Journal of Strength and Conditioning Research最新文献

{"title":"Polyphenol-Rich Sorghum Bicolor Extract Enhances Strength Recovery After Eccentric Exercise.","authors":"Clara J Mitchinson, Minyoung Kwak, Pasquale J Succi, Brian Benitez, Haley C Bergstrom","doi":"10.1519/JSC.0000000000005144","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005144","url":null,"abstract":"<p><strong>Abstract: </strong>Mitchinson, CJ, Kwak, M, Succi, PJ, Benitez, B, and Bergstrom, HC. Polyphenol-rich sorghum bicolor extract enhances strength recovery after eccentric exercise. J Strength Cond Res XX(X): 000-000, 2025-This randomized, double-blind, placebo (PL) controlled trial examined the effects of a polyphenol-rich supplement on muscular strength recovery after eccentric exercise. Twenty-nine men (mean ± SD, age = 23.1 ± 3.8 years) were randomly assigned to a high- (500 mg·d-1; n = 9) or low- (250 mg·d-1; n = 10) dose polyphenol-rich sorghum bicolor extract, or PL (n = 10) group and completed a 17- to 18-day supplementation period, with eccentric exercise on day 14 + 1. Unilateral forearm flexion strength, muscle thickness (MT), pain pressure threshold (PPT), perceived recovery, and pain ratings were recorded before (baseline) and at 24, 48, and 72 hours after maximal eccentric exercise. Analyses included mixed-model ANCOVAs, ANOVAs, and post hoc Bonferroni corrected pairwise comparisons (p < 0.05). After 18-25% strength losses from baseline to 24 hours, strength increased significantly from 24 to 48 hours for the high-dose group (mean difference [CI95%] = 5.7 N·m [2.2-9.3]; p < 0.001; d = 0.568) and from 24 to 72 hours for the low-dose group (8.3 N·m [4.4-12.2]; p < 0.001; d = 0.848), while strength remained unchanged from 24 to 72 hours for the PL group (p = 0.101-1.000). There were no changes in MT or PPT from 24 to 72 hours. Pain ratings significantly decreased, and perceived recovery increased at 72 hours relative to 24 and 48 hours for all groups across time (p = 0.001-0.012). Supplementation with a high- and low-dose polyphenol-rich sorghum bicolor extract increased recovery of muscular strength at faster rates than PL after eccentric exercise but had no meaningful effect on muscle swelling, perceived pain, or recovery. A polyphenol-rich supplement may enhance performance in subsequent exercise sessions and promote increased training volume.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144506077","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":"How Strong Is Strong Enough? Assessing When Physical Performance Tests Cease to Be Predictive of Sprint Performance in Trained Football Players.","authors":"Shayne Vial, Mark Scanlan, Philipp Beranek, Daniel Kadlec, Oliver R Barley, Jodie Cochrane Wilkie","doi":"10.1519/JSC.0000000000005185","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005185","url":null,"abstract":"<p><strong>Abstract: </strong>Vial, S, Scanlan, M, Beranek, P, Kadlec, D, Barley, OR, and Cochrane Wilkie, J. How strong is strong enough? Assessing when physical performance tests cease to be predictive of sprint performance in trained football players. J Strength Cond Res XX(X): 000-000, 2025-Quantifying underlying capacities of sprint performance are useful for monitoring training and guiding interventions. Traditional statistical techniques, such as correlation and regression analyses, have been widely used to model relationships between physical capacity and sprint performance. However, these methods often assume linearity, potentially oversimplifying complex, nonlinear interactions, and generalizing group-level data that may misrepresent individual trends. For instance, strength metrics such as maximal half-squat strength have been correlated with sprint performance, suggesting that speed should increase proportionally with strength. Yet evidence indicates that, in practice, this relationship plateaus, with further gains yielding diminishing returns. Although general guidelines exist, no established methods exist for quantifying the individual contribution of physical performance metrics to sprint performance. Using a novel approach, this study identified the \"saturation point\" at which physical performance tests cease to predict sprint performance. We used random forest regression and partial dependence plots to analyze data from 60 male football players who completed strength (isometric mid-thigh pull [IMTP] and Nordic eccentric hamstring strength) and jump tests (countermovement jump and standing broad jump [SBJ]). The random forest model demonstrated high predictive power (R2 = 0.85-0.87) for 20 and 40 m sprint times, identifying IMTP and SBJ as key predictors. Partial dependence plots revealed a saturation effect for IMTP at 2.0 body mass and SBJ at 0.29 m·s-1, where further increases yielded diminishing returns on sprint performance. These findings suggest that while strength and power improvements benefit sprint performance, further gains beyond specific thresholds may contribute little to additional improvements in sprint performance.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144506063","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":"Isokinetic Knee Extension and Flexion Strength in Female Athletes at 20 and 40 Weeks After Bone-Patellar Tendon-Bone Anterior Cruciate Ligament Reconstruction.","authors":"Sofia E Klemola, Barry T Gorman, Neil Welch, Stacey M Kung","doi":"10.1519/JSC.0000000000005158","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005158","url":null,"abstract":"<p><strong>Abstract: </strong>Klemola, SE, Gorman, BT, Welch, N, and Kung, SM. Isokinetic knee extension and flexion strength in female athletes at 20 and 40 weeks after bone-patellar tendon-bone anterior cruciate ligament reconstruction. J Strength Cond Res XX(X): 000-000, 2025-Despite females' higher anterior cruciate ligament (ACL) injury risk, research assessing the rehabilitation of knee extensor and flexor strength after an ACL reconstruction (ACLR) with a bone-patellar tendon-bone (BPTB) graft in female athletes is limited. The purpose of this study was to investigate the restoration of knee extension strength in female athletes after ACLR with a BPTB graft, along with knee flexion strength, limb symmetry index (LSI), and return to sport (RTS) status. Eighty-nine 16-30-year-old female athletes who underwent a BPTB ACLR were eligible for analysis. Participants completed isokinetic knee extension and flexion strength testing at 20 ± 5 (T1) and 40 ± 5 (T2) weeks post-ACLR using an isokinetic dynamometer. Changes in peak knee extension and flexion torques, and LSI values were assessed in the injured and noninjured limbs from T1 to T2. RTS status was recorded at T2. Two-way repeated measures ANOVA analyzed peak extension and flexion torques and paired t-tests analyzed LSI. Statistical significance was set at p ≤ 0.05. Compared with the injured limb, the noninjured limb demonstrated a higher peak extension torque at T1 (p < 0.0001) and T2 (p < 0.0001) and a higher peak knee flexion torque at T1 only (p = 0.004). Peak knee extension (p < 0.0001) and flexion (p = 0.03) torque LSI were significantly higher at T2 than at T1. Despite significant improvements in knee extension and flexion strength, a deficit in the injured limb's knee extensor strength remained at 40 weeks postsurgery, which highlights the need for female athletes to prioritize strengthening the injured limb's knee extensors during rehabilitation, especially before returning to training and/or competition.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144506075","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 Impact of Localized Muscle Mass on Sprint Mechanics During the Swing and Stance Phases of Division I Collegiate American Football Players.","authors":"Casey J Metoyer, Jonathon R Lever, Megan McGinty, Loren Landow, Robert Hunt, Jonathan D Hauenstein, Alan Huebner, Michael H Stone, John P Wagle","doi":"10.1519/JSC.0000000000005163","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005163","url":null,"abstract":"<p><strong>Abstract: </strong>Metoyer, CJ, Lever, JR, McGinty, M, Landow, L, Hunt, R, Hauenstein, JD, Huebner, A, Stone, MH, and Wagle, JP. The impact of localized muscle mass on sprint mechanics during the swing and stance phases of Division I collegiate American football players. J Strength Cond Res XX(X): 000-000, 2025-This study evaluates the impact of localized muscle volume on sprint mechanics among Division-I collegiate American football players across 3 position groups: Skills (Defensive Backs, Wide Receivers), Mids (Linebackers, Running Backs, Tight Ends), and Bigs (Offensive, Defensive Linemen). A total of 108 male athletes (age: 21.4 ± 1.9 years, BMI: 29.6 ± 4.3) were assessed. Lower extremity muscle volumes were measured using magnetic resonance imaging, and sprint kinematics were captured using an inertial motor unit system during maximal effort sprints. Stepwise multiple linear regressions were conducted to evaluate the relationship between muscle volumes, stance, and swing times for each position group. In the Skills group, increased volumes in the vastus intermedius (β = -0.15, p < 0.01) and sartorius (β = -0.17, p = 0.01) were associated with reduced swing time, while those in the vastus medialis (β = 0.18, p < 0.01) increased swing time. For stance time, the gluteus maximus (β = -0.02, p = 0.03) was associated with reduced stance time, and the tibialis posterior (β = 0.28, p < 0.01) increased it. In the Mids group, the biceps femoris long head (β = -0.15, p < 0.01) was associated with reduced stance time, while the vastus medialis (β = 0.09, p < 0.01) increased it. In the Bigs group, the rectus femoris and sartorius were associated with reduced stance time, while the tensor fasciae latae and tibialis anterior increased stance time. These findings highlight the role of localized muscle volume in influencing sprint mechanics and emphasize the potential need for position-specific physical development programs tailored to the biomechanical demands of running mechanics in American football players.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144506079","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 Relative Rest and Team Performance Across Competitive Seasons in the National Football League.","authors":"Anthony G Pinzone, Yousuf Abu-Amara, Ryan W Gant, Jennifer Rivera, Emily C Tagesen, Jacob E Barkley, Adam R Jajtner","doi":"10.1519/JSC.0000000000005148","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005148","url":null,"abstract":"<p><strong>Abstract: </strong>Pinzone, AG, Abu-Amara, Y, Gant, RW, Rivera, J, Tagesen, EC, Barkley, JE, and Jajtner, AR. The relationship between relative rest and team performance across competitive seasons in the national football league. J Strength Cond Res XX(X): 000-000, 2025-This investigation aimed to assess the relationship between relative rest index (RRI) and team performance across multiple seasons of National Football League (NFL) competition. To examine this relationship, all NFL regular season games from the 1970-71 to 2022-23 NFL seasons (N = 12,290) were analyzed with rest intervals calculated for each team on a game-to-game basis as the number of days between current and previous games. Next, RRI was calculated as the discrepancy in rest intervals between competing teams for all games and averaged for all teams across all seasons with teams categorized by season average RRI (<-0.70; -0.7 to -0.5; -0.5 to -0.25; -0.25 to 0; 0 to 0.25; 0.25 to 0.5; 0.5 to 0.7; >0.70). Win percentage and playoff depth (lost in wild card round; lost in divisional round; lost in conference championship; lost in Super Bowl; won Super Bowl; did not make playoffs) quantified team performance. Pearson product correlations were implemented to assess the relationship between season average RRI and win percentage. One-way analyses of variance assessed differences in win percentage across RRI categories and RRI across playoff depth categories. A trivial negative correlation between RRI and win percentage across all seasons was noted. Moreover, win percentage did not differ across RRI categories, while RRI was attenuated among teams that lost in the Super Bowl and divisional round compared with teams that did not qualify for the playoffs, suggesting that RRI has no significant effect on team performance with competitive eras of NFL competition collated.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144506080","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":"Functional Training and Mat Pilates Are Effective in Improving Cardiorespiratory Capacity and Strength in People With Parkinson's Disease: A Randomized Clinical Trial With Follow-up.","authors":"Jéssica Amaro Moratelli, Clynton Lourenço Corrêa, Anelise Sonza, Adriana Coutinho de Azevedo Guimarães","doi":"10.1519/JSC.0000000000005162","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005162","url":null,"abstract":"<p><strong>Abstract: </strong>Moratelli, JA, Corrêa, CL, Sonza, A, and Guimarães, ACdA. Functional training and mat pilates are effective in improving cardiorespiratory capacity and strength in people with Parkinson's disease: a randomized clinical trial with follow-up. J Strength Cond Res XX(X): 000-000, 2025-The objective of this study was to analyze the effects of 2 12-week interventions with functional training and Mat Pilates on cardiorespiratory capacity, lower limb strength, and handgrip strength in people with Parkinson's disease, both in the short term and in the long term. Randomized clinical trial with people with Parkinson's randomized into 3 groups: functional training (n = 12), Mat Pilates (n = 11), and control group (n = 12), as well as 11 healthy individuals matched by sex and age, constituting the healthy reference group. The exercise groups received 2 60-minute sessions per week for 12 weeks. Assessments were conducted before and after the interventions with all participants and included submaximal functional capacity, handgrip strength, and lower limb muscle strength. Significance level p ≤ 0.05. In the intragroup comparison of functional training and Mat Pilates, the results indicated significant improvements in cardiorespiratory capacity and lower limb muscle strength in both the short and long terms (p < 0.001), as well as short-term improvement in right handgrip strength (p = 0.003). In the control group, a deterioration in right leg extension strength was observed in the short term and at the follow-up (p = 0.038). The study suggests that 12 weeks of functional training and Mat Pilates are effective in improving cardiorespiratory fitness, lower limb muscle strength, and right-hand handgrip strength in individuals with Parkinson's disease. These benefits are particularly relevant as they may contribute to maintaining autonomy, mobility, and quality of life in this population, reinforcing the importance of physical exercise as a complementary treatment for Parkinson's disease.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144506062","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":"Variation of Kinematic Metrics With Perceived Fatigue in Ice Skating Measured Using Wearable Sensors.","authors":"Aminreza Khandan, Ramin Fathian, Jason P Carey, Hossein Rouhani","doi":"10.1519/JSC.0000000000005181","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005181","url":null,"abstract":"<p><strong>Abstract: </strong>Khandan, A, Fathian, R, Carey, JP, and Rouhani, H. Variation of kinematic metrics with perceived fatigue in ice skating measured using wearable sensors. J Strength Cond Res XX(X): 000-000, 2025-Enabling to obtain ice skaters' kinematics, wearable technology can track skaters' performance and thus detect performance fatigue in real-world settings. Therefore, this study aimed to investigate the potential of wearable inertial measurement units (IMU) to track skaters' performance, predict perceived fatigue, and detect severe fatigue onset before serious fatigue-related sequelae. In a multistage aerobic experiment, 19 subjects, 2 groups of high- and low-caliber skaters clustered by a novel algorithm, were asked to skate at a self-selected speed around an ice rink. During the experiments, subjects skated with 2 IMUs on their dominant leg's shank and thigh and 4 IMUs on their skates, pelvis, and trunk. These IMU outputs were used to develop 22 kinematic metrics whose variations were monitored with self-reported perceived fatigue by a linear mixed model, considering the effect of caliber. Finally, a machine learning algorithm was implemented to predict severe fatigue onset using the proposed kinematic metrics. The variations of intersegment correlation, joint angle fluctuations, and trunk angle were considerable (6-17% variation) during this intermittent skating experiment. In addition, a gradient-boosting model could predict severe fatigue onset with average precision, sensitivity, accuracy, and F1 score of 75, 81, 74, and 78%, respectively, in 196 skating stages captured from the subjects. The proposed kinematic metrics, as performance indicators, could also indicate perceived fatigue during an aerobic ice skating experiment and predict severe fatigue onset. The kinematic metrics introduced in this study equip coaches with quantitative tools to monitor performance and assess perceived fatigue in ice skating.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144506081","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":"Specificity in Change of Direction Training: Impact on Performance Across Different Tests.","authors":"Michael Keiner, Konstantin Warneke, Josua Skratek, Björn Kadlubowski, Konstantin Beinert, Andreas Wittke, Klaus Wirth","doi":"10.1519/JSC.0000000000005171","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005171","url":null,"abstract":"<p><strong>Abstract: </strong>Keiner, M, Warneke, K, Skratek, J, Kadlubowski, B, Beinert, K, Wittke, A, and Wirth, K. Specificity in change of direction training: Impact on performance across different tests. J Strength Cond Res XX(X): 000-000, 2025-This study aimed to evaluate the specificity of change of direction (COD) training by investigating whether a targeted training protocol would yield superior adaptations when test and training exercises align, compared with standard soccer practice. Seventy-seven elite youth soccer players participated in a 4-arm, 4-week randomized intervention, with subjects completing 3 additional COD training sessions per week alongside their regular soccer training depending on their randomized group assignment. The training focused on either the 505, the Triangle, or the Curved Sprint COD tasks, while the control group did not receive any additional intervention. The results showed that COD training with cuts over 120° (Triangle and 505 intervention groups) led to significant (<0.05) performance improvements across all COD tests (Triangle, 505, and Curved Sprint). By contrast, the Curved Sprint intervention group improved only in the Curved Sprint test, and the control group showed no significant (p > 0.05) gains. However, sport-specific CODs vary significantly based on tactical and technical demands, making their precise definition and consequently the standardization of training challenging. Nonetheless, this study demonstrates that tailoring COD training to the specific movement requirements of the COD tests can effectively maximize performance improvements.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144258228","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 Impact of Court Orientation and Bout-Ending Mechanism on the External and Internal Loads of Female Basketball Players During Small-Sided Games.","authors":"Alejandro Rodríguez-Fernández, Enrique Flórez-Gil, Aaron Scanlan, Alejandro Vaquera","doi":"10.1519/JSC.0000000000005174","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005174","url":null,"abstract":"<p><strong>Abstract: </strong>Rodríguez-Fernández, A, Flórez-Gil, E, Scanlan, A, and Vaquera, A. The impact of court orientation and bout-ending mechanism on the external and internal loads of female basketball players during small-sided games. J Strength Cond Res XX(X): 000-000, 2025-The aims were to examine the impact of court orientation and bout-ending mechanism on external and internal loads during small-sided basketball games (SSG) in female players and examine performance-related fatigue associated with SSG formats. Twelve female basketball players participated in 4 SSG formats over a 4-week period. External (measured using local positioning system) and internal (measured using heart rate) load variables were collected. Countermovement jump and 20-m sprint were assessed pre and post each SSG. Each SSG involved 3vs3 and 3 bouts. Small-sided games formats included: (a) fixed time (3 minutes) in half-court orientation (15 × 14 m with 1 basket); (b) fixed time (3 minutes) in stretched-court orientation (7.5 × 28 m with 2 baskets); (c) fixed point (first to 5 points) in half-court orientation; and (d) fixed point (first to 5 points) in stretched-court orientation. Stretched-court SSG formats resulted in significantly greater external loads (p < 0.01, effect size [ES] = 1.89-4.42). Countermovement jump height increased (p < 0.05; ES = 0.40-0.43) across all SSG except the stretched-court fixed-point format, with 20-m sprint time unaffected across all SSG (p ≥ 0.05; ES = 0.11-0.27). Stretched-court 3vs3 SSG formats elicit greater external loads than half-court, whereas fixed-time and fixed-point bout-ending formats yield comparable demands.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144266492","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":"Reference Standards for Vertical Jump Power and Handgrip Strength for Screening the Risk of Low Bone and Muscle Mass for Age in Youth.","authors":"Fátima Baptista, Rafael Luiz de Marco, Vera Zymbal, Kathleen F Janz","doi":"10.1519/JSC.0000000000005130","DOIUrl":"https://doi.org/10.1519/JSC.0000000000005130","url":null,"abstract":"<p><strong>Abstract: </strong>Baptista, F, de Marco, RL, Zymbal, V, and Janz, KF. Reference standards for vertical jump power and handgrip strength for screening the risk of low bone and muscle mass for age in youth. J Strength Cond Res XX(X): 000-000, 2025-This study examined the predictive validity of vertical jump power and handgrip strength to discriminate at-risk youth for low muscle mass and bone mass for age. The sample consisted of 529 subjects of ages 10-18 years. Handgrip strength and vertical jump power were assessed using a hand dynamometer and a countermovement jump performed on a force platform. Dual-energy X-ray absorptiometry was used to assess lean body mass normalized for body height (kg·m-2) and bone mineral density (g·cm-2) of the whole body less head. These variables were used to determine the risk of low bone and muscle mass, defined by a Z-score ≤ -1.0 for both variables. All variables were standardized by the lambda-mu-sigma method according to sex and age group, using the sample as a reference. By sex, the analysis included the area under the curve (AUC), sensitivity (Se), and specificity (Sp). The ability to discriminate the risk of low bone and muscle mass through the assessment of musculoskeletal fitness was good to exceptional for vertical jump power (AUCs ≥0.88, Se and Sp = 78-91%) and acceptable to good for handgrip strength (AUCs = 0.75-0.88, Se and Sp = 68-73%). Risk Z-scores for musculoskeletal fitness ranged from -0.5 to -0.8, depending on the test and sex. Handgrip strength and especially vertical jump power can be used to screen the risk of pediatric low bone and muscle mass. Slight decreases in musculoskeletal fitness can be an inexpensive and noninvasive indicator of muscle and bone health.</p>","PeriodicalId":17129,"journal":{"name":"Journal of Strength and Conditioning Research","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144258227","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}