-extremity rotational velocity as well as clubhead speed (p < 0.05). Of particular interest were findings that suggest load-velocity profiling as a novel (for the sport of golf) but useful tool to support individualized golf swing profiling and technical improvement approaches. However, no significant differences between groups were observed for any rotational kinematic measure (p > 0.05). Interestingly, a novel assessment of swing kinematics revealed that peak rotational velocities at specific loads relative to an athlete’s body mass were discovered to have a significantly moderate positive correlation with fast club head speed (p < 0.05). Altogether, these findings can be utilized by sports performance professionals to improve the assessment, development, and performance capabilities of golfers interested in enhancing their clubhead speed.
Copyright (c) 2025 Dr. Quincy R. Johnson, Yang Yang, Kira Ziola, Dawei Sun, Jonathan Moore, Paige Sutton, Dr. Andrew C. Fry, Dr. Douglas B. Smith https://creativecommons.org/licenses/by/4.0
Prediction of Maximal Vertical Jumps during the Entire Season in NCAA Division 1 Women Basketball Players
Purpose: The purpose of this study was to develop a prediction model of weekly maximum jump height (JHmax) performance as a measure of readiness from external workload measures during practice and games, measures of volume-load during resistance training, and self-reported sleep quality, stress, and recovery in NCAA Division 1, women basketball players during the entire season. Methods: Twelve female participants (age = 21.3 ± 1.6 yrs; ht = 171.6 ± 7.1 cm; wt = 67.9 ± 5.3 kg) who were cleared for full participation were recruited to participate in the study. Workload (WL) and work intensity (WI) were measured during every practice and game during the entire official season. The following independent variables were entered into a multivariate regression model to predict JHmax performance across each week in the season using a 7-day period prior to assessment: WL, WI, and Work Density (WD) (WL x WI), self-reported sleep quality (SL), stress (STR), and recovery (REC), total resistance training volume-load (RTV), prior week’s JHmax (Sign), week of the season (Week), and pre-season vs in-season (Season). JHmax was the dependent measure assessed prior to the season and every Monday. Results: The resultant model was statistically significant with an r2 of 71 %. All variables were significant predictors of JHmax except SL and REC. Conclusions: A trend of lower WL and RTV and greater WI and STR had a positive effect on the following JHmax. Analyzing the 7-day period prior to JHmax assessment, high WD scores by manipulation of WL and WI six days prior had a positive influence on JHmax while lower scores were warranted the day before the test. High WL with low WI were indicated three days prior. Finally, controlling for the other variables, JHmax tended to decrease across the in-season indicating a need to reduce external loads in the following week when JHmax decreased to enhance recovery.
College Basketball, Load Management, Resistance Training, Readiness
strength and conditioning, sport science, regression analysis
Copyright (c) 2026 Kevin McCurdy, Rasim Muzaffer Musal https://creativecommons.org/licenses/by/4.0
Response to the Comment on our Article: "Explosive is not a Term Defined in the International System of Units and Should not be Used to Describe Neuromuscular Performance"
We thank Schumann et al. (Schumann, Feuerbacher et al. 2024) for their engagement and thoughtful comments on our article (Ide, Silvatti et al. 2023), and the overarching use of terminology in sports science. Academic debate is critical for advancing our field, and we welcome the opportunity to clarify and expand on our arguments. While their comment offers a perspective on practical terminology use, we maintain that the application of “explosive” in scientific literature may be both unnecessary and potentially misleading.
Copyright (c) 2025 Bernardo Ide, Amanda P. Silvatti, Craig A. Staunton , Moacir Marocolo , Dustin J. Oranchuk , Gustavo R. Mota https://creativecommons.org/licenses/by/4.0
Effect of World Lacrosse Sixes Match play on Neuromuscular Performance in International Men’s Lacrosse Players
Sixes lacrosse is a new sport to be included in the 2028 Olympics, however there is limited understanding on the demands of Sixes lacrosse competition. Purpose: To observe the effect of Sixes lacrosse on acute fatigue. Methods: Eleven international male Sixes lacrosse players (24.82 ± 2.58 years, 180.17 ± 8.84 cm, 90.14 ± 7.63 kg) participated within the present study, playing in five competitive matches over three-days. Three countermovement jump (CMJ) trials were performed pre- and post-match. Results: Very large (d = 1.35 [0.51-2.17]) decreases in system weight (SW), a moderate increase in jump height (JH) (d = 0.67 [-0.02-1.31]) and a moderate decrease in average relative braking force (ARBf) (d = 0.68 [-0.03-1.27]) were observed from pre-post one match. A moderate (d = 0.76 [0.07-1.42]) decrease in SW, with a small increase in average relative propulsive force (ARPf) (d = 0.30 [-0.31-0.90]) were observed from pre-post three matches. Very large increases in JH (d = 1.69 [0.73-2.61]) and time to take off (d = 1.43 [-0.40-2.45]) with a large increase in countermovement displacement (d = 1.05 [0.29-1.78]) and a large decrease in ARBf (d = 0.84 [0.13-1.52]), with no meaningful changes were observed for SW (d = 0.03 [-0.56-0.62]), or ARPf (d = 0.04 [-0.56-0.63]) observed from pre-post international tournament. Conclusion: The results of this study have implications on recovery within Sixes lacrosse players during international tournaments. Moreover, the high levels of observed fatigue would likely require a period of restitution following international tournament.
Copyright (c) 2025 Nicholas Ripley, Jack Fahey, Matthew Collier, Paul Comfort https://creativecommons.org/licenses/by/4.0
Inter-Day Reliability of Countermovement Jump Metrics in Elite Academy Soccer Players
The purpose of this study was to determine the inter-day reliability of countermovement jump (CMJ) force plate metrics in elite male academy soccer players. Fourteen players performed 3 CMJ´s on 3 separate days over an 8-day period during a typical in-season competition and training period. Absolute (coefficient of variation (CV)) and relative reliability (interclass coefficient (ICC)) were calculated using two inter-day combinations; condition 1: Monday-Tuesday, condition 2: Monday-Monday and using two data treatment methods; mean of trials (“mean3”) and single trial with the highest Flight Time:Contraction Time (“BestFT:CT”). In the mean3, Monday-Tuesday condition, all CV´s except for peak landing force were < 10%, with most < 5%, while all ICC’s were > 0.75 (good), and most ICC’s > 0.9 (excellent). Several metrics had lower CV´s and higher ICC´s in condition 1 than condition 2 and in mean3 than BestFT:CT. Importantly, in the context of using downward “eccentric” phase metrics in monitoring, eccentric deceleration rate of force development, durations, power and displacement within this phase demonstrated good-excellent absolute reliability (CVs between 2.9% and 7.03%). Overall, CV´s were substantially lower than most previous studies, but similar to investigations involving elite team sport athletes who also perform the CMJ regularly. Our findings suggest that metric reliability is enhanced by this exposure and by a competitive environment, and that reliability data obtained in populations without these characteristics is not generalizable to the elite setting. Practitioners should endeavor to assess inter-day reliability within their team. In-season implementation represents an ecologically valid option.
Copyright (c) 2025 Ben Lonergan, Daniel D Cohen, Sean Williams, Rebecca Lawson, David J Howarth, David M Johnson https://creativecommons.org/licenses/by/4.0
Quantification of Velocity Decrement and Kinetic Profile during 10 metre Resisted Sprinting using the Run RocketTM
The Run RocketTM is used to improve acceleration and maximum velocity sprinting performance. However, no empirical data exist to support its efficacy. Accordingly, this study aimed to examine how incremental Run RocketTM loads effect sprint velocity (Vdec), relative ground impulse and relative peak force. Fourteen recreationally active (13 male, 1 female) participants performed 10 m sprints at three Run RocketTM arbitrary (AU) resistance levels (10, 20 and 30 AU and unresisted sprints). One-way repeated measures ANOVA, and Cohen’s d effect sizes identified significant and meaningful differences between conditions. Run RocketTM induced significant, large (d= >4.50) Vdec across all conditions. First and second step ground contact times showed large effects (d= >2.50) when comparing unresisted sprinting to all Run Run RocketTM conditions. Concomitant moderate increases were observed for first and second step relative horizontal propulsive impulses, while first and second step relative horizontal propulsive forces showed no effect, suggesting Vdec was attributable to increases in ground contact time during resisted sprinting using the Run RocketTM in all conditions. The results indicate most Run RocketTM resistance levels might be too challenging to improve maximum velocity sprinting, yet not challenging enough to improve acceleration. Therefore, lighter Run RocketTM resistances may be preferential.
Copyright (c) 2025 Jacob Kingham, Matt Springham, Samuel Callaghan, Dr. Alex Bliss https://creativecommons.org/licenses/by/4.0
The Current Knowledge and Future Direction into a New Era of Eccentric Training, A Delphi Study
The purpose of the study was to gain a consensus surrounding specific topics concerning eccentric muscle actions and training. Twelve leading researchers and practitioners agreed to conduct the study, of which eleven completed both rounds of the Delphi study. Statements consisted of: defining eccentric training (Question 1) and eccentric overload Question 4), a new construct of time in action, and finally how would they describe an eccentric muscle action. Both a consensus was reached for eccentric training definition: Eccentric training consists of training methods that incorporate just the eccentric phase, or the manipulation of eccentric actions or training with an eccentric emphasis during resistance or plyometric-based training that have two or more contractile phases (concentric, eccentric, isometric), and a classification to muscle lengthening actions consisting of a passive lengthening action, and an active and forced eccentric action (75%). A consensus was reached of a new term of time in action describing the duration of a phase or movement (100%). Finally, a consensus was not reached for a definition of eccentric overload (64%), and that if the term is used researchers are encouraged to define eccentric overload. Future research now needs to assess these concepts on a wider population and for research to investigate some of the concepts raised from the current study.
Copyright (c) 2025 Mr Matthew James Handford, Mr Thomas Bright, Dr Peter Mundy, Prof Jason Lake, Dr Nicola Theis, Dr Timothy Suchomel, Dr Jonathan Hughes https://creativecommons.org/licenses/by/4.0
Fatigue Mechanisms and their Implications in Hypertrophy: A Review
Mechanical tension, the force-velocity relationship, and high motor unit recruitment are all key factors in skeletal muscle fiber hypertrophy. Fatigue mechanisms can attenuate the hypertrophic response and can develop at any step during muscular contractions and in the post-workout period. These fatigue mechanisms can be split into central and peripheral nervous system. Fatigue physiology plays a key role in potentially modulating muscle fiber hypertrophy however they are seldom discussed together. This review aims to bridge the gap between the two domains and bring focus to the importance of appreciating and considering the role fatigue physiology can play in muscle fiber hypertrophy outcomes.
Copyright (c) 2025 Benjamin Cleary https://creativecommons.org/licenses/by/4.0
Does Olympic Weightlifting Enhance Strength, Power, and Speed in Adolescent Rugby Union Players?
This interventional controlled study investigated the effects of Olympic weightlifting (OWL) on strength, power, and speed in adolescent rugby union players. Under-17 rugby union players were divided into two groups (WLG and CON) [n: 46, age: 15.4 (0.5) years, stature: 175 (6.1) cm, body mass: 73.7 (15.6) kg]. The WLG participated in an 8-week OWL program. Pre- and post-intervention assessments measured countermovement jump height, 10m and 30m sprint times, and a 5RM back squat. Results showed no substantial differences between groups at pre- and post-intervention for strength, power, and speed. Strength significantly improved for both groups from pre-to-post. In addition, the WLG demonstrated a greater rate of strength development in comparison to the CON group (MLE = 7.30, SE = 1.83, 95%CI = [3.65, 10.94], t = 3.99, p < 0.001). Power did not present substantial changes between pre and post for both groups. Speed performance decreased from pre to post for both WLG and CON (p < 0.001). Nonetheless, smaller decreases were observed in the WLG for 10m (+0.05 vs +0.09 sec) and 30m (+0.12 vs +0.20 sec) sprints. Furthermore, anthropometrics (i.e., stature and body mass) proved to be important factors contributing to strength, power, and speed development. The study found no clear evidence to support the benefit of OWL in developing strength, power, and speed in adolescent athletes without prior experience with these exercises. However, OWL may enhance absolute strength gains and mitigate speed performance declines in youth rugby players. Stature and body mass significantly affected these performance metrics, highlighting the need to consider individual differences and developmental changes. Continuous assessment and careful adjustment of training programs are crucial during adolescence to account for variations in stature and body mass.
Copyright (c) 2025 Lorenzo Consonni, Marco Zanin, PJ Wilson, Liam Hennessy https://creativecommons.org/licenses/by/4.0
Differences in Muscle Activation and Joint Kinematics Between Deadlift Styles When Performed at High-Intensity Training Loads
The purpose of this study was to compare the conventional (CDL), sumo (SDL) and hex-bar (HBD) deadlift actions at a high intensity training load across a wide range of leg and back muscles to explore which lift has the biggest impact on prime mover musculature. Twelve males (age: 19 ± 2 years; height: 1.81 ± 0.81 m; body mass: 85.64 ± 10.87 kg) performed 3 repetitions of HBD, CDL and SDL at a 90% 1RM intensity. Load lifted, EMG for the Erector Spinae Longissimus, Gluteus Maximus, Biceps Femoris, Semitendinosus, Rectus Femoris, and Vastus Medialis and knee and hip range were compared via effect size magnitude of change. The EMG results showed a general pattern of greater muscle activity, considered a large effect, during the HBD compared to the CDL and SDL, possibly due to the greater absolute load lifted during the HBD. The only anomaly to this was greater EMG activity for the bicep femoris within the CDL compared to the HBD, large effect, and the SDL, moderate effect. This finding was attributed to the greater hip flexion seen in the start position for the CDL compared to other lifts. These findings suggest that the HBD would be the preferred deadlift technique for total muscle recruitment and load lifted for high intensity (90% 1RM) training regimes. However, the CDL would be the preferred lift if bicep femoris muscle activity were a specific targeted requirement.
Copyright (c) 2025 Iain Fletcher, George Maddams, Laura Charalambous https://creativecommons.org/licenses/by/4.0
Which Metrics Can I Monitor? Test-Retest Reliability of Countermovement Jump and Countermovement Rebound Jump Force-Time Metrics in Youth Soccer Players In-Season
Objective measures provide the most effective means of monitoring the magnitude and time course of changes in neuromuscular function (NMF) resulting from physical activity if measurements are repeatable (reliability). The aim of this study was to determine the test-retest reliability of a range of ratio, outcome, strategy, and kinetic force plate metrics for the countermovement jump (CMJ) and countermovement rebound jump (CMRJ) tests in youth soccer players in the in-season period. A test-retest repeated-measures design was employed consisting of two testing sessions separated by 7-days. In each testing session, male youth soccer players (N = 43; age 17.9 ± 0.9 years, height 181 ± 5.8 cm, body mass 72.5 ± 6.8 kg) from full-time English Football League academies (categories 2 and 4) performed three maximal-effort CMJs and CMRJs in a randomised order on a Hawkin Dynamics Inc. force plate system sampled at 1000 Hz. Fifteen out of 25 CMJ, 11 out of 19 CMJ portion, and five out of 19 rebound jump (RJ) portion metrics demonstrated acceptable absolute (coefficient of variation [CV] ≤10%) and relative (intraclass correlation coefficient [ICC] ≥0.75) reliability for youth soccer players in the in-season period. The CMJ test is a feasible and reliable slow stretch-shortening cycle (SSC) test which can be utilised for monitoring acute changes in NMF in youth soccer players in-season. Practitioners should consider applying a combination of CMJ outcome, strategy, and kinetic metrics in their monitoring processes. The CMRJ test is a less feasible yet reliable fast SSC test which can be utilised for monitoring acute changes in NMF in youth soccer players in-season and can be considered an appropriate alternative to the drop jump (DJ) test as it overcame issues in DJ fall height variability identified in previous research, where acceptable reliability was demonstrated in CMJ portion bodyweight and all outcome metrics.
Forty-three male youth soccer players (age 17.9 ± 0.9 years, height 181 ± 5.8 cm, body mass 72.5 ± 6.8 kg).
Copyright (c) 2025 Andrew J. Badby, Paul Comfort, Nicholas J. Ripley, Matthew Cuthbert, Francisco J. Robles-Palazón, Peter D. Mundy, John J. McMahon https://creativecommons.org/licenses/by/4.0
Hex-Bar Deadlift as a Post Activation Performance Enhancement Warm-up Strategy for Golf Club Head Speed
Club head speed (CHS) is a key determinate of golf ball carry distance. Greater carry distance correlates with greater skill. The aim of the present study is to investigate the acute effects of using the hex - bar deadlift as a post activation potentiation enhancement for improving CHS in collegiate golfers. Sixteen (n= 8 females, age: 19.5 ± 2 years, weight 68.66 kg ± 8.6kg, height 168.4 cm ± 12.7 cm, n=8 males, age: 19.75 ± 2 years, weight 70.0 kg ± 9.5kg, height 178.1 cm ± 12.7 cm) division 2 collegiate golfers participated in this randomized crossover study during the off-season. The study was divided into 3 sessions on 3 separate days. Players reported to the training facility and completed a one-repetition maximum (1RM) hex- bar deadlift on day one. Sessions 2 and 3 included two CHS assessments, one with the PAPE protocol and one without. Each session was 5-7 days apart. One CHS test was preceded by a standardized warm-up, while the other was preceded by the same standardized warm-up with the inclusion of the hex - bar deadlift PAPE strategy (3 reps at 60%, 3 reps at 70%, and 3 reps at 85% of 1RM). A paired two-sided t-test revealed an increase in CHS with the PAPE strategy resulting in a mean difference in CHS of +0.8325 mph (p = 0.02447, d = 0.625). In conclusion, the hex- bar deadlift was shown to provide enough stimulus to elicit a PAPE effect and increase CHS in collegiate golfers.
Copyright (c) 2025 Amanda Ehrlich, Parker Dietzel, Merrick Lincoln, Doug Smith, Quincy Johnson, Gena Guerin https://creativecommons.org/licenses/by/4.0
The Effects of an In-Season Athletic Motor Skill Competencies Intervention on Physical Bio-Motor Qualities among Elite Youth Soccer Players
The aim of this study was to evaluate the efficacy of an in-season athletic motor skill competency (AMSC) programme on the physical bio-motor qualities of youth academy soccer players. Thirty-four (n = 34) U14 and U15 male underage academy soccer players were recruited from a League of Ireland (LOI) soccer club. The study was conducted over 10 weeks that included a pre-testing battery, an 8-week intervention, and a post-testing battery. Pre- to post-intervention, the U14 squad experienced significant increases in countermovement jump (CMJ) peak power, and both chin-up three repetition maximum (3RM) and predicted 1RM (p < 0.05, effect size [ES] = 0.15 to 0.25). The U15 squad displayed significant changes in 5m sprint time (p < 0.05, ES = 0.20); CMJ height, peak power, and propulsive impulse (p < 0.05, ES = -0.17 to -0.58). The U15 squad demonstrated a significant improvement in their 5m sprint time compared to the U14 squad (p < 0.05). Additionally, 38% of the U14 squad showed improvements exceeding the smallest worthwhile change (SWC) across seven CMJ variables (jump height, peak power, eccentric duration, RSImod, mean peak force, propulsive impulse, time to take-off). Similarly, 43% of the U15 squad achieved positive changes greater than the SWC in sprint speed, strength, and 5 of the jump variables. This study provides valuable evidence for integrating an AMSC programme into youth soccer training regimens to optimize player development and performance.
Athletic motor skill competencies (AMSC)
Copyright (c) 2025 Gavin Synott, Paul Byrne, Ryan Lisa , Moody Jeremy, John Duggan https://creativecommons.org/licenses/by/4.0
Comparison of Start Detection Methods for the Countermovement Vertical Jump with Arm Swing
Start detection methods for force-time data analyses of the countermovement vertical jump with arms akimbo (CMJ) have been applied to the CMJ with an arm swing (CMJ-AS). However, little is known regarding the implications of different start detection methods on derived CMJ-AS outcome measures. We compared CMJ-AS start locations that were identified by four detection methods: 1) (body weight [BW] ± 5 standard deviations [5SD]), 2) (maximum [max] BW + 5SD or minimum [min] BW – 5SD), 3) (BW ± 2.5%), and 4) (max BW + 2.5% or min BW – 2.5%). Twenty-two collegiate male basketball players (20.23 ± 2.00 yr, 1.99 ± 0.07 m, 93.79 ± 8.48 kg) performed 3 CMJ-AS trials while vertical ground reaction force (vGRF) data was recorded. A one-way repeated measures ANOVA (α ≤ 0.05) supplemented by Cohen’s d effect sizes compared time to takeoff (TTT), unloading phase metrics, and CMJ-AS start vGRF value amongst the methods. TTT was longer for method 1 (0.99 ± 0.16 s) than methods 2 (0.94 ± 0.17 s, p < 0.01, d = 0.29) and 4 (0.92 ± 0.19 s, p = 0.01, d = 0.43). Unloading time was longer for method 1 than methods 2 (p < 0.01, d = 0.16) and 4 (p < 0.01, d = 0.22) and longer for method 3 than method 4 (p = 0.02, d = 0.21). Unloading force and rate of force development were different between methods 1 and 2 (p ≤ 0.01, d = 0.17) and methods 3 and 4 (p ≤ 0.01, d = 0.21-0.22). There was no difference amongst methods in CMJ-AS start vGRF value. Erroneous start identification rate was lowest for method 4 (3.03%). When analyzing the CMJ-AS, max BW + 2.5% or min BW – 2.5% is recommended to improve start detection and avoid compromised unloading phase metrics.
Copyright (c) 2025 Sunny Park, Michael J. Stewart, John R. Harry https://creativecommons.org/licenses/by/4.0
Relative Rest Correlates to Winning Percentage in 2022 National Football League Season: A Preliminary Study
The purpose of this investigation was to examine whether season average relative rest (RR) influences winning percentage (WIN%) in professional American Football. We define RR as the difference in rest intervals between teams from prior games. To address this, we analyzed each game played in the 2022 NFL season (n=271) and calculated rest intervals between each successive game for each team. The rest interval was defined as the number of days between the schedule start for each successive game, with all teams being assigned a rest interval of 0 during Week 1. Each team’s RR was then determined by subtracting the opposing team’s rest interval. The RR for each game for all teams were then averaged across the season. Subsequently, a correlation between season average RR and WIN% was performed and a tertial split in season average RR was conducted to separate teams into HIGH (teams 1-11), MID (teams 12-21) and LOW (teams 22-32). A one-way ANOVA comparing WIN% between HIGH, MID and LOW was then conducted while independent samples t-tests were employed to assess season average RR between teams with records above (WIN) and below 0.500 (LOSE) and those qualifying (PO) and not qualifying (NPO) for the playoffs. Data indicate that a significant positive relationship exists between WIN% and season average RR (r=0.338; p = 0.029). Moreover, successful teams (WIN/PO) had significantly greater season average RR than unsuccessful teams (LOSE/NPO). Therefore, a team’s rest interval, relative to their opponent was associated with the outcome of the competition during the 2022 NFL season.
Copyright (c) 2025 Adam Jajtner, Anthony Pinzone, Yousuf Abu-Amara, Ryan Gant, Jennifer Rivera, Emily Tagesen, Jacob Barkley https://creativecommons.org/licenses/by/4.0