Journal of Strength and Conditioning Research最新文献

{"title":"Biceps Femoris EMG Activity During Incline Treadmill Running and Nordic Hamstring Task.","authors":"Turan A Akyürek, Hayri Ertan, Abdulkerim Darendeli","doi":"10.1519/JSC.0000000000005049","DOIUrl":"10.1519/JSC.0000000000005049","url":null,"abstract":"<p><strong>Abstract: </strong>Akyürek, TA, Ertan, H, and Darendeli, A. Biceps femoris EMG activity during incline treadmill running and nordic hamstring task. J Strength Cond Res 39(5): 540-546, 2025-Although the Nordic hamstring exercise (NHE) is an effective method for strengthening the knee flexors, untrained individuals or intermediate level athletes may have difficulty performing it. In this study, we propose incline treadmill running as an alternative knee flexor exercise. The aim of this study was to compare the biceps femoris (BF) muscle activity (electromyography, EMG) levels between NHE and 10% grade treadmill running at 3 speeds. Nineteen recreationally active men were recruited for the study. Maximum voluntary contraction (MVC) with the knee flexors were completed. Nordic hamstring exercise and 10% grade treadmill running tasks were performed in a randomized counterbalanced order. Biceps femoris EMG activity was recorded during the measurements. Statistical significance was set to p < 0.05. We found that the peak EMG amplitude for BF was higher during the NHE (∼63% MVC) than during treadmill running at a 10% grade across low-to-moderate speeds. Increasing the running speed from 3.61 m·s -1 to 4.16 m·s -1 (∼49% MVC) raised the peak EMG amplitude by approximately 10% MVC. In addition, the variability in EMG amplitude for BF was greater during 10% grade treadmill running than during NHE. Although the peak EMG activity was greater during the NH task, it reached comparable levels when performing 10% grade treadmill running at a moderate running speed. Our results suggest that incline treadmill running can be an alternative knee flexor exercise that can be individualized by adjusting treadmill grade and speed, particularly for untrained individuals.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"540-546"},"PeriodicalIF":2.5,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143605297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantifying Added Drag in Swimming With Parachutes: Implications for Resisted Swimming Training.","authors":"Vittorio Coloretti, Silvia Fantozzi, Giorgio Gatta, Marco Bonifazi, Paola Zamparo, Matteo Cortesi","doi":"10.1519/JSC.0000000000005109","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005109","url":null,"abstract":"<p><strong>Abstract: </strong>Coloretti, V, Fantozzi, S, Gatta, G, Bonifazi, M, Zamparo, P, and Cortesi, M. Quantifying added drag in swimming with parachutes: implications for resisted swimming training. J Strength Cond Res 39(5): e701-e705, 2025-Swimming parachutes are often used during training as resistive equipment, but their added load and the hydrodynamic effects of the swimmer in front have yet to be investigated. This study explores the drag coefficient (k) of 4 commercial parachutes with different sizes under 3 conditions: (a) when towed without a swimmer in front (kpara), (b) pulled by a passive (streamlined) swimmer (kPpara), and (c) pulled by an actively propelling swimmer (kApara). An electromechanical device was used to assess kpara and kPpara as the ratio between towing force and the square of towing velocity during 5 trials at different velocities while kApara was measured based on full-tethered and semi-tethered forces using the residual thrust methods. The values of kpara were as follows: 15.4 ± 0.1, 19.7 ± 0.1, 37.2 ± 0.1, and 73.9 ± 2.8 N·s2·m-2 for parachutes with surfaces of 400, 529, 900, and 1,600 cm2, respectively. Parachute resistance decreased by approximately 21% when pulled by a passive swimmer, whereas it increased by about 15% when pulled by a propelling swimmer. Possible explanations for these differences include drafting and added mass effects. Data reported in this study can assist coaches in quantifying the added load of swimming parachutes during training, by knowing only the parachute size and the swimming velocity.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":"39 5","pages":"e701-e705"},"PeriodicalIF":2.5,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143970747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Physical Working Capacity at Pain Intensity Threshold in Females.","authors":"Danielle A Sterner, Jeffrey R Stout, Brandi B Antonio, Abigail W Anderson, Ethan C Hill, David H Fukuda","doi":"10.1519/JSC.0000000000005059","DOIUrl":"10.1519/JSC.0000000000005059","url":null,"abstract":"","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"e628-e633"},"PeriodicalIF":2.5,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143605313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of Dynamic Strength Index Based on Free-Weight Exercises for Collegiate Male Sprinters.","authors":"Kentaro Chino, Hayate Tokuoka, Yoshihiko Ito","doi":"10.1519/JSC.0000000000005048","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005048","url":null,"abstract":"<p><strong>Abstract: </strong>Chino, K, Tokuoka, H, and Ito, Y. Development of dynamic strength index based on free-weight exercises for collegiate male sprinters. J Strength Cond Res 39(5): e639-e646, 2025-The dynamic strength index (DSI) serves as a predictive measure of dynamic performance qualities, calculated as the ratio of peak force during the countermovement jump (CMJ-PF) to that during the isometric midthigh pull (IMTP-PF). This study aimed to develop a method for determining the DSI using free weights instead of a force plate for collegiate male sprinters. Thirteen collegiate male sprinters (age, 20.0 ± 0.8 years) underwent measurements of CMJ-PF and IMTP-PF using a force plate. In addition, 1 repetition maximum (1RM) of the back squat, deadlift (DL), and trap-bar deadlift was measured as alternative indicators of IMTP-PF. As alternative indicators of CMJ-PF, the 1RM of the hang clean, barbell squat jump (SJ-1RM), and trap-bar squat jump was measured. Among the alternative IMTP-PF indicators, DL-1RM exhibited the strongest correlation with IMTP-PF (r = 0.52). Among the alternative CMJ-PF indicators, SJ-1RM showed the strongest correlation with CMJ-PF (r = 0.69). Furthermore, the alternative DSI calculated as the ratio of SJ-1RM to DL-1RM demonstrated the strongest correlation with the DSI (r = 0.56) among the alternative DSIs. Corresponding to a \"very high\" DSI (>0.80) and a \"low\" DSI (<0.60), the alternative DSI values calculated as the SJ-1RM to DL-1RM ratio were 0.30 and 0.43, respectively. Using the alternative DSI, derived from the SJ-1RM to DL-1RM ratio, coaches and practitioners can assess the dynamic performance qualities of collegiate male sprinters using free weights instead of a force plate.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":"39 5","pages":"e639-e646"},"PeriodicalIF":2.5,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144001225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Changes in Physical Training and Injury Incidence Following the Introduction of a New Military Fitness Test.","authors":"Regis C Pearson, Tyson Grier, Timothy Benedict, Olivia Mahlmann, Michelle Canham-Chervak","doi":"10.1519/JSC.0000000000005063","DOIUrl":"10.1519/JSC.0000000000005063","url":null,"abstract":"<p><strong>Abstract: </strong>Pearson, RC, Grier, T, Benedict, T, Mahlmann, O, and Canham-Chervak, M. Changes in physical training and injury incidence following the introduction of a new military fitness test. J Strength Cond Res 39(5): e684-e691, 2025-Physical training (PT) and injury incidence may be affected by the implementation of a new physical fitness test. Current investigation measured changes in PT and injury incidence following field testing of the Army Combat Fitness Test (ACFT). Sixty-one battalions were administered electronic surveys before and after ACFT field testing from October 2018 through June 2020. Surveys collected demographics, injury incidence, and PT within the previous 12 months. Army Combat Fitness Test records were obtained from the Digital Training Management System. Statistical significance was accepted at p ≤ 0.05. One thousand one hundred thirty-four soldiers completed both surveys. Male soldiers represented 77% (31.3 ± 8.6 years, 21.3 ± 4.3 kg·m -2 ) and female soldiers represented 23% (30.0 ± 7.8 years, 24.1 ± 3.1 kg·m -2 ) of respondents. Male soldiers reported lower unit calisthenics training, higher unit resistance training, and higher unit total exercise following field testing (minutes per week, p < 0.05). Male soldiers reported higher personal running, higher personal resistance training, lower personal obstacle course training, and lower personal total exercise after field testing (minutes per week, p < 0.05). Female soldiers reported lower unit running, higher unit resistance training, higher personal resistance training, lower personal obstacle course training, and lower personal total exercise after field testing (minutes per week, p < 0.05). After field testing, male soldiers reported a greater number of lower back injuries (+2.9%, p = 0.01) and a greater number of resistance training injuries (+1.7%, p < 0.01). Changes in specific training modalities may lead to changes in activities associated with injury. Proper technique, periodization, individualization, and recovery education are recommended to control injury incidence when a new PT program is implemented.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"e684-e691"},"PeriodicalIF":2.5,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143605356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Influence of Maturity Status on the Development of Neuromuscular Performance in the Lower Body After One Season in Adolescent Tennis Players.","authors":"Ernest Baiget, Jose Canós-Portalés, Rafael Martínez-Gallego, Francisco Corbi, Jaime Fernandez-Fernandez","doi":"10.1519/JSC.0000000000005044","DOIUrl":"10.1519/JSC.0000000000005044","url":null,"abstract":"<p><strong>Abstract: </strong>Baiget, E, Canós-Portalés, J, Martínez-Gallego, R, Corbi, F, and Fernandez-Fernandez, J. The influence of maturity status on the development of neuromuscular performance in the lower body after 1 season in adolescent tennis players. J Strength Cond Res 39(5): 593-601, 2025-The purpose of the study was to determine the effects of biologic maturation on lower body neuromuscular performance over the course of a competitive tennis season in young tennis players. Eighty junior male and female tennis players were divided into Pre-Peak Height Velocity (PHV) ( n = 36), Circa-PHV ( n = 25), and Post-PHV ( n = 19). Players were tested in 2 occasions, separated by 12 months, including speed (5, 10, and 20 m linear sprint), change of direction (CoD), and bilateral/unilateral countermovement jump (CMJ). Group-by-time interactions were found in biometric and maturational parameters ( p = 0.031 to <0.001). All maturational groups increased their height and body mass (BM) ( p < 0.01 to 0.001), while only Circa- and Post-PHV groups increased their BM index ( p < 0.001 and 0.007). Within-group improvements from pre-to post-test were found in bilateral ( p = 0.002 to 0.006) and dominant unilateral ( p < 0.001 to 0.032) CMJ in all groups, while 10-m ( p = 0.027) linear sprint and dominant and nondominant CoD only improved in the Post-PHV group ( p = 0.03 to 0.008). No group-by-time interactions were found in any neuromuscular measure. In conclusion, maturation status did not significantly affect the neuromuscular performance improvement over a season in neuromuscular parameters of adolescent tennis players, suggesting that it is not only important to establish the maturation stage when working with these athletes, but also the need of including specific training based on biologic maturation status.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"593-601"},"PeriodicalIF":2.5,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143605318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shoulder Internal and External Rotation Strength Assessment in Baseball Pitchers: Normative Data and Reliability.","authors":"Trey D W Job, Matthew R Cross, John B Cronin","doi":"10.1519/JSC.0000000000005072","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005072","url":null,"abstract":"<p><strong>Abstract: </strong>Job, TDW, Cross, MR, and Cronina, JB. Shoulder internal and external rotation strength assessment in baseball pitchers: normative data and reliability. J Strength Cond Res 39(5): e634-e638, 2025-Rotator cuff strength assessments are valuable for monitoring throwing athlete injury and performance status. Portable technology enables \"in-field\" assessment and, therefore, increases utility. The purpose of this study was to quantify the reliability of strain gauge technology for measuring shoulder rotator strength and provide normative strength values for high school and college pitchers. Subjects (n = 15) participated in 3 testing sessions consisting of 5 maximal isometric shoulder internal rotation (IR) and 5 external rotation trials separated by 7 days. Variables of interest included peak force (Fmax), peak torque (Tmax), rate of force development, and rate of torque development. Coefficients of variation ranged from 4.3 to 5.8% for peak values and 16.0-28.5% for rate measures. Intraclass correlation coefficient estimates ranged from 0.79 to 0.89 for peak values, and 0.80-0.91 for rate measures, with IR typically marginally better than ER. Although practitioners need to be mindful of managing error (e.g., through familiarity), peak measures of rotator cuff strength assessed using portable strain gauge are promising for simple field-based monitoring of shoulder health for throwing athletes.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":"39 5","pages":"e634-e638"},"PeriodicalIF":2.5,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143970941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biomechanical Insights Into Rotary Inertial Devices vs. Traditional Resistance Training in Half-Squats: A Comparative Analysis of Force, Velocity, and Displacement.","authors":"Carlos Galiano, Francisco Javier Nuñez, Stuart McErlain-Naylor, Pablo Floria","doi":"10.1519/JSC.0000000000005073","DOIUrl":"10.1519/JSC.0000000000005073","url":null,"abstract":"<p><strong>Abstract: </strong>Galiano, C, Nuñez, FJ, McErlain-Naylor, S, and Floria, P. Biomechanical insights into rotary inertial devices vs. traditional resistance training in half-squats: a comparative analysis of force, velocity, and displacement. J Strength Cond Res 39(5): 531-539, 2025-Although rotary inertial devices (RIDs) have been used in resistance training for many years, there is still limited knowledge of the specific biomechanics that distinguish them from traditional resistance training (TRT) methods. The aim of this study is to compare the serial data of force, velocity, and displacement over time in half-squats performed with both devices when the intensity is based on the concentric mean propulsive velocity (MPV). A total of 20 experienced subjects completed 3 sets of 6 half-squats using both RID and TRT. To ensure a similar load intensity, the concentric phase was matched according to the MPV. Measurements of vertical ground reaction force (vGRF), velocity, and displacement were taken for each repetition of the half-squat. The results showed that TRT exhibited a higher vGRF than RID during 0-57% of the concentric phase but a lower vGRF during 74-93% ( p < 0.001). Eccentric vGRF was also higher for TRT throughout much of the eccentric phase (0-13%, 38-54%, and 68-100%, p < 0.001). Rotary inertial device demonstrated faster vertical velocity than TRT during 31-52% of the concentric phase and 1-40% of the eccentric phase ( p < 0.001). However, during the latter part of the concentric phase (72-99%), TRT exhibited faster vertical velocity compared with RID. In addition, TRT resulted in a higher vertical position than RID at the end (67-100%) of the concentric phase ( p = 0.036). Coaches should be aware of these biomechanical differences when prescribing resistance training with RID or TRT, as even with similar loads, distinct patterns in vGRF and velocity over time can lead to different effects on the athlete.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"531-539"},"PeriodicalIF":2.5,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143605298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Acute Effects of Assisted and Resisted Sprint Training on Subsequent Sprint Performance: A Systematic Review and Meta-Analysis.","authors":"Kai Xu, MingYue Yin, YuMing Zhong, KongYun Huang, YiMeng Xu, Jing Zhou, Ran Wang","doi":"10.1519/JSC.0000000000005087","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005087","url":null,"abstract":"<p><strong>Abstract: </strong>Xu, K, Yin, M, Zhong, Y, Huang, K, Xu, Y, Zhou, J, and Wang, R. Acute effects of assisted and resisted sprint training on subsequent sprint performance: A systematic review and meta-analysis. J Strength Cond Res 39(5): e711-e720, 2025-The aim of the meta-analysis was to determine the acute effects of resisted (RST), assisted (AST), and unresisted (UST) sprint training on sprint performance and to identify the optimal training protocol. A computerized search was conducted in 5 databases, resulting in the inclusion of 23 studies and 395 subjects. The findings indicated that RST acutely improved sprint performance (effect size [ES] -0.20; p < 0.05), while UST (ES = -0.03) and AST (ES = -0.18) did not produce significant improvements (p > 0.05). Subgroup analyses revealed that RST load as a percentage of body mass (%BM) showed the greatest improvement with heavy loads (50-75% BM, ES = -0.40) compared with light (0-19% BM, ES = -0.22), moderate (20-49% BM, ES = -0.21), and very heavy (>75% BM, ES = 0.10) loads. Further analyses indicated that sled pushing (ES = -0.60) was more effective than sled pulling (ES = -0.34) under heavy load RST conditions. Nonlinear meta-regression results demonstrated that sprint performance improvement exhibited an inverted-U relationship with RST load. In addition, heavy load RST and moderate load AST did not disrupt subsequent sprinting technique. In conclusion, only RST acutely improved subsequent sprint performance, whereas AST and UST did not. For optimal results with RST, it is recommended to use 1 set of heavy loads (50-75% BM) for sled pushing for a distance of 15-20 meters, followed by a rest period of 4-8 minutes before performing 0-30 meters of UST.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":"39 5","pages":"e711-e720"},"PeriodicalIF":2.5,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143970905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Effects of Repeated-Sprint Training vs. Short-Bout High-Intensity Interval Training on Hamstring Architecture and Physical Fitness.","authors":"Fraser Thurlow, Ryan Timmins, Shaun J McLaren, Bradley Lawton, Nicholas Cowley, Andrew Townshend, Jonathon Weakley","doi":"10.1519/JSC.0000000000005064","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005064","url":null,"abstract":"<p><strong>Abstract: </strong>Thurlow, F, Timmins, R, McLaren, SJ, Lawton, B, Cowley, N, Townshend, A, and Weakley, J. The effects of repeated-sprint training vs. short-bout high-intensity interval training on hamstring architecture and physical fitness. J Strength Cond Res 39(5): e620-e627, 2025-The aim of the study was to quantify and compare the effects of repeated-sprint training (RST) vs. short-bout high-intensity interval training (HIIT) on hamstring architecture and physical fitness in rugby league players. A parallel, 2-group, pretest posttest design was used, whereby 24 representative U20 players were assigned to either RST or short-bout HIIT for a 6-week intervention delivered alongside usual training. Assessments of biceps femoris long-head (BFlh) muscle architecture, countermovement jump (CMJ), eccentric hamstring strength, sprint force-velocity power (FVP) profiles, and 1,200 m shuttle run time (i.e., aerobic fitness) were performed. Compared with baseline, the RST group was associated with moderate improvements in aerobic fitness (change ±90% confidence interval [CI]: -4 ± 5 seconds) and maximal theoretical velocity (0.11 ± 0.10 m·s-1), as well as a moderate increase in BFlh fascicle length (1.05 ± 0.46 cm), a small increase in BFlh muscle thickness (0.12 ± 0.16 cm), and a moderate reduction in the BFlh pennation angle (-0.85 ± 0.64°). The short-bout HIIT group was associated with a moderate improvement in aerobic fitness (-10 ± 4 seconds) and a small improvement in CMJ peak power (1.4 ± 1.4 W·kg-1), as well as a large increase in BFlh fascicle length (0.99 ± 0.44 cm), a moderate increase in BFlh muscle thickness (0.15 ± 0.13 cm), and a small reduction in the BFlh pennation angle (-0.67 ± 0.50°). Changes in aerobic fitness were greater for short-bout HIIT when compared to RST, and this difference was moderate (effect size ±90% CI: 0.89 ± 0.82; pMET 0.108). Conversely, changes in 10-m sprint (0.82 ± 0.66; pMET 0.062), 20-m sprint (0.95 ± 0.71; pMET 0.043), 30-m sprint (0.104 ± 0.73; pMET 0.031) times, and certain FVP characteristics, were greater for RST, and these differences were moderate. Both groups increased fascicle length, but RST was more effective at improving sprint speed, while short-bout HIIT was more effective for improving aerobic fitness. Collectively, our findings demonstrate the potential benefits of these conditioning methods, which may cause morphological, physiological, and neuromuscular adaptations in athletes when applied alongside usual training practice.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":"39 5","pages":"e620-e627"},"PeriodicalIF":2.5,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143989047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}