Journal of Strength and Conditioning Research最新文献

{"title":"Unresisted Sprints Versus Heavy Resisted Sled Training: Relationships With Performance Indicators and Implications for Training Prescription in Elite Youth Rugby Players.","authors":"Santiago Zabaloy, Tomás T Freitas, Javier Gálvez-González, Eduardo Tondelli, Lucas A Pereira, Irineu Loturco","doi":"10.1519/JSC.0000000000005215","DOIUrl":"10.1519/JSC.0000000000005215","url":null,"abstract":"<p><strong>Abstract: </strong>Zabaloy, S, Freitas, TT, Gálvez-González, J, Tondelli, E, Pereira, LA, and Loturco, I. Unresisted sprints versus heavy resisted sled training: relationships with performance indicators and implications for training prescription in elite youth rugby players. J Strength Cond Res 39(9): 989-995, 2025-The aim of this study was to analyze the associations between sprint velocities achieved under unresisted and resisted (50% body mass [BM]) sprint conditions, squat 1-repetition maximum (squat 1RM) and its associated strength deficit (SDef; from 40 to 90% squat 1RM), and horizontal and vertical jump performance in elite youth rugby players. Twenty-five under-19 youth male rugby players ( n = 25; age: 17.3 ± 0.9 years) participated in this study and completed the following tests during the preparation period leading up to the 2024 in-season period: unresisted and resisted 30-m sprints, squat 1RM, countermovement jumps, and standing long jumps. Results showed that unresisted and resisted sprint velocities were significantly associated with both jump tasks ( r : 0.46-0.76; p < 0.019), while relative squat 1RM measures (i.e., 1RM relative to BM) demonstrated stronger correlations, compared with absolute 1RM values, with sprint velocities under both conditions, as well as with vertical and horizontal jump metrics ( r : 0.40-0.74; p < 0.045). SDefs across the entire range of loads (i.e., 40-90% squat 1RM) were also significantly associated ( r : 0.84-0.99; p < 0.001). In summary, the present findings highlight the importance of considering relative strength as an additional measure of strength performance, particularly when the primary objective is to enhance a wide range of sport-specific capabilities. Finally, the associations observed among all values of SDef indicate that reducing this strength-derived variable, especially under lighter loading conditions, is highly constrained or even impossible.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"989-995"},"PeriodicalIF":3.0,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144612183","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":"Effects of Rest Interval Configuration Between Sets on Volume Load During Five Sets of Bench Press and Back Squat Exercise.","authors":"Yuta Yamazaki, Kota Shimamori, Kazuki Takizawa, Taichi Yamaguchi, Keisuke Shibata","doi":"10.1519/JSC.0000000000005202","DOIUrl":"10.1519/JSC.0000000000005202","url":null,"abstract":"<p><strong>Abstract: </strong>Yamazaki, Y, Shimamori, K, Takizawa, K, Yamaguchi, T, and Shibata, K. Effects of rest interval configuration between sets on volume load during five sets of bench press and back squat exercise. J Strength Cond Res XX(X): 000-000, 2025-The present study examined the effect of 3 different rest interval configurations between sets on volume load during 5 sets of bench press (BP) and back squat (SQ) exercises. Thirteen recreationally resistance-trained male subjects (22.3 ± 3.9 years, 173.8 ± 7.3 cm, 73.5 ± 6.1 kg, BP 1 repetition maximum [1RM]: 90.6 ± 12.6 kg, SQ 1RM: 124.4 ± 23.0 kg) performed 5 sets of BP and SQ at 85% of 1RM load until momentary failure for the following 3 trials in random order; BP followed by SQ using 4- (4-minute trial) and 8-minute rest intervals between sets (8-minute trial), and BP with SQ performed alternately with a 4-minute rest interval between the 2 exercises to provide a 8-minute rest interval between each exercise (Alternating trial). The volume load in BP for the 8-minute trial (2,164.0 ± 519.1 kg) was significantly ( p < 0.01) greater than that of the 4-minute trial (1,668.3 ± 365.9 kg), and Alternating trial (1911.3 ± 453.9 kg) did not differ from the other 2 trials. The volume load in SQ for the 8-minute trial (2,899.2 ± 471.9 kg) and Alternating trial (2,777.7 ± 814.0 kg) were significantly ( p < 0.01, p < 0.05, respectively) greater than that of the 4-minute trial (2,336.7 ± 618.5 kg). These results suggest that prolonging rest interval between sets contributes to increase volume load in BP and SQ, and alternately performed the 2 exercises are beneficial for both improving volume load and time efficiency.</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":"144612145","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":"Influence of Proximity to Failure, Relative Intensity, and Volume on Voluntary Performance and Fatigue Symptoms After Resistance Training: A Systematic Review.","authors":"Daniel Varela-Olalla, Juan Del Campo-Vecino, Carlos Balsalobre-Fernández","doi":"10.1519/JSC.0000000000005194","DOIUrl":"10.1519/JSC.0000000000005194","url":null,"abstract":"<p><strong>Abstract: </strong>Varela-Olalla, D, del Campo-Vecino, J, and Balsalobre-Fernández, C. Influence of proximity to failure, relative intensity, and volume on voluntary performance and fatigue symptoms after resistance training: a systematic review. J Strength Cond Res 39(9): e1129-e1168, 2025-Fatigue management is of paramount importance and holistic approaches that include neuromuscular and perceptual factors have been developed in recent years because knowledge of the sites of the neuromuscular system that can be altered, and its perceptual impact, is mandatory for programing adequate stimulus-fatigue ratios. Most of the information in this regard comes from continuous whole-body exercise and isometric training, with less information regarding holistic fatigue analysis during traditional resistance training (RT). This review aims to analyze the influence of RT variables on voluntary performance, neuromuscular and perceived fatigue variables. Search was performed on PubMed and Web of Science following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, using terms related to resistance training and fatigue. Records were included if they provide comparisons between RT protocols in terms of acute fatigue in healthy humans. Results from fifty-one articles were included which indicate that contractile function, afferent feedback and perceptual responses are more affected during RT than muscle activation parameters being set duration, proximity to failure and total volume the main determinants of the impairments. Higher fatigue is induced as sets approach failure with high training volumes and densities, especially for protocols using light loads.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"e1129-e1168"},"PeriodicalIF":3.0,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144612208","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":"Minimal Role of Hamstring Hypertrophy in Strength Transfer Between Nordic Hamstring and Stiff-Leg Deadlift: A Blinded Randomized Controlled Trial.","authors":"Titouan Morin, Valentin Doguet, Antoine Nordez, Arnault Caillet, Lilian Lacourpaille","doi":"10.1519/JSC.0000000000005159","DOIUrl":"10.1519/JSC.0000000000005159","url":null,"abstract":"<p><strong>Abstract: </strong>Morin, T, Doguet, V, Nordez, A, Caillet, A, and Lacourpaille, L. Minimal role of hamstring hypertrophy in strength transfer between Nordic hamstring and stiff-leg deadlift: a blinded randomized controlled trial. J Strength Cond Res 39(9): 924-932, 2025-Strength transfer refers to the gain in strength in a nontrained exercise resulting from training another exercise. This study aims to determine whether whole and selective hamstring hypertrophy influences the magnitude of strength transfer between the Nordic hamstring exercise (NHE) and the stiff-leg deadlift (SDL). Using a blinded randomized controlled design, 36 resistance-untrained individuals were assigned to a control group (CON), an NHE group, or an SDL group. The 2 resistance training programs were performed 3 times per week for 9 weeks. Semimembranosus (SM), semitendinosus (ST), and biceps femoris (BF) hypertrophy was estimated from changes in the muscle volume using 3D ultrasound. Strength transfer was measured by changes in the 1RM of the nontrained exercise. After the resistance training programs, similar and significant whole hamstring hypertrophy was observed in both training groups (NHE: 11.4 ± 6.5%, and SDL: 7.0 ± 8.1%). The NHE group and SDL group presented a selective hypertrophy of ST (24.3 ± 10.8%) and SM (11.2 ± 12.7%), respectively. Conversely, no difference in strength transfer was observed between the NHE group (10.7 ± 8.5%) and the SDL group (20.7 ± 15.0%) ( p = 0.06; 95% CI 0.3-20.4%, d = 0.87). Finally, nonsignificant correlations were found between strength transfer and both whole and selective hamstring hypertrophy ( r ≤ 0.45), except for the BF in SDL ( r = 0.60). We conclude that hamstring hypertrophy has a minimal role in strength transfer in resistance-untrained individuals. These findings suggest that, even with hypertrophy, coaches and practitioners should include both Nordic hamstring and stiff-leg deadlift exercises in the same training program to enhance hamstring strength in knee flexion and hip extension tasks, benefiting both performance and injury prevention.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"924-932"},"PeriodicalIF":3.0,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144612211","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":"A Comparison of Force-Time and Muscle Activation Characteristics Between the Isometric Squat and Isometric Mid-Thigh Pull.","authors":"Lachlan P James, Charlie J Davids, Tomas Rodriguez-Anderson, Haresh T Suppiah, Benjamin F Mentiplay","doi":"10.1519/JSC.0000000000005198","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005198","url":null,"abstract":"<p><strong>Abstract: </strong>James, LP, Davids, CJ, Rodriguez-Anderson, T, Suppiah, HT, and Mentiplay, BF. A comparison of force-time and muscle activation characteristics between the isometric squat and isometric mid-thigh pull. J Strength Cond Res XX(X): 000-000, 2025-This investigation sought to establish the commonality of force-time curve characteristics between the isometric mid-thigh pull (IMTP) and isometric squat. In addition, the magnitude and timing of muscle activation (electromyography [EMG]) were examined at corresponding points on the force-time curve. Fifteen individuals (male: n = 12; age, 25.6 ± 4.7 years; body mass: 84.3 ± 9.2 kg; female: n = 3; age; 23.5 ± 4.9 years, body mass; 63.8 ± 12.4 kg) performed trials of the IMTP and the isometric squat while simultaneous measures of muscle activation were collected from the vastus medialis [VM], vastus lateralis [VL], biceps femoris [BF], and latissimus dorsi [LD]. A shared variance (r2) of 74% was found for net peak force between tests. A shared variance of 27-48% was demonstrated for early stage measures of force up to 200 ms from onset. Large (VM, VL) to very large (BF, LD) significant relationships for mean EMG were revealed between conditions. Large to very large significant relationships for each EMG epoch were present between conditions for VM and LD. Larger and significantly greater mean muscle activation of the BF occurred in the IMTP. Peak force from the IMTP and isometric squat represent a common aspect of maximal strength. However, given the limited commonality between tests for early force-time characteristics, performance in 1 condition should not be considered representative of performance in the other condition across these measures. Practitioners interested in greater hamstring contribution to lower body maximal strength may prefer the IMTP.</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":"144612142","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":"Training Impulse and Session Ratings of Perceived Exertion as Perceived by Athletes and Observed by Coaches During Preseason Football Camp.","authors":"Valerie Smith-Hale, Ruben Mendoza, Cody Vargo, Max Schoen, Linda Jimenez, Matthew VanSumeren, Jordan Sabourin, Brian C Rider, Jeffrey Martin, E Whitney G Moore, Tamara Hew-Butler","doi":"10.1519/JSC.0000000000005169","DOIUrl":"10.1519/JSC.0000000000005169","url":null,"abstract":"<p><strong>Abstract: </strong>Smith-Hale, V, Mendoza, R, Vargo, C, Schoen, M, Jimenez, L, VanSumeren, M, Sabourin, J, Rider, BC, Martin, J, Moore, W, and Hew-Butler, T. Training impulse and session ratings of perceived exertion as perceived by athletes and observed by coaches during pre-season football camp. J Strength Cond Res 39(9): 964-972, 2025-Quantification of internal training load (TL), through wearable technology, represents an emerging metric for TL management in sport. The accuracy of subjective vs. objective assessments of TL, as perceived by athletes and observed by coaches, has yet to be evaluated during long-duration football practices (>2 hours). The purpose of this study was to evaluate relationships among objective heart rate (HR) and subjective ratings of perceived exertion (RPE) assessment of TL in collegiate American football athletes, and their coaches, during preseason camp. Twenty-four athletes (first-year, n = 6; returning, n = 18) and 2 coaches (football coach [FBC], n = 1; strength and conditioning coach [SCC], n = 1) participated. Athletes wore chest strap HR monitors during the first 6 days of preseason football camp for an objective TL assessment using training impulse (TRIMP: average exercise HR × duration of practice). Subjective TL was assessed by both athletes (perceived) and coaches (observed) using a session ratings of perceived exertion (sRPE; 0-10 rating scale; 10 = maximum effort). The average practice duration was 142.3 ± 35.5 minutes, with 139 total observations across 6 practices. Significant (alpha level p ≤ 0.05) relationships were noted between TRIMP and sRPE from the athletes ( r = 0.62), FBC ( r = 0.68) and SCC ( r = 0.49). When subdivided into first-year and returning groups, relationships were stronger between TRIMP and sRPE with first-year athletes (athlete r = 0.68; p = 0.001; FBC r = 0.79; p = 0.001; SCC r = 0.64; p = 0.001) than for returning athletes (athlete r = 0.60; p = 0.001; FB coach r = 0.70; p = 0.001; SCC r = 0.40: p = 0.001). These data suggest that subjective athlete perceptions and coach observations of TL are in low-moderate agreement, indicating these are not interchangeable, during long-duration preseason football camp.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":"964-972"},"PeriodicalIF":3.0,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144612214","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":"Examining Countermovement Jump Performance and Dynamic Balance Among Male High School Athletes With Varying Levels of Sports Specialization.","authors":"Adam W VanZile, Daniel D Jones, Lydia J McHugh, Gracie L Clickovich, Marissa A Morales, Ryan K Reimschisel, Tricia L Widenhoefer, Jacqueline T Baughman, Mario D Urquidi, Dylan J Conner, Ward C Dobbs, Andrew R Jagim, Joel A Luedke, Thomas G Almonroeder","doi":"10.1519/JSC.0000000000005200","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005200","url":null,"abstract":"<p><strong>Abstract: </strong>VanZile, AW, Jones, DD, McHugh, LJ, Clickovich, GL, Morales, MA, Reimschisel, RK, Widenhoefer, TL, Baughman, JT, Urquidi, MD, Conner, DJ, Dobbs, WC, Jagim, AR, Luedke, JA, and Almonroeder, TG. Examining countermovement jump performance and dynamic balance among male high school athletes with varying levels of sports specialization. J Strength Cond Res XX(X): 000-000, 2025-Specializing at a young age may limit an athlete's motor development, since focusing on a single sport potentially exposes athletes to less variety of movements and neuromuscular demands. However, there are few studies examining the association between sport specialization and movement performance/control. The purpose of this study was to compare countermovement jump performance and dynamic balance among high school athletes of varying levels of sports specialization. 110 male high school athletes completed countermovement jump testing and the Y-Balance Test (YBT). Ground reaction forces were recorded during countermovement jumps and used to derive peak force, peak velocity, peak power, jump height, and the modified reactive strength index. Y-Balance Test composite scores were calculated to assess dynamic balance across multiple directions, for the dominant and non-dominant limbs. Athletes were grouped into high (n = 46), moderate (n = 39), and low (n = 25) specialization groups based on their sport participation habits. There were no between-group differences for any of the countermovement jump metrics (p > 0.05). For the YBT composite scores, there was not a group-by-limb interaction effect (p = 0.28); however, there was a main effect of group (p = 0.03). Post hoc tests indicated that the high specialization group exhibited lower YBT composite scores compared to the moderate specialization group (p = 0.01) and a trend toward lower scores compared to the low specialization group (p = 0.05). In general, highly specialized male athletes exhibited poorer dynamic balance compared to less specialized athletes.</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":"144612207","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 Athletic Profile on Acute Neuromuscular Response to a Repeated Sprint Protocol in Youth Females: A Pilot Study.","authors":"Jamie Salter, Dale Forsdyke, Zoe Dawson, Jacob Rymer, Luke Walsh, Peter Mundy","doi":"10.1519/JSC.0000000000005125","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005125","url":null,"abstract":"<p><strong>Abstract: </strong>Salter, J, Forsdyke, D, Dawson, Z, Rymer, J, Walsh, L, and Mundy, P. The influence of athletic profile on acute neuromuscular response to a repeated sprint protocol in youth females: A pilot study. J Strength Cond Res 39(7): 760-769, 2025-Athletic profiles influence how athletes tolerate exposure to high-intensity activities and training-induced fatigue. Current understanding of athletic profiles has been derived primarily from adult male populations that limits the application of this potentially important training knowledge to women, and in particular youth women. Therefore, this study aimed to address this bias and examine the influence of athletic profiles on acute neuromuscular response in 118 female multisport athletes aged between 8 and 22 years (age: 13.6 ± 2.9; stature: 155.9 ± 13.9; body mass: 50.2 ± 16.1). All subjects completed sprint speed (5, 40 m, and maximal sprint speed [MSS]) and strength characteristics (isometric midthigh pull) immediately before and after a repeated sprint protocol. Anaerobic Speed Reserve was calculated from performance tests (MSS and maximal aerobic speed) with subjects subsequently categorized (slow, hybrid, or fast). Excluding relative peak force, there were significant differences in all sprint speed and strength characteristics between slow and hybrid and significant differences between slow and fast profile athletes before repeated sprinting. Dependent t-tests revealed significant (p = 0.001, d = 0.58) reductions in 40 m performance for fast athletes and a significant decrease in MSS for both hybrid (p = 0.003, d = 0.47) and fast athletes (p = 0.002, d = 0.58). This suggests that female athletes with hybrid and fast athletic profiles may experience greater negative neuromuscular response after repeated sprints. Practitioners should therefore consider individualizing training and monitoring neuromuscular response to training to prevent athletic profile-related performance reductions, overreaching, or injury accumulating over time.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":"39 7","pages":"760-769"},"PeriodicalIF":3.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145149445","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":"Relationship Between Handgrip Strength and Vertical Jump Performance in Olympic Female Volleyball Athletes.","authors":"Damjana V Cabarkapa, Dimitrije Cabarkapa, Vladimir Bankovic, Andrew C Fry","doi":"10.1519/JSC.0000000000005165","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005165","url":null,"abstract":"<p><strong>Abstract: </strong>Cabarkapa, DV, Cabarkapa, D, Bankovic, V, and Fry, AC. Relationship between handgrip strength and vertical jump performance in Olympic female volleyball athletes. J Strength Cond Res 39(7): 809-814, 2025-The purpose of this study was to examine the relationship between maximal upper-body strength assessed using a handgrip dynamometer and lower-body strength and power-producing capabilities assessed through countermovement vertical jump (CMJ). Sixteen female Olympic volleyball players volunteered to participate in the present investigation. After completing the warm-up routine, all athletes performed 3 CMJs with hands on hips (i.e., no arm swing) while standing on a dual uniaxial force plate system sampling at 1,000 Hz. The following metrics were derived from the force plate system: eccentric peak and mean force, concentric peak and mean force, and vertical jump height (i.e., impulse-momentum calculation). After the completion of the CMJ testing protocol, the handgrip strength was assessed using a digital dynamometer. Pearson product-moment correlation coefficients were used to measure the strength of linear regressions (p < 0.05). The results revealed moderate to strong associations between handgrip strength and CMJ performance (r = 0.415-0.696). Specifically, the dominant handgrip strength revealed a statistically significant relationship with 8 of 9 force-time metrics of interest (e.g., eccentric peak force, concentric mean power, and jump height), while the nondominant hand demonstrated a positive association with only 5 of 9 CMJ performance metrics. These results suggest that within this specific cohort of athletes, the strength of the dominant hand might be a better predictor of the overall CMJ performance, including both eccentric and concentric force and power-producing capabilities, as some of the foundational physical attributes that volleyball athletes need to possess.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":"39 7","pages":"809-814"},"PeriodicalIF":3.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145149052","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":"Validity and Reliability of Flywheel Resistance Technology as an Assessment Method and Its Association With Sports Performance and Asymmetry: A Systematic Review.","authors":"Mark C W Mak, Chris Bishop, Marco Beato","doi":"10.1519/JSC.0000000000005146","DOIUrl":"10.1519/JSC.0000000000005146","url":null,"abstract":"<p><strong>Abstract: </strong>Mak, MCW, Bishop, C, and Beato, M. Validity and reliability of flywheel resistance technology as an assessment method and its association with sports performance and asymmetry: A systematic review. J Strength Cond Res 39(7): e930-e948, 2025-Flywheel technology is commonly used in training but remains underused for monitoring and testing. Flywheel devices can provide valuable data from mechanical outputs during both concentric and eccentric movements. This systematic review assesses its validity and reliability for evaluating sports performance and limb asymmetry. Searches were conducted in PubMed, SPORT-Discus, Google Scholar, and Web of Science following PRISMA DTA guidelines, focusing on keywords related to flywheel testing. Results show that flywheel testing is reliable (intraclass correlation coefficient = 0.66-0.99, r = 0.69-0.97, α = 0.85-0.98) and valid for the athletic population when subjects undergo 2 familiarization sessions. The test can be conducted using rotary encoders, force plates, linear encoders, or inertial measurement units. Subjects may perform 1-2 prerepetitions followed by 5-10 recording repetitions with 1-4 sets and 2-3 minutes of rest between sets. Moment of inertia can be customized based on the athlete's experience and the type of flywheel device used. Key metrics for assessment encompass speed, force, and power, with peak power being the most commonly used parameter. Few samples of evidence showed that increased asymmetry in concentric power may negatively affect change of direction performance, emphasizing the need for more high-quality studies. In conclusion, flywheel technology offers valuable insights across various movements, providing strength and power assessment while potentially improving athletic performance and injury prevention. Continued research is vital to explore its effectiveness in diverse athletic contexts.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":"39 7","pages":"e930-e948"},"PeriodicalIF":3.0,"publicationDate":"2025-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144675072","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}