Journal of Strength and Conditioning Research最新文献

{"title":"Sex-Specific Adverse Association of Endocrine Disrupting Chemicals on Peak Anaerobic Power and Skeletal Muscle Mass of Active Young Adults.","authors":"Julia Matzenbacher Dos Santos, Taylor Kennedy, Jiayi Zhu, Alexandra McPike, Mitali Ray, Jill Demirci, Jason Dechant","doi":"10.1519/JSC.0000000000005223","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005223","url":null,"abstract":"<p><strong>Abstract: </strong>dos Santos, JM, Kennedy, T, Zhu, J, McPike, A, Ray, M, Demirci, J, and Dechant, J. Sex-specific adverse association of endocrine disrupting chemicals on peak anaerobic power and skeletal muscle mass of active young adults. J Strength Cond Res XX(X): 000-000, 2025-Endocrine disrupting chemicals, such as bisphenol A (BPA) and bisphenol S (BPS), and polycyclic aromatic hydrocarbons (PAHs) are a broad class of industrial compounds that induce adverse physiologic outcomes dependent on biologic sex. These chemicals stimulate oxidative stress and impair pathways involved in anaerobic and aerobic energy generation, key drivers of athletic performance. This study aims to analyze the association of BPA, BPS, 2-naphthol (a marker of PAH), and oxidative stress with peak anaerobic power (PAP) and anthropometric characteristics. Peak anaerobic power was assessed in active men and women (n = 54, age 20 ± 1.4, body mass index 25.4 ± 3.8 kg·m-2) using a vertical jump test. Fasting levels of urinary BPA, BPS, 2-naphthol, oxidative stress, blood glucose, and muscle mass were assessed by ELISA, capillary sample analysis, and body composition analyzer, respectively. Peak anaerobic power was negatively associated with BPA and positively with percentage of skeletal muscle and oxidative stress (p < 0.05). Multivariate regression, moderated by nonmodifiable variables associated with PAP such as sex, height, and age, indicated that only BPA was a predictor of PAP (β = -0.186, p = 0.021). Relationships of variables were assessed in each sex, and PAP was negatively associated with levels of BPA and 2-naphthol in woman. Multivariate regression confirmed that those variables are predictors of PAP (p < 0.01). Results support the idea of a sex-specific physiologic impact of BPA and 2-naphthol on PAP, independently of levels of oxidative stress and percentage of muscle. Controlling BPA and 2-naphthol exposure could be a potential strategy to improve PAP in female athletes.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144958572","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 Relationship Between External and Internal Load, Sleep, and Wellness During an Off-Season Phase in Women's Collegiate NCAA Division I Lacrosse Athletes.","authors":"Paige J Sutton, Harry P Cintineo, Petey W Mumford, Kyle L Sunderland","doi":"10.1519/JSC.0000000000005235","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005235","url":null,"abstract":"<p><strong>Abstract: </strong>Sutton, PJ, Cintineo, HP, Mumford, PW, and Sunderland, KL. The relationship between external and internal load, sleep, and wellness during an off-season phase in women's collegiate NCAA Division I lacrosse athletes. J Strength Cond Res XX(X): 000-000, 2025-The purpose of this study was to investigate the bidirectional associations between workload, recovery, sleep, and wellness during the off-season in collegiate women's lacrosse athletes. Data from 20 athletes were evaluated throughout 2 weeks of off-season. Workload was determined by Edwards Training Impulse (eTRIMP), total distance (TD), high-speed running distance (HSR), and session rating of perceived exertion-derived internal training load (sRPE-TL). Resting heart rate and heart rate variability were measured during a 10-minute period upon waking each morning. A Consensus Sleep Diary and Modified Hooper wellness questionnaires were completed within 60 minutes of waking to determine sleep efficiency (SE), sleep onset latency, wake after sleep onset (WASO), total sleep time, and wellness scores. Repeated-measures correlations determined the bidirectional relationships between workload and measures of sleep and wellness (α = 0.05). Total distance, eTRIMP, and sRPE-TL inversely correlated with the following night's SE (r = -0.204, -0.218, and -0.172, respectively) and SE positively correlated with same-day TD (r = 0.222) and eTRIMP (r = 0.199). This relationship was attributable to WASO, with both TD (r = 0.187) and eTRIMP (r = 0.179) having positive correlations with WASO. A positive correlation with session duration was observed for TD (r = 0.811), eTRIMP (r = 0.914), HSR (r = 0.417), and sRPE-TL (r = 0.168). Significant associations between workload, sleep, and wellness outcomes were found, with WASO and session duration emerging as key factors. Although we observed associations between workload, subjective wellness, sleep outcomes, the small-to-moderate relationship strengths suggest other contributing factors. Practitioners should prioritize sleep hygiene education to help athletes mitigate potential sleep disruptions caused by training.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144958637","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":"Optimizing Resistance Training Outcomes: Comparing In-Person Supervision, Online Coaching, and Self-Guided Approaches: A Randomized Controlled Trial.","authors":"Simon Gavanda, Steffen Held, Sascha Schrey, Katharina Oberwetter, Pier-Gino M Lazzaro, Markus Pergelt, Stephan Geisler","doi":"10.1519/JSC.0000000000005216","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005216","url":null,"abstract":"<p><strong>Abstract: </strong>Gavanda, S, Held, S, Schrey, S, Oberwetter, K, Lazzaro, P-GM, Pergelt, M, and Geisler, S. Optimizing resistance training outcomes: comparing in-person supervision, online coaching, and self-guided approaches: a randomized controlled trial. J Strength Cond Res XX(X): 000-000, 2025-This randomized, parallel-group trial investigated the effects of supervised (SUP), app-guided (APP), and self-guided (PDF) 10-week, thrice-weekly full-body resistance training (RT) on strength, body composition, well-being, and supervision satisfaction (S-SRQ) in trained men and women (n = 79, 48% women; 30.7 ± 7.8 years, 1.75 ± 0.1 m, 77.5 ± 17.5 kg). Adherence was highest in SUP (88.2%), followed by APP (81.2%) and PDF (52.2%). At p ≤ 0.05, body mass (+1.8 ± 1.9 kg, p = 0.006) and fat-free mass (+1.4 ± 0.9 kg, p ≤ 0.001) increased significantly in SUP. Muscle mass gains were observed in SUP (+1.4 ± 0.9 kg, p = 0.009) and PDF (+0.9 ± 1.3 kg, p = 0.047). All groups improved squat 1-repetition maximum (1RM) (SUP: +26.6 ± 6.5 kg, p ≤ 0.001; APP: +19.2 ± 11.0 kg, p ≤ 0.001; PDF: +19.4 ± 11.7 kg, p ≤ 0.001) and bench press 1RM (SUP: +9.1 ± 3.5 kg, p ≤ 0.001; APP: +8.2 ± 4.0 kg, p ≤ 0.001; PDF: +7.7 ± 5.8 kg, p ≤ 0.001). Supervised showed significantly greater squat gains than APP and PDF (p ≤ 0.044). Well-being (WHO-5) improved in SUP (+15.7 ± 16.2 points, p ≤ 0.001) and PDF (+9.0 ± 20.4 points, p = 0.032). Satisfaction with supervision was significantly higher in SUP (96.7 ± 4.3%) than in APP (92.0 ± 7.1%, p = 0.005). In conclusion, supervised RT resulted in superior improvements in strength, body composition, well-being, and supervision satisfaction compared with app-guided or self-guided training. Although APP and PDF resulted in some positive effects, their magnitude was generally smaller. These findings underscore the value of in-person coaching in optimizing RT outcomes. However, app-based RT shows promise for maintaining adherence, offering a viable alternative when full supervision is not feasible.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144731943","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":"Conducting Resisted Sled Sprint Load-Velocity Profiling in Female Rugby League Athletes-Reliability and Sled Load Using Velocity Decrement.","authors":"Andrew Martin, Steven Duhig, Matthew Bourne, Clare Minahan, Phillip Bellinger","doi":"10.1519/JSC.0000000000005227","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005227","url":null,"abstract":"<p><strong>Abstract: </strong>Martin, A, Duhig, S, Bourne, M, Minahan, C, and Bellinger, P. Conducting resisted sled sprint load-velocity profiling in female rugby league athletes-Reliability and sled load using velocity decrement. J Strength Cond Res XX(X): 000-000, 2025-Resisted sled sprinting (RSS) is a training method used to improve short distance sprinting performance. Previous research has individualized sled loads using a 50% velocity decrement (VDEC) to achieve an optimum load (LOPT percentage of body mass [%BM]) targeting maximum power output (Pmax [W·kg-1]). However, RSS load-velocity (L-v) profiling to determine a 50% VDEC has predominantly been conducted in male cohorts. Sampling exclusively female athletes, the aims of this study are to (a) determine the interday reliability of the L-v slope and LOPT at 50% VDEC and (b) provide L-v profiling protocol recommendations for sled loading and relative trial distances. Sixteen female rugby league athletes (age: 21.29 ± 7.09 years; BM: 74.94 ± 11.42 kg; height: 1.71 ± 0.05 m) completed a minimum of 2 familiarization sessions followed by L-v testing on 2 days 7 days apart. Using the coefficient of variance (CV), an acceptable absolute interday reliability of LOPT (%BM) was found when derived from trial peak velocity (Vpeak) and trial average velocity of the maximum velocity plateau (VAVGMVP) (CV = 1.82-4.39%, CV = 1.33-5.09%). Poor to excellent or good relative reliability was determined for Vpeak (intraclass correlation coefficient [ICC3,1] = 0.73 [0.26 to 0.90]) and VAVGMVP (ICC3,1 = 0.62 [-0.12 to 0.87]). Using Vpeak (m·s-1) and VAVGMVP (m·s-1) methods, the %BM required to induce a 50% VDEC ranged from ≈59 to 72% BM and from ≈58 to 71% BM, respectively. Resisted sled sprinting L-v profiling load protocols are recommended to range between 25 and 100% BM to achieve a reliable L-v slope, while relative trial distances should range between 10 and 30 m in female field sport athletes.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144742366","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 Local Cold Application and Resistance Exercise on the mRNA Response of Skeletal Muscle.","authors":"Mark L McGlynn, Alejandro M Rosales, Christopher W Collins, Dustin R Slivka","doi":"10.1519/JSC.0000000000005209","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005209","url":null,"abstract":"<p><strong>Abstract: </strong>McGlynn, ML, Rosales, AM, Collins, CW, and Slivka, DR. The influence of local cold application and resistance exercise on the mRNA response of skeletal muscle. J Strength Cond Res XX(X): 000-000, 2025-Cold application post exercise is common practice despite empirical evidence suggesting it impairs muscle growth signaling. Our purpose was to determine the effects of local cold application and resistance exercise on muscle growth/breakdown gene expression. Twelve subjects completed a bilateral resistance exercise bout to volitional fatigue (leg press, leg extension) while wearing a thermal wrap on 1 limb (10° C fluid, EX + COLD) and no wrap contralaterally (EX). Bilateral vastus lateralis biopsies, skin temperature, and intramuscular temperature were collected pre intervention, post resistance exercise (temperatures only), and 4 hours post exercise. Statistical significance was set at p < 0.05. After 4 hours of cooling, skin (p < 0.001) and intramuscular temperatures (p < 0.001) were lower in the EX + COLD (20.4 ± 0.6, 26.1 ± 0.9° C) than in the EX limb (31.7 ± 0.6, 35.1 ± 0.3° C). Despite these temperature decreases, local cooling did not differentially influence myogenic and proteolytic gene expression (p > 0.05). Resistance exercise was the primary influence on gene expression change. Favorable myogenic gene expression changes were exhibited by Myogenin (increase, p = 0.007), Myogenic Factor 6 (increase, p = 0.002), and Myostatin (decrease, p < 0.001). However, myogenic gene Myogenic Factor 5 decreased (p < 0.001). All other myogenic genes went unchanged (Myogenic Differentiation 1, p = 0.665; Myocyte Enhance Factor 2a, p = 0.074; Ribosomal Protein S3, p = 0.773; Ribosomal Protein L3-Like, p = 0.118). Proteolytic gene expression changes were exhibited by Muscle Unique Ring Finger 1 (increase, p = 0.002) and Atrogin-1 (decrease, p = 0.020). However, F-box protein 32 went unchanged (p = 0.980). Local cooling may be paired with a resistance exercise bout because of minimal influence after 4 hours of cooling on skeletal muscle growth/breakdown mRNA signaling.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144742367","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":"Relative Energy Deficiency in Sport in Rock Climbers: A Narrative Review.","authors":"Kenneth Tan, Volker Schöffl","doi":"10.1519/JSC.0000000000005157","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005157","url":null,"abstract":"<p><strong>Abstract: </strong>Tan, K and Schöffl, V. Relative energy deficiency in sport in rock climbers: a narrative review. J Strength Cond Res 39(8): 908-917, 2025-Rock climbing has experienced immense growth in popularity over the years and was incorporated into the summer Olympic program as of the 2020 Tokyo Olympics. Previously known as Female Athlete Triad, relative energy deficiency in sport (REDs) refers to a preventable syndrome characterized by impaired physiologic functions because of low energy availability (LEA). This leads to a multitude of symptoms and compromises the health and performance of climbers. Understanding how REDs manifests in the context of climbing is important for injury prevention, ensuring safe and sustainable practices of the sport, and future research. This review comprehensively explores REDs in the setting of climbing, providing a detailed literature review including the most current research published in 2024. We shed light on the latest recommendations made by the International Olympic Committee, discuss the physiology of climbing, and review studies on anthropometry and nutrition, touching on the youth, adult, able-bodied, and para-athlete populations. Because many rock climbers take the profile of having a low BMI and body fat percentage, there is a concerning number of high-level climbers who do not meet the required nutritional status or energy requirements to sustain a moderate level of training. This article highlights the importance of implementing a multidisciplinary team-based approach in developing an individualized dietary plan for climbers with problematic LEA, underscoring the need for recognizing, diagnosing, and implementing holistic care strategies while also highlighting areas that require further advancement in the field.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":"39 8","pages":"908-917"},"PeriodicalIF":3.0,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144958401","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":"Reliability and Validity of Stryd for Measuring Running Kinematics During an Incremental Treadmill Test.","authors":"Aitor Pinedo-Jauregi, Eñaut Ozaeta-Beaskoetxea","doi":"10.1519/JSC.0000000000005207","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005207","url":null,"abstract":"<p><strong>Abstract: </strong>Pinedo-Jauregi, A and Ozaeta-Beaskoetxea, E. Reliability and validity of Stryd for measuring running kinematics during an incremental treadmill test. J Strength Cond Res XX(X): 000-000, 2025-Inertial Measurement Unit devices have become indispensable tools for coaches and researchers. In particular, the Stryd device has been used by coaches to improve athletes' running performance. However, its reliability and validity have not been universally accepted by the scientific community. The aim of this study was to assess the reliability and validity of the Stryd device during an incremental running test. For this purpose, subjects performed an incremental test at speeds ranging from 8 to 17 km·h-1. Reliability was tested using 2 Stryd devices placed on the same foot, while validity was assessed against the Optojump Next. The results showed that the Stryd device is reliable for measuring power, cadence, ground contact time (GCT), and leg stiffness (coefficients of variation < 3.34%; intraclass correlation coefficients >0.81; SEM <0.51; r > 0.88), but not for vertical oscillation. In terms of validity, the device was found to be valid for measuring cadence (Lin's Concordance Coefficient > 0.78; Mean Absolute Percent Error <2.18%), but not for GCT. In conclusion, the Stryd device seems reliable and valid for some variables, but not for others. The authors advise trainers and scientists using the Stryd device to be cautious, because its measurements are not fully supported by the scientific community.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144642801","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 Time-Course of Hamstring Muscle Passive Stiffness and Perceived Tightness After Strenuous Exercise: Is It Time to Start Using Localized Stiffness Measurements?","authors":"Dries Pieters, Erik Witvrouw, Adelheid Steyaert, Luc Vanden Bossche, Joke Schuermans, Sandro Freitas, Evi Wezenbeek","doi":"10.1519/JSC.0000000000005204","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005204","url":null,"abstract":"<p><strong>Abstract: </strong>Pieters, D, Witvrouw, E, Steyaert, A, Vanden Bossche, L, Schuermans, J, Freitas, S, and Wezenbeek, E. The time-course of hamstring muscle passive stiffness and perceived tightness after strenuous exercise: Is it time to start using localized stiffness measurements? J Strength Cond Res XX(X): 000-000, 2025-Hamstring injuries are inherent to high-speed running sports. Postexercise muscle stiffness is suggested as a potential risk factor, yet an objective measurement tool to monitor its time-course was lacking. Interestingly, shear wave elastography (SWE) is an objective measurement of tissue stiffness. Surprisingly, the time-course of postexercise hamstring muscle passive stiffness (measured with SWE) and how this relates to the subjective perception of tightness have insufficiently been examined. Therefore, the aim was to determine and compare the time-course of the localized passive stiffness of the hamstring muscles (using SWE) with the perceived overall hamstring tightness after an exhaustive exercise. Twenty-four subjects underwent a prone-leg-curl exercise until full exhaustion. At 6 moments in time (baseline, 0, 24, 48, 72, and 96 h postexercise), the passive stiffness was quantified in each hamstring head through SWE and the perceived hamstring tightness through a numeric rating scale. Mixed models were used to investigate the effect of maximal exercise on the behavior of both the passive muscle stiffness and perceived tightness of the hamstrings. The level of significance was set at α = 0.05. Concerning the stiffness behavior of the semimembranosus and biceps femoris long head muscles, no significant changes were found over time (p > 0.05). However, the shear modulus of the semitendinosus muscle increased significantly, reaching its maximum 48 h postexercise (+9.7%, p = 0.012) followed by a significant decrease (-7.8%, p = 0.024) to baseline level after 96 h. In contrast, the perceived hamstring tightness peaked at 24 h (p < 0.001), significantly decreased between 24 and 48 h (p = 0.036), with a normalization after 96 h (p < 0.001). Thus, the time-course of the athlete's perceived hamstring tightness after strenuous exercise did not follow the localized hamstring passive stiffness, suggesting that precaution should be taken when designing training and recovery programs.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144642802","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":"Integration of a Knee Flexor Bias or Hip Hinge Bias Resistance Training Program With Combined High-Speed Running in Academy Soccer Players.","authors":"Steven Ross, Nicholas J Ripley, John J McMahon, Paul Comfort","doi":"10.1519/JSC.0000000000005210","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005210","url":null,"abstract":"<p><strong>Abstract: </strong>Ross, S, Ripley, NJ, McMahon, JJ, and Comfort, P. Integration of a knee flexor bias or hip hinge bias resistance training program with combined high-speed running in academy soccer players. J Strength Cond Res XX(X): 000-000, 2025-Strength training has been shown to mitigate risk of hamstring strain injury and enhance athletic performance. However, most training studies are focused on single exercise interventions and, therefore, lacking in ecological validity. In this study, we investigated the effects of combined resistance training and curvilinear high-speed running, with resistance training sessions having either a hip hinge bias (Romanian deadlift; RDL) or knee flexor bias (Nordic hamstring exercise; NHE), on knee flexor strength, jump, and sprint performance. In total, 37 male academy soccer players (17.1 ± 0.2 years; height, 178.3 ± 2.5 cm; body mass, 70.6 ± 0.7 kg) were randomized into 3 groups (RDL, NHE, and control) and completed 6 weeks of training. Knee flexor strength was improved in both intervention groups compared with the control (p ≤ 0.05; g = 0.85-1.62); however, adaptations in sprint (g = 1.14-1.44) and jump performance (g = 1.08-1.57) were superior in the NHE group than in the RDL and control groups. The results of the study indicate that both interventions were effective in improving knee flexor strength and athletic performance, but interventions that include the NHE seem to be more effective.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144612209","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 Stretch-Shortening Cycle Function in Girls During Maturation and in Response to Training: A Narrative Review.","authors":"Lee D McGarrigal, Christopher I Morse, David T Sims, Georgina K Stebbings","doi":"10.1519/JSC.0000000000005191","DOIUrl":"10.1519/JSC.0000000000005191","url":null,"abstract":"<p><strong>Abstract: </strong>McGarrigal, LD, Morse, CI, Sims, DT, and Stebbings, GK. Development of stretch-shortening cycle function in girls during maturation and in response to training: A narrative review. J Strength Cond Res 39(8): e1043-e1051, 2025-The aim of this narrative review was to examine stretch-shortening cycle (SSC) function and to explore its effects on the athletic performance in girls during maturation and in response to plyometric training (PT), where there has been limited focus to date. The SSC is an integral component of explosive actions such as sprinting and jumping. Literature shows that the SSC develops during maturation because of several morphological, neurophysiological, and structural mechanisms, and that the SSC response can be amplified by training. Research suggests that boys experience \"accelerated adaptation\" in slow and fast SSC function as they mature, but to date, similar studies in girls are limited and often contradictory. Plyometric training capitalizes on the ability of the SSC to generate greater force production by including an eccentric muscle action quickly followed by a concentric action. However, the number of PT studies involving youth female athletes is lacking, with only 10% of all PT studies including female subjects aged <18 years. This is surprising given that PT can enhance athletic performance and reduce the risk of noncontact anterior cruciate ligament injuries in girls. After PT, boys experience \"synergistic adaptation,\" which is the symbiotic relationship between PT strategically programmed to coincide with the development of the SSC that is being concurrently enhanced by the processes of growth and maturation. Establishing if girls experience periods of accelerated and synergistic adaptation in slow and fast SSC function after PT would likely influence future training in this population, which has traditionally been underserved.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"e1043-e1051"},"PeriodicalIF":3.0,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144612144","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}