International Journal of Strength and Conditioning
type: channel
description: 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)
publisher: International Universities Strength and Conditioning Association
language: en
publication name: International Journal of Strength and Conditioning
issn: 2634-2235
copyright: 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.
items: Development of an Independent Regulatory Council for the International Qualification Framework: International Universities Strength and Conditioning Association Position Statement
items: Concurrent Validity and Reliability of the My Jump Lab Smartphone Application for Break Point Angle Assessment in the Nordic Hamstring Exercise
items: Profiling the Physical Conditioning Attributes of Young Male Gaelic Football Players: From Adolescence to Adulthood
items: Strength, Power and Anaerobic Capacities of Male Judo Athletes across Age and Competitive Levels
items: https://journal.iusca.org/index.php/Journal/article/view/555
items: The Effect of Neoprene Elbow Sleeves on Bench Press and Shoulder Press Performance
items: Key Performance Indicators for the Golf Swing in Elite Collegiate Golf Athletes: An Exploratory Study
items: 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"
items: Quantification of Velocity Decrement and Kinetic Profile during 10 metre Resisted Sprinting using the Run RocketTM
items: Fatigue Mechanisms and their Implications in Hypertrophy: A Review
items: Does Olympic Weightlifting Enhance Strength, Power, and Speed in Adolescent Rugby Union Players?
items: Differences in Muscle Activation and Joint Kinematics Between Deadlift Styles When Performed at High-Intensity Training Loads
items: Which Metrics Can I Monitor? Test-Retest Reliability of Countermovement Jump and Countermovement Rebound Jump Force-Time Metrics in Youth Soccer Players In-Season
items: Hex-Bar Deadlift as a Post Activation Performance Enhancement Warm-up Strategy for Golf Club Head Speed
items: The Effects of an In-Season Athletic Motor Skill Competencies Intervention on Physical Bio-Motor Qualities among Elite Youth Soccer Players
items: Comparison of Start Detection Methods for the Countermovement Vertical Jump with Arm Swing
items: Relative Rest Correlates to Winning Percentage in 2022 National Football League Season: A Preliminary Study
items: Does the Weekly Distribution of Games and Competition Density Affect Training Load in Elite Male Basketball Players Based on their Playing Role?
items: The The Effect of an Off-Feet Conditioning Protocol on Performance and Training Load Response to Intermittent Sprint Training Compared to an Equivalent Running Based Protocol
items: Accumulated Workload, Neuromuscular Fatigue, Wellbeing and Hormonal Variations in Professional Offshore Sailors: A Pre-competition Study
items: The Influence of Eccentric Muscle Actions on Concentric Muscle Strength: An Exception to the Principle of Specificity?
items: Acute Potentiation on Propulsive-Only Jump (POJ) Performance Following Supramaximal Accentuated Eccentric Loading in High School Basketball Players
items: The Validity and Reliability of the My Jump Lab Artificial Intelligence Application
items: Percentile Rankings and Normalization of Performance for Youth International Weightlifting Federation World Championships Competitors
items: New Perspectives in Assessing Pickup Acceleration.
items: The Accuracy of the Titan 1+ 10 Hz Global Positioning System for Measures of Time, Distance, and Top Speed
items: Preparation for Powerlifting Competition: A Case Study
items: Implementing the Reverse Acute to Chronic Workload Ratio Model to Improve Movement Capacity and Roster Availability: An Example Using Data from the NFL
items: The Reliability and Validity of Different Methods for Measuring Countermovement Jump Height
items: Maturation and Physical Performance in National Level Youth Basketballers: Implications for Strength and Conditioning Coaches

Development of an Independent Regulatory Council for the International Qualification Framework: International Universities Strength and Conditioning Association Position Statement
type: item
description: 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.
subject: IUSCA Position Stands and Statements
  topic: section
creator: Andrew Langford
creator: Aden Flannagan
creator: Stephen P. Bird
creator: Paulo Marchetti
creator: Timothy J. Piper
creator: David Morley
rights: Copyright (c) 2025 Andrew Langford, Aden Flannagan, Stephen P. Bird, Paulo Marchetti, Timothy J. Piper, David Morley https://creativecommons.org/licenses/by/4.0
date: 2025-06-03
publication date: 2025-06-03
doi: 10.47206/ijsc.v5i1.582

Concurrent Validity and Reliability of the My Jump Lab Smartphone Application for Break Point Angle Assessment in the Nordic Hamstring Exercise
type: item
description: 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.
subject: Articles
  topic: section
subject: Break point angle
  topic: keywords
subject: Nordic hamstring exercise
  topic: keywords
subject: Mobile application
  topic: keywords
subject: injury prevention
  topic: subjects
subject: Nordic
  topic: subjects
subject: Injury Prevention and Rehabilitation
  topic: disciplines
subject: Exercise Science/Exercise Physiology - Strength and Conditioning/Human Performance
  topic: disciplines
creator: Amandio Dias
creator: André Gomes
creator: Diogo Nogueira
creator: Leonel Correia
creator: Rodrigo Trindade
rights: Copyright (c) 2025 Amandio Dias, André Gomes, Diogo Nogueira, Leonel Correia, Rodrigo Trindade https://creativecommons.org/licenses/by/4.0
date: 2025-10-24
publication date: 2025-10-24
doi: 10.47206/ijsc.v5i1.471

Profiling the Physical Conditioning Attributes of Young Male Gaelic Football Players: From Adolescence to Adulthood
type: item
description: 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.
subject: Articles
  topic: section
subject: Team sport
  topic: keywords
subject: Long term athletic development
  topic: keywords
subject: Physiological adaptation
  topic: keywords
subject: Maturation
  topic: keywords
subject: Youth athletes
  topic: keywords
subject: Strength and Conditioning for Youth
  topic: disciplines
creator: Lorcan Daly
creator: Cathal Cregg
creator: Daniel Forde
creator: Ciarán Catháin
creator: David Kelly
rights: Copyright (c) 2025 Lorcan Daly, Cathal Cregg, Daniel Forde, Ciarán Catháin, David Kelly https://creativecommons.org/licenses/by/4.0
date: 2025-08-08
publication date: 2025-08-08
doi: 10.47206/ijsc.v5i1.456

Strength, Power and Anaerobic Capacities of Male Judo Athletes across Age and Competitive Levels
type: item
description: 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.
subject: Articles
  topic: section
subject: Judo
  topic: keywords
subject: Martial arts
  topic: keywords
subject: Hand Grip
  topic: keywords
subject: Anaerobic performance
  topic: keywords
subject: Combat Sport
  topic: keywords
subject: Wingate test
  topic: keywords
subject: Judo
  topic: subjects
subject: Martial Arts Athletes
  topic: subjects
subject: Elite athletes
  topic: subjects
subject: exercise physiology
  topic: subjects
subject: Wingate test
  topic: subjects
subject: Athletic Performance
  topic: subjects
subject: Talent identification
  topic: subjects
subject: Exercise Physiology
  topic: disciplines
subject: Sport Science
  topic: disciplines
subject: Applied Sport Science
  topic: disciplines
subject: Kinesiology
  topic: disciplines
creator: Idan Harat
creator: Rotem Kislev-Cohen
creator: David Fukuda
rights: Copyright (c) 2025 Idan Harat, Dr. Rotem Kislev-Cohen, Dr. David H. Fukuda https://creativecommons.org/licenses/by/4.0
date: 2025-09-19
publication date: 2025-09-19
doi: 10.47206/ijsc.v5i1.488

https://journal.iusca.org/index.php/Journal/article/view/555
type: item
title: 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
description: 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 cri…
subject: Articles
  topic: section
subject: Force plate testing
  topic: keywords
subject: countermovement rebound jump
  topic: keywords
subject: basketball testing
  topic: keywords
subject: force plates
  topic: subjects
subject: basketball
  topic: subjects
subject: countermovement rebound jump
  topic: subjects
subject: drop jump
  topic: subjects
subject: reactive strength
  topic: subjects
subject: Biomechanics
  topic: disciplines
creator: Drake Berberet
creator: Adam Petway
creator: Karah Bell
creator: Zach Gillen
creator: Peter Mundy
creator: Henry Barrera
creator: Jason Kabo
creator: Dom Walker
creator: Garrett Medenwald
creator: Braden Welsh
creator: John McMahon
rights: 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
date: 2025-10-03
publication date: 2025-10-03
doi: 10.47206/ijsc.v5i1.555

The Effect of Neoprene Elbow Sleeves on Bench Press and Shoulder Press Performance
type: item
description: 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.
subject: Articles
  topic: section
subject: Bench press
  topic: keywords
subject: Shoulder press
  topic: keywords
subject: Muscular performance
  topic: keywords
subject: Ergogenic tool
  topic: keywords
subject: Resistance training
  topic: keywords
subject: SBD
  topic: keywords
subject: Bench press
  topic: subjects
subject: shoulder press
  topic: subjects
subject: sbd
  topic: subjects
subject: muscular performance
  topic: subjects
subject: ergogenic tool
  topic: subjects
subject: resistance training
  topic: subjects
subject: Sport Science; Strength and Conditioning
  topic: disciplines
creator: Håkon Andre Mehus
creator: Martin Stamnes
creator: Magnus Olderkjær Larsen
creator: Olav Melhus Gomo
creator: Runar Jakobsen Unhjem
rights: Copyright (c) 2025 Håkon Andre Mehus, Martin Stamnes, Magnus Olderkjær Larsen, Olav Melhus Gomo, Runar Jakobsen Unhjem https://creativecommons.org/licenses/by/4.0
date: 2025-11-07
publication date: 2025-11-07
doi: 10.47206/ijsc.v5i1.476

Key Performance Indicators for the Golf Swing in Elite Collegiate Golf Athletes: An Exploratory Study
type: item
description: 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.
subject: Articles
  topic: section
subject: vertical jump
  topic: keywords
subject: strength and conditioning
  topic: keywords
subject: college golf
  topic: keywords
subject: sport science
  topic: keywords
subject: Jayhawk Athletic Performance Laboratory
  topic: keywords
subject: golf
  topic: subjects
subject: college
  topic: subjects
subject: Key Performance indicators
  topic: subjects
subject: strength and conditioning
  topic: disciplines
subject: sport science
  topic: disciplines
creator: Quincy Johnson
creator: Yang Yang
creator: Kira Ziola
creator: Dawei Sun
creator: Jonathan Moore
creator: Paige Sutton
creator: Andrew Fry
creator: Douglas Smith
rights: 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
date: 2025-10-17
publication date: 2025-10-17
doi: 10.47206/ijsc.v5i1.490

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"
type: item
description: 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.
subject: Commentaries
  topic: section
subject: Strength and power training
  topic: subjects
subject: Neuromuscular Performance
  topic: subjects
subject: Exercise Science/Exercise Physiology - Strength and Conditioning/Human Performance
  topic: disciplines
subject: Biomechanics
  topic: disciplines
creator: Bernardo Ide
creator: Amanda P. Silvatti
creator: Craig A. Staunton
creator: Moacir Marocolo
creator: Dustin J. Oranchuk
creator: Gustavo R. Mota
rights: 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
date: 2025-02-14
publication date: 2025-02-14
doi: 10.47206/ijsc.v5i1.506

Quantification of Velocity Decrement and Kinetic Profile during 10 metre Resisted Sprinting using the Run RocketTM
type: item
description: 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.
subject: Articles
  topic: section
subject: resisted sprinting
  topic: keywords
subject: acceleration
  topic: keywords
subject: ground impulse
  topic: keywords
subject: Vdec
  topic: keywords
subject: Sprint acceleration
  topic: subjects
subject: kinetic
  topic: subjects
subject: resisted
  topic: subjects
creator: Jacob Kingham
creator: Matt Springham
creator: Samuel Callaghan
creator: Alex Bliss
rights: Copyright (c) 2025 Jacob Kingham, Matt Springham, Samuel Callaghan, Dr. Alex Bliss https://creativecommons.org/licenses/by/4.0
date: 2025-09-05
publication date: 2025-09-05
doi: 10.47206/ijsc.v5i1.485

Fatigue Mechanisms and their Implications in Hypertrophy: A Review
type: item
description: 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.
subject: Articles
  topic: section
subject: Mechanical tension
  topic: keywords
subject: Motor unit recruitment
  topic: keywords
subject: Force-velocity relationship
  topic: keywords
subject: Length-tension relationship
  topic: keywords
subject: Central nervous system fatigue
  topic: keywords
subject: Peripheral fatigue
  topic: keywords
subject: Exercise Science
  topic: disciplines
creator: Benjamin Cleary
rights: Copyright (c) 2025 Benjamin Cleary https://creativecommons.org/licenses/by/4.0
date: 2025-08-22
publication date: 2025-08-22
doi: 10.47206/ijsc.v5i1.381

Does Olympic Weightlifting Enhance Strength, Power, and Speed in Adolescent Rugby Union Players?
type: item
description: 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.
subject: Articles
  topic: section
subject: Strength
  topic: keywords
subject: Power
  topic: keywords
subject: Speed
  topic: keywords
subject: Rugby
  topic: keywords
subject: Olympic weightlifting
  topic: keywords
subject: Long-term athletic development
  topic: keywords
creator: Lorenzo Consonni
creator: Marco Zanin
creator: PJ Wilson
creator: Liam Hennessy
rights: Copyright (c) 2025 Lorenzo Consonni, Marco Zanin, PJ Wilson, Liam Hennessy https://creativecommons.org/licenses/by/4.0
date: 2025-03-21
publication date: 2025-03-21
doi: 10.47206/ijsc.v5i1.399

Differences in Muscle Activation and Joint Kinematics Between Deadlift Styles When Performed at High-Intensity Training Loads
type: item
description: 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.
subject: Articles
  topic: section
subject: Deadlift technique
  topic: keywords
subject: EMG
  topic: keywords
subject: Training recomendations
  topic: keywords
creator: Iain Fletcher
creator: George Maddams
creator: Laura Charalambous
rights: Copyright (c) 2025 Iain Fletcher, George Maddams, Laura Charalambous https://creativecommons.org/licenses/by/4.0
date: 2025-05-30
publication date: 2025-05-30
doi: 10.47206/ijsc.v5i1.396

Which Metrics Can I Monitor? Test-Retest Reliability of Countermovement Jump and Countermovement Rebound Jump Force-Time Metrics in Youth Soccer Players In-Season
type: item
description: 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.
subject: Articles
  topic: section
subject: Sports Science
  topic: keywords
subject: Strength and Conditioning
  topic: keywords
subject: Four Corner Model
  topic: keywords
subject: Physical Corner
  topic: keywords
subject: Profiling
  topic: keywords
subject: Forty-three male youth soccer players (age 17.9 ± 0.9 years, height 181 ± 5.8 cm, body mass 72.5 ± 6.8 kg).
  topic: subjects
subject: Sports Science
  topic: disciplines
subject: Biomechanics
  topic: disciplines
subject: Strength and Conditioning
  topic: disciplines
creator: Andrew Badby
creator: Paul Comfort
creator: Nicholas Ripley
creator: Matthew Cuthbert
creator: Francisco Robles-Palazón
creator: Peter Mundy
creator: John McMahon
rights: 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
date: 2025-06-21
publication date: 2025-06-21
doi: 10.47206/ijsc.v5i1.418

Hex-Bar Deadlift as a Post Activation Performance Enhancement Warm-up Strategy for Golf Club Head Speed
type: item
description: 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.
subject: Articles
  topic: section
subject: Golf Science
  topic: keywords
subject: Strength Training
  topic: keywords
subject: Power Production
  topic: keywords
subject: Intervention
  topic: keywords
subject: Skill-based sport
  topic: keywords
subject: Golf Science
  topic: subjects
subject: Athletic Performance
  topic: subjects
subject: Club Head Speed
  topic: subjects
subject: post-activation performance enhancement
  topic: subjects
subject: Strength & Conditioning
  topic: subjects
subject: Exercise Sports Science
  topic: disciplines
subject: Exercise Physiology
  topic: disciplines
subject: Applied sport and exercise sciences
  topic: disciplines
subject: Kinesiology
  topic: disciplines
creator: Amanda Ehrlich
creator: Parker Dietzel
creator: Merrick Lincoln
creator: Doug Smith
creator: Quincy Johnson
creator: Gena Guerin
rights: Copyright (c) 2025 Amanda Ehrlich, Parker Dietzel, Merrick Lincoln, Doug Smith, Quincy Johnson, Gena Guerin https://creativecommons.org/licenses/by/4.0
date: 2025-09-26
publication date: 2025-09-26
doi: 10.47206/ijsc.v5i1.486

The Effects of an In-Season Athletic Motor Skill Competencies Intervention on Physical Bio-Motor Qualities among Elite Youth Soccer Players
type: item
description: 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.
subject: Articles
  topic: section
subject: Athletic motor skill competencies (AMSC)
  topic: keywords
subject: Youth
  topic: keywords
subject: Soccer
  topic: keywords
subject: Competitive phase
  topic: keywords
subject: Bio-motor qualities
  topic: keywords
subject: Strength & Conditioning
  topic: disciplines
subject: Sport Science; Strength and Conditioning
  topic: disciplines
subject: youth athletes
  topic: disciplines
subject: Soccer
  topic: disciplines
subject: competition
  topic: disciplines
creator: Gavin Synott
creator: Paul Byrne
creator: Ryan Lisa
creator: Jeremy Moody
creator: John Duggan
rights: Copyright (c) 2025 Gavin Synott, Paul Byrne, Ryan Lisa , Moody Jeremy, John Duggan https://creativecommons.org/licenses/by/4.0
date: 2025-09-12
publication date: 2025-09-12
doi: 10.47206/ijsc.v5i1.475

Comparison of Start Detection Methods for the Countermovement Vertical Jump with Arm Swing
type: item
description: 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.
subject: Articles
  topic: section
subject: Countermovement Jump
  topic: keywords
subject: Force-Time Curve
  topic: keywords
subject: Countermovement Jump
  topic: subjects
subject: Force-Time Curve
  topic: subjects
subject: Biomechanics
  topic: disciplines
subject: Sports Science
  topic: disciplines
creator: Sunny Park
creator: Michael Stewart
creator: John Harry
rights: Copyright (c) 2025 Sunny Park, Michael J. Stewart, John R. Harry https://creativecommons.org/licenses/by/4.0
date: 2025-10-31
publication date: 2025-10-31
doi: 10.47206/ijsc.v5i1.472

Relative Rest Correlates to Winning Percentage in 2022 National Football League Season: A Preliminary Study
type: item
description: 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.
subject: Articles
  topic: section
subject: American Football
  topic: keywords
subject: Performance
  topic: keywords
subject: Recovery
  topic: keywords
subject: Sport Science
  topic: disciplines
creator: Adam Jajtner
creator: Anthony Pinzone
creator: Yousuf Abu-Amara
creator: Ryan Gant
creator: Jennifer Rivera
creator: Emily Tagesen
creator: Jacob Barkley
rights: 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
date: 2025-04-18
publication date: 2025-04-18
doi: 10.47206/ijsc.v5i1.403

Does the Weekly Distribution of Games and Competition Density Affect Training Load in Elite Male Basketball Players Based on their Playing Role?
type: item
description: Purpose: The aim of this study was to compare the external workload encountered by Euroleague basketball players based on the weekly game density (ranging from 0 to 3-games per week) and player roles (bench, rotation, and starter). Method: A longitudinal observational study was conducted across two full seasons. The weekly workload was determined by recording PlayerLoad™ using microsensors during basketball practices and estimations for games. A linear mixed model with Bonferroni post-hoc tests was used to compare the workload among weeks and player roles. Additionally, Cohen’s d effect sizes were applied to determine the magnitude of the differences. Results: Starting players consistently experienced higher external workload compared to rotation players and bench players across all weekly configurations. In weeks with more games, especially from Friday to Sunday, starters faced the highest workload, followed by rotation players. Significant differences (p<0.05) were observed both in the total number of games per week and in the specific distribution of games within the week. Conclusion: These findings highlight the substantial impact of game density and player roles on the workload experienced throughout a professional men’s basketball season. Therefore, coaches should take this into account when planning appropriate weekly workloads based on players’ roles within the team roster.
subject: Articles
  topic: section
subject: basketball
  topic: keywords
subject: accelerometry
  topic: keywords
subject: team sport
  topic: keywords
subject: workload
  topic: keywords
subject: week
  topic: keywords
subject: player role
  topic: keywords
creator: Hugo Salazar
creator: Luka Svilar
creator: Julen Castellano
creator: Jairo Vázquez-Guerrero
creator: Enrique Alonso Perez-Chao
rights: Copyright (c) 2025 Hugo Salazar, Luka Svilar, Julen Castellano, Jairo Vázquez-Guerrero, Enrique Alonso Perez-Chao https://creativecommons.org/licenses/by/4.0
date: 2025-03-14
publication date: 2025-03-14
doi: 10.47206/ijsc.v5i1.371

The The Effect of an Off-Feet Conditioning Protocol on Performance and Training Load Response to Intermittent Sprint Training Compared to an Equivalent Running Based Protocol
type: item
description: Training for maximal intensity actions can lead to muscle damage, muscle soreness, and neuromuscular fatigue if not carefully managed. Due to this potential impact, coaches sometimes look to off-feet conditioning (OFC) as an alternative. A training intervention compared an OFC protocol using cycle ergometer sprints with an equivalent running protocol. Seventeen (17) participants volunteered and completed the study. Following baseline testing participants were divided into a cycle (BIKE) or shuttle (RUN) group. Training intervention was 10-12 6 s sprint efforts with 80-seconds recovery. Post testing showed significant time effect for absolute (p=0.045), and substantial change for Mean Power (p=0.0606) for BIKE. There was a significant time effect in the shuttle test (p=0.008) for RUN. Substantial, non-significant improvements in performance were found in 10 m (p=0.261) 20 m time (p=0.307) and Peak Power (p=0.160) for BIKE. RPE was significantly higher in BIKE (p<0.001). Next-day soreness was significantly higher for RUN (p<0.001). Neither intervention negatively affected any measure. The cycle protocol may benefit sprint running performance. This form of training may mitigate the impact of high volumes of run-based training by decreasing eccentric loading thus reducing soreness. OFC may be useful for maintaining performance without adding mechanical stress on the lower body.
subject: Articles
  topic: section
subject: sport
  topic: keywords
subject: conditioning
  topic: keywords
subject: training
  topic: keywords
subject: open-sport
  topic: keywords
subject: testing
  topic: keywords
subject: sport
  topic: disciplines
subject: exercise
  topic: disciplines
creator: Timothy Rogers
creator: Ryan Connell
creator: Jarrod Free
creator: Nicholas Gill
creator: Kim Hebert-Losier
creator: Martyn Beaven
rights: Copyright (c) 2025 Timothy Rogers, Ryan Connell, Jarrod Free, Nicholas Gill, Kim Hebert-Losier, Martyn Beaven https://creativecommons.org/licenses/by/4.0
date: 2025-05-23
publication date: 2025-05-23
doi: 10.47206/ijsc.v5i1.410

Accumulated Workload, Neuromuscular Fatigue, Wellbeing and Hormonal Variations in Professional Offshore Sailors: A Pre-competition Study
type: item
description: This study aimed to comprehensively analyse the distribution of workload (WL) and its multifaceted impact on neuromuscular performance, wellbeing, and stress hormone levels within the professional offshore sailing context. Over a 27-week pre-competition period, ten professional sailors (8 males and 2 females) participated in regular assessments to evaluate their workload and its effects. Weekly workload (WLwk), strain (WLstr), and monotony (WLmono) were quantified using the session-rating of perceived exertion (sRPE), a validated tool for assessing training intensity. To measure subjective markers of recovery, the Hooper-index (HI) was collected weekly, providing insights into the athletes’ perceived recovery status. Furthermore, salivary cortisol (C) levels, indicative of stress response, along with countermovement jump height (CMJ) and maximal strength on bench press (BP1RM), were assessed at the beginning of each training block to evaluate neuromuscular performance changes over time. Significant correlations were identified between the monitored workload indices and various variables. WLwk showed associations with CMJ, BP1RM, HI, and C, indicating a relationship between workload and both physical performance and stress levels. WLmono was correlated with HI, highlighting the impact of workload monotony on perceived recovery status. Similarly, WLstr was associated with CMJ, BP1RM, HI, and C, suggesting that workload strain affects neuromuscular performance, wellbeing, and stress hormone levels. In conclusion, the study suggests that integrating both objective (WLwk, WLstr, WLmono) and subjective (HI) monitoring tools can provide practitioners with valuable insights into optimising performance and managing stress in the demanding environment of offshore sailing.
subject: Articles
  topic: section
subject: Monitoring
  topic: keywords
subject: Fatigue
  topic: keywords
subject: Adaptations
  topic: keywords
subject: Preparedness
  topic: keywords
subject: Performance
  topic: keywords
subject: Sailing
  topic: keywords
subject: Professional Athletes
  topic: subjects
subject: Offshore Sailing
  topic: disciplines
creator: Kilian Philippe
creator: Paillard Thierry
creator: Olivier Maurelli
creator: Jeremy Moody
creator: Prioux Jacques
rights: Copyright (c) 2025 Kilian Philippe, Paillard Thierry, Olivier Maurelli, Jeremy Moody, Prioux Jacques https://creativecommons.org/licenses/by/4.0
date: 2025-02-21
publication date: 2025-02-21
doi: 10.47206/ijsc.v5i1.386

The Influence of Eccentric Muscle Actions on Concentric Muscle Strength: An Exception to the Principle of Specificity?
type: item
description: The principle of specificity suggests that the largest changes in strength occur when training resembles the specific strength test. A one-repetition maximum (1RM) test, which tests the maximal concentric strength, is commonly used as a surrogate for strength adaptation. When separating muscle actions into concentric or eccentric phases, multiple lines of evidence suggest that eccentric muscle actions possess several distinct physiological properties compared with concentric actions. In accordance, there are instances where the increases in 1RM strength test were similar between eccentric-only and concentric-only resistance training. This is at odds with the principle of specificity which suggests that individuals who trained with concentric actions would be expected to have an advantage in that specific task. Although the mechanistic reasons why eccentric-biased training carries over to maximal concentric strength remains to be elucidated, the lack of discernible differences in strength gains with eccentrically-biased training (e.g., eccentric-only and accentuated eccentric training) may imply that the effects of eccentric loading in training are transferable to concentric strength. Our review revisits the role of eccentric loading in enhancing concentric maximal muscle strength. We also speculate on potential physiological factors (i.e., molecular and neural factors) that may differentiate the effects of eccentric and concentric resistance training on the changes in muscle strength. Currently, the majority of the studies investigating the changes in strength have been conducted using isokinetic eccentric training. This is important as there is a viewpoint that the magnitude of chronic adaptations with different modalities of eccentric exercises (i.e., isotonic, isokinetic, and isoinertial training) may also differ from each other. While it has been suggested that eccentric action has a greater transferable capacity for strength adaptations compared to concentric a…
subject: Articles
  topic: section
creator: Ryo Kataoka
creator: Yujiro Yamada
creator: William Hammert
creator: Jun Seob Song
creator: Witalo Kassiano
creator: Anna Kang
creator: Jeremy Loenneke
rights: Copyright (c) 2024 Ryo Kataoka, Yujiro Yamada, William Hammert, Jun Seob Song, Witalo Kassiano, Anna Kang, Jeremy Loenneke https://creativecommons.org/licenses/by/4.0
date: 2024-10-25
publication date: 2024-10-25
doi: 10.47206/ijsc.v4i1.328

Acute Potentiation on Propulsive-Only Jump (POJ) Performance Following Supramaximal Accentuated Eccentric Loading in High School Basketball Players
type: item
description: The purpose of this study was to investigate the acute responses of accentuated eccentric loaded (AEL) back squats to induce a post activation performance enhancement (PAPE) effect in youth athletes across three jump conditions: countermovement jump (CMJ), squat jump (SJ), and novel propulsive-only jump (POJ). Fifteen participants (age: 15.6 ± 1.1 years; RT experience: 1.3 ± 0.9 years; relative strength (back squat 1RM: body mass; 1.32 ± 0.3) completed three sessions (one familiarization, two experimental). AEL interventions were performed on each experimental session (3 sets x 3 repetitions, with only the initial repetition of each set was overloaded during the eccentric phase followed by 2 full repetitions of nonvarying loads) (ECC: 95%, 105%, 115%; CON: 60% 1RM) with pre- and post-testing (3 min, 6 min, 9 min, 12 min). Random assignment to either (a) CMJ, (b1) SJ+POJ, or (b2) POJ+SJ, where jump height (JH), net propulsive impulse (NPI) and peak relative propulsive power (PrPP) were assessed for each jump. Three 3x5 repeated measures ANOVAs were used to analyze each dependent variable across jump conditions and time with a level of significance of ρ ≤ 0.05. Results revealed a significant increase in POJ JH performance at 9 min (+12.26% ± 13.65%, p < 0.05), while CMJ and SJ performance did not show statistically differences from pre-testing. JH performances peaked at 12 min for CMJ (+2.22% ± 7.71%) and SJ (+5.03% ± 12.77%) but did not reach statistical significance. These findings suggest that male high school basketball players may realize superior or unaffected jump performances at 9-12 min post-supramaximal AEL back squats. In addition, no significant deficits in performance outcomes were found for any condition from pre- to post-testing.
subject: Articles
  topic: section
subject: Accentuated eccentric
  topic: keywords
subject: Propulsive-only jump
  topic: keywords
subject: PAPE
  topic: keywords
subject: Jump performance
  topic: keywords
subject: Sport Science
  topic: disciplines
subject: Exercise Science
  topic: disciplines
creator: John C Ditch
creator: Justin Kilian
creator: Jessica Savage
creator: Jon K Davis
rights: Copyright (c) 2025 JC Ditch, Justin Kilian, Jessica Savage, Jon K Davis https://creativecommons.org/licenses/by/4.0
date: 2025-10-10
publication date: 2025-10-10
doi: 10.47206/55n1jb25

The Validity and Reliability of the My Jump Lab Artificial Intelligence Application
type: item
description: Jump height (JH) achieved in a countermovement jump (CMJ) has been suggested to allow for the monitoring of neuromuscular fatigue (NMF) and assessment of lower body power. Although force platforms (FP) are considered the gold standard for measuring CMJ height, they are expensive compared to mobile apps such as My Jump Lab (MJL). Therefore, this study aimed to assess the concurrent validity and agreement of the MJL app compared to a FP (ForceDecks [FD]) system and to determine its test-rest reliability. A convenience sample of 26 (n = 11 females and n = 15 males) recreationally active university sport students and staff (mean ± SD; age: 23.08 ± 6.33 years; mass: 72.85 ± 9.93 kg; stature: 176.63 ± 10.18 cm) participated in the study. Participants attended the laboratory for testing on two separate occasions, separated by one week. After a standardised warm-up, they completed three CMJs on each occasion, with CMJ height simultaneously assessed by the FD and MJL app. The MJL Artificial Intelligence mode showed a mean bias of 4.32 cm [95% CI: 3.4, 5.26] overestimation with 95% limits of agreement ranging from -3.33 cm [95% CI: -4.96, -0.85] to 11.98 cm [95% CI: 10.13, 13.41]. Both methods demonstrated minimal mean bias (FD = 0.61 cm [95% CI: -0.31, 1.37] and MJL = 0.25 cm [95% CI = -0.48, 0.98]) between sessions, and both showed a similar width to their limits of agreement, ranging ~7 cm about the mean bias. In summary, the MLJ overestimated CMJ height in this sample compared to the FD system, but both methods were reliable. Given the significant differences in cost for these two methods, teams on a budget may interested in trialling the MJL app.
subject: Articles
  topic: section
subject: Countermovement jump
  topic: keywords
subject: Force decks
  topic: keywords
subject: My Jump
  topic: keywords
subject: Impulse-momentum
  topic: keywords
creator: Lee Bridgeman
creator: Bailey Cameron
creator: James Steele
rights: Copyright (c) 2025 Lee Bridgeman, Bailey Cameron, James Steele https://creativecommons.org/licenses/by/4.0
date: 2025-07-11
publication date: 2025-07-11
doi: 10.47206/ijsc.v5i1.415

Percentile Rankings and Normalization of Performance for Youth International Weightlifting Federation World Championships Competitors
type: item
description: The present study provided percentile rankings and comparisons based on sex and weight class for absolute and normalized Olympic Weightlifting (OW) performance for youth International Weightlifting Federation (IWF) World Championships competitors. Data from the IWF Youth World Championships from 2019, 2021, 2022, and 2023 were used. Allometric scaling normalized OW performance to body weight, and Sinclair scores were calculated based on IWF standards. Percentile rankings and sex and weight class differences were analyzed. In general, boys were stronger than girls for absolute and allometrically scaled OW performance, and Sinclair scores. Within boys and girls, absolute OW performance increased with weight class, while the middle weight classes tended to have superior performance than the lightest and heaviest weight classes when allometrically scaled. For the boys, Sinclair scores were greater for the middle weight classes compared to the lightest and heaviest weight classes. For the girls, there were no differences across weight class for Sinclair scores. The present study provides sex- and weight class-specific percentile rankings for absolute and normalized performance for youth OW competitors. These data may be valuable for assessing youth OW competitors and when considering appropriate weight classes for these competitors.
subject: Articles
  topic: section
subject: Youth
  topic: keywords
subject: Resistance
  topic: keywords
subject: Weight
  topic: keywords
subject: Gender
  topic: keywords
subject: Performance
  topic: keywords
subject: Weightlifting
  topic: subjects
creator: Zachary Gillen
rights: Copyright (c) 2025 Zachary Gillen https://creativecommons.org/licenses/by/4.0
date: 2025-08-15
publication date: 2025-08-15
doi: 10.47206/ijsc.v5i1.404

New Perspectives in Assessing Pickup Acceleration.
type: item
description: In team sports, linear acceleration is a fundamental skill that defines success across competitive levels. While maximal acceleration capability from a static start has been studied extensively, team sport athletes mostly accelerate from a submaximal speed. This ability to maximally accelerate from a non-static start (i.e., pickup acceleration) is largely unexplored. In this review, pickup acceleration assessment using a motorized horizontal linear position encoder (1080 Sprint) is discussed in detail, various signals explained, and a sample case study of high and low pickup capability described.
subject: Articles
  topic: section
subject: Sprinting
  topic: keywords
subject: Running
  topic: keywords
subject: Kinematics
  topic: keywords
subject: Kinetics
  topic: keywords
subject: Team Sport
  topic: keywords
subject: Team Sport athletes
  topic: subjects
subject: Track and Field
  topic: subjects
subject: Sprinting
  topic: subjects
subject: American Football
  topic: disciplines
subject: Track and Field
  topic: disciplines
creator: Mark Pryer
creator: John Cronin
creator: Chris Korfist
creator: Jono Neville
creator: Aaron Uthoff
rights: Copyright (c) 2025 Mark Pryer, Prof John Cronin, Chris Korfist, Jono Neville, Aaron Uthoff https://creativecommons.org/licenses/by/4.0
date: 2025-04-04
publication date: 2025-04-04
doi: 10.47206/ijsc.v5i1.397

The Accuracy of the Titan 1+ 10 Hz Global Positioning System for Measures of Time, Distance, and Top Speed
type: item
description: Introduction: Global Positioning System (GPS) technology provide quantifiable data concerning the number and types of movements athletes complete across training session and match player. The Titan 1+ is a novel GPS device that has not been investigated to establish measures of accuracy or reliability. The purpose of this study was to establish device accuracy for metrics including distance, top speed, and time between the Titan 1+ 10 Hz GPS device and criterion measures. Criterion measures include tape measure, stopwatch, and radar gun for measures of distance, time, and top speed, respectively. Methods and Materials: 16 male NCAA collegiate soccer players completed running protocols of varying distances and speeds, including long and short duration straight-line running (100m Run and SLR), tight and gradual change of direction running (COD T and COD G), and a team-sport simulated circuit. Results: The Titan 1+ was not significantly different from tape measured distance during the SLR protocol for 10m jog and all movements speed across 20m and 40m (p < .05). The Titan 1+ was significantly correlated to radar gun top speed measures for all distances and movement speeds during the SLR (p < .01). The Titan 1+ was significantly different from the stopwatch for measures of time accuracy (p < .0001), however significant correlations were identified for all jogging distances (p < .01), the 20m and 40m strides (p < .01), and the 10m sprint (p < .01). COD G and COD T distances were accurately measured between the Titan 1+ and tape measure (p < .05). The Titan 1+ revealed correlations for time measures during jogging and striding during the COD G (p = .001 and p < .0001) and during the COD T (p < .0001 and p< .0001). Device accuracy was established for measure of time during the TSSC (p < .05), with time measures significantly correlated between the Titan 1+ and stopwatch (p < .01). Top speed for the TSSC was significantly different between the radar gun and Titan 1+ device …
subject: Articles
  topic: section
subject: Global positioning systems
  topic: keywords
subject: GPS
  topic: keywords
subject: Titan sensor
  topic: keywords
subject: Accuracy
  topic: keywords
subject: Validity
  topic: keywords
subject: Catapult
  topic: keywords
subject: Time
  topic: keywords
subject: Distance
  topic: keywords
subject: Top speed
  topic: keywords
subject: Speed zone
  topic: keywords
creator: Victoria Elia
creator: Thomas A. Cappaert
creator: Kevin Neeld
creator: MaryCatherine Harmon
rights: Copyright (c) 2024 Victoria Elia, Thomas A. Cappaert, Kevin Neeld, MaryCatherine Harmon https://creativecommons.org/licenses/by/4.0
date: 2024-10-18
publication date: 2024-10-18
doi: 10.47206/ijsc.v4i1.326

Preparation for Powerlifting Competition: A Case Study
type: item
description: This study assessed a male competitive powerlifter over a 6-month period that encompassed his pre-contest preparation and post-contest recovery. We conducted the following monthly assessments: multi-frequency bioelectrical impedance analysis (MF-BIA), B-mode ultrasound evaluation of muscle thickness (MT), body circumferences, handgrip strength, vertical jump height, isometric lower body strength, and questionnaires for perceived mood and sleep. The athlete undertook a 3-month pre-contest preparatory period that included an extreme energy-restricted diet intended to sufficiently reduce body mass. This period also included an 8-week pre-contest training regimen with a 10-day taper intended to promote peak strength increases in the target lifts for competition. During the pre-competition period, the athlete experienced rapid and substantial losses of body mass (10.3%), body fat (6.5%) and lean mass (3.3%), the majority of which was regained in the 2-month post-competition recovery phase. The athlete's isometric knee extension strength rose sharply during the initial month of the pre-competition phase (336.4 Nm), followed by consistent declines (299 to 262.2 to 283 Nm) over the next 3 months, eventually returning close to baseline values 2 months post- competition Jump height remained steady in the 3 months in the pre-contest phase but increased (+1.4 cm) in the 2 months post-competition while handgrip strength increased during the months preceding the competition (47.5 kg to 49 kg) but decreased to 42.3 cm post-competition. Overall, the athlete did not seem to have any marked sleep disturbances. The most notable changes in mood parameters were increased tension, anger, and depression immediately preceding the competition.
subject: Articles
  topic: section
subject: Preparation
  topic: keywords
subject: Contest
  topic: keywords
subject: Competition
  topic: keywords
subject: Strength
  topic: keywords
subject: Powerlift
  topic: keywords
creator: Max Sapuppo
creator: Douglas Oberlin
creator: Ryan Burke
creator: Alec Pinero
creator: Adam Mohan
creator: Francesca Augustin
creator: Max Coleman
creator: Patroklos Korakakis
creator: Greg Nuckols
creator: Brad Schoenfeld
rights: Copyright (c) 2024 Max Sapuppo, Douglas Oberlin, Ryan Burke, Alec Pinero, Adam Mohan, Francesca Augustin, Max Coleman, Patroklos Korakakis, Greg Nuckols, Brad Schoenfeld https://creativecommons.org/licenses/by/4.0
date: 2024-12-06
publication date: 2024-12-06
doi: 10.47206/ijsc.v4i1.361

Implementing the Reverse Acute to Chronic Workload Ratio Model to Improve Movement Capacity and Roster Availability: An Example Using Data from the NFL
type: item
description: American football athletes require the development of workload capacity for repeated high-intensity efforts, and successful athletes are adept at accelerating, decelerating, and changing directions. The prescription of appropriate training volume stimulus can be difficult to determine, as there are very few guidelines for prescribing sport-specific acceleration, deceleration, and maximum velocity efforts. Preparatory training stimulus has to closely match in-game demands, but at the same time, practitioners need to avoid excessive workloads and undertraining to mitigate workload progression-related injuries and maximize roster availability. The acute-to-chronic workload ratio (ACWR) approach is based upon the fitness: fatigue ratio, which allows practitioners to monitor workloads. New technology allows for in-game positional tracking and these advancements are accessible to the public. By measuring in-game movement, coaches can quantify key metrics like the number of accelerations and average distance covered. These metrics provide a snapshot of in-game demands and performance requirements. Using a reverse engineering approach, coaches can utilize ACWRs to calculate predefined targets to ensure athletes are adequately prepared for gameplay. Here we use the ACWR concept and previously reported in-game data derived from the National Football League to show how to reverse engineer the targeted number of efforts and distances to assist in preparatory pre-season training program design. This approach, which we term the Reverse ACWR Method, can be used to set guidelines for training volumes and workload progressions and provides a systematic, quantitative approach that complements periodization. As such, the Reverse ACWR Method allows practitioners to calculate target sport-specific workloads and training progressions derived from scientific-grounded methodology, which may enhance performance, readiness, and roster availability. Although this paper presents an example of …
subject: Articles
  topic: section
subject: Workload progression
  topic: keywords
subject: Peak athletic performance
  topic: keywords
subject: Readiness
  topic: keywords
subject: Injury
  topic: keywords
subject: American football
  topic: keywords
subject: Fitness fatigue model
  topic: keywords
subject: Strength and Conditioning
  topic: disciplines
subject: Sports Science
  topic: disciplines
creator: Trevor Short
creator: Paulette M Yamada
rights: Copyright (c) 2025 Trevor Short, Paulette M Yamada https://creativecommons.org/licenses/by/4.0
date: 2025-01-10
publication date: 2025-01-10
doi: 10.47206/hmrmy739

The Reliability and Validity of Different Methods for Measuring Countermovement Jump Height
type: item
description: Previous research indicates the importance of the countermovement jump (CMJ) test to monitor lower-limb power and neuromuscular fatigue. While jump height (JH) can be measured using various equipment, this study compared the JH obtained from the Just Jump System (JJS), OptoJump and the MyJump2 app against the Vald ForceDecks system using the impulse-momentum calculation method, which is regarded as the gold standard method to calculate JH. This study also assessed the one-week test-retest reliability of these pieces of equipment. The participants in this study were 20 (n = 12 male and n = 8 female) university sports students and staff (mean ± SD; age: 20.90 ± 2.63 years; stature: 1.76 ± 0.10 m; mass: 72.17 ± 11.07 kg). Participants completed a standardised warm-up and rested for three minutes before completing three CMJs on each piece of equipment in a randomised, counterbalanced order. The same protocols were used in the second session, with a different equipment testing order. Both MyJump and OptoJump have high agreement levels (Mean bias and 95% CI = 2.32 cm [1.57 – 3.09] and 1.92 cm [1.23 – 2.59], respectively) with the gold measurement standard (ForceDecks using IM). However, a high mean bias for the JJS (Mean bias = 9.88 cm [9.26 – 10.46]) was reported. This study also found that all methods are reliable for assessing JH (Mean bias and [95% CI]: ForceDecks = 0.24 cm [-0.47 – 0.92], JJS = 0.74 cm [0.08 -1.42], MyJump = 0.05 cm [-0.57 – 0.71] and Optojump = -0.14 cm [-0.77-0.49]). Overall, the equipment investigated in this study showed high levels of reliability, and only the JJS had low validity compared to the ForceDecks. Coaches should consider what data they want to collect, its validity and reliability, the purpose of the testing and the cost of the equipment when deciding which system to purchase.
subject: Articles
  topic: section
subject: Jumping
  topic: keywords
subject: ForceDecks
  topic: keywords
subject: OptoJump
  topic: keywords
subject: Just jump system
  topic: keywords
subject: MyJump
  topic: keywords
creator: Bailey Cameron
creator: James Steele
creator: Lee Bridgeman
rights: Copyright (c) 2025 Bailey Cameron, James Steele, Lee Bridgeman https://creativecommons.org/licenses/by/4.0
date: 2025-06-13
publication date: 2025-06-13
doi: 10.47206/ijsc.v5i1.406

Maturation and Physical Performance in National Level Youth Basketballers: Implications for Strength and Conditioning Coaches
type: item
description: The purpose of this study was to (i) describe the anthropometric and performance characteristics of New Zealand national level youth basketballers and (ii) examine the relationship between maturation and these characteristics. One hundred and eighty-nine Under 14 and U15 basketball players, boys (n=100; age=14.1±0.5 years; height=178.3±9.0 cm; body mass=70.0±16.0 kg) and girls (n=89; age=14.1±0.7 years; height=169.8±7.6 cm; body mass=65.2±12.3 kg) participated in the study. Anthropometric variables were measured to determine maturity timing and status. Horizonal and vertical jumps, change of direction agility and speed were assessed for physical performance. Differences in performance tests between the boys and girls were assessed via independent samples T-test and linear regression analyses were performed to assess if %PAH (predictor) was associated with each anthropometric or performance variable (outcome). There were significant differences between boys and girls for all anthropometric and performance tests favouring boys (ES = 0.33 to 1.47; p < 0.001). Girls were significantly more mature (greater %PAH) than boys (ES = 1.85; p <0.05). In boys, for every 1% increase in %PAH there was a moderate (ES = 0.63 to 0.71) increase in anthropometric measures and mostly small (ES = 0.24 to 0.33) increases in performance measures. In girls, the increase in anthropometric measures was moderate to large (ES = 0.59 to 0.82). These findings demonstrate that maturation was significantly associated with anthropometric and performance variables in boys but only anthropometric variables in girls. Strength and conditioning coaches should be aware of these differences and consider the practical implications that maturation can have in long-term athlete development planning of young basketball players.
subject: Articles
  topic: section
subject: Growth
  topic: keywords
subject: Development
  topic: keywords
subject: Testing
  topic: keywords
subject: Performance standards
  topic: keywords
subject: Anthropometry
  topic: keywords
subject: LTAD
  topic: keywords
creator: Jaron Kung
creator: Chris Whatman
creator: Michael McGuigan
creator: Craig Harrison
creator: Stephen Bird
rights: Copyright (c) 2025 Jaron Kung, Chris Whatman, Michael McGuigan, Craig Harrison, Stephen Bird https://creativecommons.org/licenses/by/4.0
date: 2025-03-07
publication date: 2025-03-07
doi: 10.47206/ijsc.v5i1.389