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Brady, CJ, Harrison, AJ, Flanagan, EP, Haff, GG, and Comyns, TM. The relationship between the isometric squat and stretch shortening cycle function and sprint acceleration performance in hurling players. J Strength Cond Res38(6): e288–e298, 2024—The primary aim was to examine the relationship between sprint acceleration performance and the performance tests: isometric squat (ISqT), countermovement jump (CMJ), and reactive strength index (RSI). The secondary aim determined whether these tests could distinguish between sprint performance levels. Twenty-six male under-21 subjects completed the ISqT, with peak force (PF), relative PF, force at 100, 150, and 200 milliseconds (ms), and impulse (0–200 ms) measured. Jump height (JH) was calculated from the CMJ and RSI during the 10-5 repeated jump test. Subjects completed 3 × 30-m sprints with splits taken at 5, 10, 20, and 30 m. Pearson’s product moment correlations were used to assess the relationships between measures, and independent samples ttests were used to determine whether differences existed in sprint ability of those in the top and bottom quartiles for force at 100 ms, CMJ, and RSI. Significant negative moderate correlations were reported between force at 100 ms and 0–5 m and 5–10 m, significant moderate and large negative correlations between CMJ and all splits and significant large correlations between RSI and splits over 5 m. Force at 100 ms distinguished between performance levels from 0 to 5 m, CMJ from 10 to 20 m, and RSI from 20 to 30 m; faster subjects produced significantly higher force, JHs, and RSI scores. Three principal components explaining 86.1% of the variation in the data set were identified: sprint times and stretch shortening cycle capabilities (33.3%), time-specific force (29.9%), and absolute and relative strength (22.8%).

Xu, J, Turner, A, Comyns, TM, Chavda, S, and Bishop, C. The countermovement rebound jump: Between-session reliability and a comparison with the countermovement and drop jump tests. J Strength Cond Res38(4): e150–e159, 2024—The countermovement jump (CMJ) and drop jump (DJ) are widely used jump tests to evaluate an athlete's neuromuscular performance. Nevertheless, conducting both the CMJ and the DJ assessments during one testing session can demand a considerable time investment that practitioners or coaches might not always have available. This study investigated whether the countermovement rebound jump (CMRJ) could be considered a viable alternative to the CMJ and DJ tests, respectively. Thirty-three physically active students volunteered as subjects (age: 27.2 ± 5.9 years, height: 1.78 ± 0.8 cm, body mass: 77.5 ± 11.5 kg), with 18 jumps completed for each subject across 2 testing sessions. The jump height (JH) and strategy-based metrics (time to take-off [TTTO], countermovement depth [CM depth], and reactive strength index [RSI] modified for CMJ and the first jump of the CMRJ; leg stiffness [Kleg], ground contact time [GCT], and RSI for DJ and the second jump for the CMRJ) were calculated simultaneously via the impulse-momentum, flight time, double integration, and motion capture methods. All variables were examined by repeated-measures analysis of variance, 2-way random effects model intraclass correlation coefficient (ICC), coefficient of variation (CV), and standard error of measurement, with the significance set at p≤ 0.05. All 3 jump tests showed good-to-excellent relative reliability (ICC = 0.79–0.98) and good-to-moderate CV (≤9.83), with the only exception being Klegmeasured during the DJ and in the second jump of the CMRJ assessment (CV ≤ 16.01%). Of all measured metrics, significant differences were only observed regarding TTTO between jumps (p≤ 0.027, effect size [ES] ≤ 0.49). The comparison of calculation methods indicated that the JH calculated by 4 methods were not significantly different between jump actions (p≥ 0.254). These findings support the use of the CMRJ as a reliable alternative to the CMJ and DJ tests. However, practitioners should be mindful of using Klegas a metric, whereas practitioners are also advised to allocate sufficient familiarization trials before implementing the CMRJ into their routine test batteries.

Comyns, TM, Murphy, J, and O’Leary, D. Reliability, usefulness, and validity of field-based vertical jump measuring devices. J Strength Cond Res37(8): 1594–1599, 2023—The purpose of this study was to examine the test-retest reliability, usefulness, and validity of field-based devices, in determining jump height (JH) during a countermovement jump (CMJ). Twenty-one male (22.8 ± 2.4 years; 1.82 ± 0.07 m; 86.0 ± 10.4 kg) and 7 female field sport athletes (20.5 ± 1.5 years; 1.65 ± 0.06 m; 65.4 ± 7.2 kg) performed 3 CMJs with data simultaneously recorded using a force plate (criterion measure), Optojump, Output Capture, and Push-Band 2.0. Reliability was determined by intraclass correlation (ICC) and coefficient of variation (CV) analyses. Usefulness was assessed by comparing typical error (TE) with the smallest worthwhile change (SWC), and the validity analyses involved repeated measures analysis of variance with post hoc analysis, Pearson correlation coefficient (r), coefficient of determination, and Bland-Altman 95% limits of agreement analyses. All 3 field-based devices were deemed reliable in assessing CMJ height as the respective ICCs ≥ 0.80 and the CV ≤ 10%. Only the Optojump and Output Capture devices were rated as “good” at detecting the SWC in performance (Optojump SWC: 1.44 > TE: 1.04; Output Capture SWC: 1.47 > TE: 1.05). The Output Capture device demonstrated acceptable validity for CMJ height assessment, whereas the Push-Band 2.0 showed systematic bias when compared with the criterion force plate data. Systematic difference was also evident for the Optojump potentially due to the optical switching-cell position on the Optojump. Although all 3 devices showed excellent reliability, the Optojump and Output Capture devices offer practitioners a cost effective, reliable, and valid method of assessing the smallest worthwhile change in CMJ performance in an applied setting.

Rossiter, A, Warrington, GD, and Comyns, TM. Effects of long-haul travel on recovery and performance in elite athletes: a systematic review. J Strength Cond Res36(11): 3234–3245, 2022—Elite athletes are often required to travel long-haul (LH) across numerous time zones for training or competition. However, the extent to which LH travel affects elite athlete performance remains largely unknown. The purpose of this systematic literature review was to critically evaluate available evidence on the effects of LH travel on elite athlete psychometric, physiological, sleep, and performance markers. Electronic database searches of PubMed, SPORTDiscus, Scopus, and Web of Science were conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies were eligible for inclusion if subjects were identified as elite athletes who embarked on a LH flight (>6 hours) and used an outcome measurement of recovery or performance after the flight. Studies that were retrospective, used light therapy or pharmacological interventions were not included. Of 2,719 records assessed, 14 studies comprising a total of 197 athletes from 6 sports met the inclusion criteria. There was an increase in perceived jet lag and disturbance to various physiological markers after LH travel; however, there was minimal disturbance in other psychometric markers. Sleep was not negatively affected by LH travel. Of 10 studies that assessed performance, 3 found decrements in indirect markers of performance. Elite athletes perceived themselves to be jet lagged and experienced disturbance to various physiological mechanisms after LH travel; however, the effect on performance was inconclusive. Future research would benefit from higher quality studies with improved control measures, larger sample sizes from a wider variety of sports, and use of ecologically valid measures of circadian rhythm and athletic performance.

Freitas, TT, Pereira, LA, Alcaraz, PE, Comyns, TM, Azevedo, PHSM, and Loturco, I. Change-of-direction ability, linear sprint speed, and sprint momentum in elite female athletes: differences between three different team sports. J Strength Cond Res36(1): 262–267, 2022—The aim of this study was to compare the performance of elite female players from 3 different sports in linear sprint and change-of-direction (COD) tests and examine their efficiency for changing direction through the calculation of the COD deficit (i.e., the difference in velocity between a linear sprint and a COD task of equal distance). One hundred fifty-four elite players (rugby, n= 40, national team members; soccer, n= 57 and handball n= 57, first division players from the respective Brazilian National Championships) were assessed in the 20-m linear sprint and Zigzag COD tests. A one-way analysis of variance with a Tukey post hoc was used to detect between-sport differences. Female rugby sevens players achieved faster sprint velocities than handball (20‐m: 6.21 ± 0.24 m·s−1; 6.07 ± 0.27 m·s−1, respectively; p< 0.05) and soccer players (5‐m: 4.71 ± 0.26 m·s−1vs. 4.51 ± 0.20 m·s−1; and 20‐m: 6.08 ± 0.19 m·s−1; p< 0.05) and exhibited the greatest COD deficits (2.95 ± 0.25 m·s−1; 2.69 ± 0.19 m·s−1; 2.82 ± 0.17 m·s−1, for rugby, handball, and soccer, respectively; p< 0.05). Handball players outperformed all other athletes in the Zigzag test (3.38 ± 0.15 m·s−1; 3.26 ± 0.10 m·s−1; 3.26 ± 0.10 m·s−1, for handball, rugby, and soccer, respectively; p< 0.05) but presented the lowest COD deficits (p< 0.05). Furthermore, soccer players displayed inferior sprint momentum when compared with the other sports (p< 0.05). Linear sprint and COD ability differ significantly among elite female athletes from different team sports, with handball players exhibiting a greater COD speed and efficiency to change direction, with respect to their maximum sprint velocity. The between-sport differences observed suggests that specific training and game demands may affect both sprint and COD performance.

Supplemental Digital Content is Available in the Text.Rebound jumping is one of the most commonly used movement patterns to assess and monitor fast stretch-shortening cycle (SSC) mechanics, a critical component for rapid movements like sprinting, jumping, and directional changes. This narrative review explores the mechanical and neuromuscular mechanics underlying fast SSC function and critically evaluates the strengths and weaknesses of commonly used testing protocols, including drop jumps and multiple rebound jump tests, along with commonly reported metrics from these tests. By integrating scientific evidence with practical applications, the aim of this review is to guide practitioners in selecting appropriate assessment tools and implementing evidence-based strategies to evaluate fast SSC performance in athletes.

THIS ARTICLE EXAMINES THE APPLICATION OF A VARIETY OF MODALITIES TO ELICIT A POSTACTIVATION POTENTIATION (PAP) RESPONSE IN SPRINTING. WE PRESENT THE EXISTING LITERATURE ON THE ACUTE EFFECTS OF BACK SQUATS, POWER CLEANS, PLYOMETRICS, AND SLED PULLING ON SPRINT DISTANCES RANGING FROM 5 TO 50 M. WE ALSO DISCUSS AND PROVIDE AN EXAMPLE OF HOW COACHES CAN ASSESS THE INDIVIDUAL EFFECTS OF PAP PROTOCOLS ON THEIR ATHLETES TO IDENTIFY WHETHER A PROTOCOL ELICITS AN ACUTE IMPROVEMENT OR IMPAIRMENT IN PERFORMANCE. FINALLY, WE PROVIDE PRACTICAL RECOMMENDATIONS ON HOW COACHES CAN INCORPORATE THESE METHODS INTO A SPRINT TRAINING SESSION.

THIS ARTICLE REVIEWS RESEARCH RELATING TO THE STRETCH-SHORTENING CYCLE AND PLYOMETRICS. THE ARTICLE INSTRUCTS STRENGTH AND CONDITIONING PRACTITIONERS IN THE USE OF GROUND CONTACT TIMES AND THE REACTIVE STRENGTH INDEX IN PLYOMETRIC TRAINING. DOCUMENTATION ON HOW THESE MEASUREMENTS CAN BE USED TO OPTIMIZE PLYOMETRICS AND TO IMPROVE ATHLETES' FAST STRETCH SHORTENING CYCLE PERFORMANCE IS PROVIDED. RECOMMENDATIONS ARE MADE REGARDING THE USE OF GROUND CONTACT TIMES TO IMPROVE TRAINING SPECIFICITY AND THE USE OF THE REACTIVE STRENGTH INDEX TO OPTIMIZE PLYOMETRICS, TO MONITOR TRAINING PROGRESS, AND TO SERVE AS A MOTIVATIONAL TOOL. A 4-STEP PROGRESSION OF IMPLEMENTATION IS DETAILED.

Background: Concern has been raised over the injury risk to school Rugby union (Rugby) players and the potential long-term health consequences. Despite the increase in studies for this cohort, the influence of playing position on injury incidence and presentation is unclear.Purpose: To describe the incidence, nature and severity of match injuries for school Rugby in Ireland overall, and as a function of playing position.Study Design: Prospective cohort study.Methods: Data were collected from 15 male (aged 16-19 years) school Senior Cup teams across 2 seasons. In total, 339 players participated in season 1, whereas 326 players participated in season 2. Injury data were recorded onto a bespoke online platform. Match exposure was also recorded.Results: The incidence rate of match injuries (24-hour time loss) was 53.6 per 1000 hours. Across both seasons, 6810 days were lost from play due to injury. Forwards (65.4 per 1000 hours) sustained significantly more (P< 0.05) injuries than backs (40.5 per 1000 hours). The head, shoulder, knee, and ankle were the most common injured body regions; however, forwards sustained significantly more (P< 0.05) head and shoulder injuries than backs. The tackle was responsible for the majority of injuries in both groups. The highest proportion of injuries occurred during the third quarter.Conclusion: Clear differences in injury presentation and incidence were evident when comparing forwards versus backs. The high rate of head and shoulder injuries in the forwards suggest the need for more targeted injury-prevention strategies and further research on education and laws around the tackle event. The spike of injuries in the third quarter suggests that fatigue or inadequate half-time warm-up may be a contributing factor warranting further exploration.Clinical Relevance: This study demonstrates clear differences in injury presentation according to playing position in school Rugby and highlights the need for a more tailored approach to the design and implementation of injury-prevention strategies.Level of Evidence: Level 3

Background: Rugby union is a physically demanding sport that carries an inherent risk of injury. Despite being a popular and widely played team sport, little is known about injuries occurring across the male and female amateur game.Purpose: To establish and compare injury incidence, nature, and severity in male and female Irish amateur rugby union.Study Design: Prospective cohort study.Level of Evidence: Level 3.Methods: Data were collected prospectively from 25 male teams (959 players) and 8 female teams (234 players) over 2 full seasons. Both time-loss (24-hour time-loss injury definition) and non-time-loss match injury reports were collected, alongside match exposure data.Results: Time-loss match injury incidence rates were 49.1/1000 and 35.6/1000 player-hours for male and female players, respectively. Concussion and ankle ligament sprains were the most common diagnoses for male (5.6/1000 and 4.4/1000 player-hours, respectively) and female players (5.5/1000 and 3.9/1000 player-hours, respectively). Anterior cruciate ligament injuries presented the highest injury burden for male and female players with 200.3 and 307.2 days of absence per 1000 player-hours, respectively. In female players, 83% of noncontact injuries occurred in the fourth quarter of match play.Conclusion: While female players had a lower overall injury incidence rate compared with male players, concussion and ankle ligament injuries were the most common injuries in both cohorts. In female players, a high rate of noncontact injuries in the second half points to the need for strength and conditioning training programs to reduce fatigue-related injuries.Clinical Relevance: Establishing the incidence and burden of rugby-related injuries is an essential step in minimizing injury risk. This epidemiological information will aid the development of future reduction strategies, including education and coaching strategies and strength and conditioning programs, informed by the most common injuries observed and the mechanism of injury.