Journal of Strength and Conditioning Research最新文献

Abstract: Otremba, JR, Heesch, AJ, Morgan, RM, Poolman, MA, Schindler, GD, and Fitzgerald, JS. Bioelectrical impedance spectroscopy measures of whole and segmental skeletal muscle quantity associated with strength and power in collegiate ice hockey players. J Strength Cond Res 39(2): 242-248, 2025-Bioelectrical impedance spectroscopy (BIS) is a promising monitoring tool for body water compartment assessment, particularly intracellular water (ICW), in which acute decreases are associated with increased muscle damage and reduced function, and chronic changes are associated with muscle quantity. Because little is known about the predictive utility of BIS-derived measures in athletes, this study aimed to assess the association between whole-body and segmental compartment water measured by BIS and maximal-intensity exercise performance in athletes. Twenty-five National Collegiate Athletic Association Division I collegiate hockey players completed 2 consecutive testing sessions. Body water and composition were assessed using a SOZO BIS device. Strength and explosive strength were measured on a force platform during the isometric belt squat and squat jump, respectively. Peak power was assessed using the 6-Second Test on a Wattbike. Pearson's r and partial correlation were used to assess relationships. Select body water and composition BIS variables were strong correlates of strength ( r = 0.51-0.63, p < 0.05), moderate correlates of power ( r = 0.41-0.44, p < 0.05), and lacked association with explosive strength. Segmental leg variables tended to be the strongest correlates of strength and power. Body water and traditional lean mass variables expressed similar predictive utility. Intracellular water/extracellular water lacked associated with exercise performance in bivariate and adjusted models. We provide evidence of the criterion validity of whole-body (i.e., ICW, fat-free mass, skeletal muscle mass [SMM]) and segmental (i.e., leg ICW, leg SMM) BIS variables, related to the quantity of SMM, to predict body-size dependent maximal-intensity exercise performance. Practitioners can use this information to determine which variables to track for performance readiness monitoring.

Abstract: Marins, EF, de Araújo Rocha Junior, V, Castagna de Freitas, F, Rossy e Vasconcelos Júnior, J, Aparecido Minervi, N, Dawes, JJ, and Boscolo Del Vecchio, F. Unraveling the boundaries of police physical fitness: normative values of police physical fitness based on a representative sample of 8000 federal highway police officers aged 21-70 years from Brazil. J Strength Cond Res 39(2): 260-268, 2025-To develop age- and sex-based normative tables related to physical fitness components (cardiorespiratory fitness, muscular endurance, and power) from a representative sample of the Brazilian police population. This analysis included archived data from 8,628 police officers evaluated in 4 physical fitness tests (PFTs) conducted in 2020. Cardiorespiratory fitness was assessed by a 12-minute run test, endurance by the 60-s sit-up and push-up tests, and lower-limb muscular power by standing broad jump test. Additive quantile regression was used to determine percentiles and estimate age-based charts for each test by sex. Reference values were described from these data. Significant differences between sexes for all measures of physical fitness ( p < 0.01, d = 0.14-1.68), except for upper-limb endurance, were observed ( p > 0.05, d = 0.05). There was a decline in performance in all measures of physical fitness among police officers of both sexes with advancing age categories, with younger groups performing better than older groups ( p < 0.05, d = 0.27-3.17). Age charts and curves were created using the output of quantile regression of reference values for cardiorespiratory fitness, abdominal and upper-limb endurance, and lower-limb power corresponding to the 10th, 20th, 40th, 60th, 80th, and 90th percentiles at all ages, for both sexes. Classificatory tables were presented by age and sex, with reference values for the tests using percentile values. Lower levels of physical fitness were observed with aging, and men exhibited higher overall values than women. The reference values presented can serve as a guide for interpreting the results of PFTs obtained by other police institutions and developing training programs to enhance health, fitness, and performance.

Abstract: Bordelon, NM, Agee, TW, Wasserberger, KW, Downs-Talmage, JL, Everhart, KM, and Oliver, GD. Field-testing measures related to youth baseball hitting performance. J Strength Cond Res 39(2): 210-216, 2025-The purpose of the study was to determine the relationship between field tests and youth hitting performance (batted-ball velocity). Forty-nine youth baseball athletes (age: 11.1 ± 1.6 years; height: 151.7 ± 13.2 cm; body mass: 47.1 ± 15.1 kg) were rotated through the following field tests: passive bilateral hip and shoulder internal rotation (IR) and external rotation (ER) range of motion (ROM), bilateral hip and shoulder ER and IR isometric (ISO) strength, bilateral grip strength, trunk rotation ROM, standing broad jump (SBJ), triple broad jump, single leg lateral rotational jumps, and 3 maximal effort hits off a stationary tee. Regression analyses were performed to determine the associations between grip strength, hip strength, jump tests, and ROM with batted ball velocity. For the grip strength, hip strength, and jump tests regression models, body mass (kg) and height (cm) were entered first to estimate the proportion of variance accounted for by anthropometrics. A Bonferroni correction was applied a priori to α = 0.013. The jump-testing model, including only SBJ distance, was the best predictor of batted ball velocity above and beyond the predictive effects of anthropometric measures. Although less than the jump-testing model, the results determined that the hip strength model, including only nondominant hip ER ISO strength, was the second-best predictor of batted ball velocity. Practitioners can use these tests to monitor training progression in youth baseball athletes and identify deficits in physical ability that can be improved.

Abstract: King, BW, Snow, TK, and Millard-Stafford, M. Peak lower-extremity power unadjusted for body mass predicts fastball velocity in collegiate baseball pitchers. J Strength Cond Res 39(2): 217-226, 2025-The relationship between lower-extremity power production and fastball velocity in collegiate pitchers remains unclear. This study aimed to evaluate the relationship between lower-extremity power and throwing velocity in 33 National Collegiate Athletic Association Division I baseball pitchers. Lower-extremity power was quantified using countermovement jump (CMJ) testing on force plates and the Wingate anaerobic cycling test. In-game fastball velocities were collected using TrackMan technology. Pearson correlations and linear regressions were used to evaluate the association between lower-body power and fastball velocity. The strongest predictor of peak fastball velocity was body mass ( r = 0.58, p = 0.0004), followed by lean mass ( r = 0.52, p = 0.002). Peak power (W) produced on the Wingate and CMJ tests were each statistically significant predictors of peak velocity ( r = 0.44, p = 0.011; r = 0.43, p = 0.014, respectively), but CMJ power relative to body mass ( r = 0.19), jump height ( r = 0.07), and Sparta Scores ( r = -0.06) were not ( p > 0.05). Linear regression indicated Wingate and CMJ absolute peak power tests each independently explained 19% of the variance in fastball velocity but added little to the model when combined with body mass (∼34 vs. 32% of total variance). Because total body mass and lower-body power are important predictors of pitching velocity, absolute power output is a more relevant predictor of baseball pitching velocity than lower-body power variables influenced by body mass (e.g., jump height and Sparta Score).

Abstract: Suchomel, TJ, Kissick, CR, Techmanski, BS, Mann, JB, and Comfort, P. Velocity-based training with weightlifting derivatives: Barbell and system velocity comparisons. J Strength Cond Res 39(2): 135-146, 2025-The aim of this study was to examine the differences in barbell and system (i.e., subject + load) velocity during weightlifting derivatives performed across a spectrum of relative loads. 14 resistance-trained men participated in 6 testing sessions, which included 1 repetition maximum hang power clean (HPC) testing and individual jump shrug (JS), hang high pull (HHP), HPC, hang clean pull (HCP), and countermovement shrug (CMS) sessions. The order of the exercise testing sessions was randomized and required the subjects to perform either JS, HHP, HPC, HCP, or CMS repetitions while standing on a force platform with a linear position transducer attached to the barbell. The JS and HHP were performed with 20, 40, 60, 80, and 100% of their 1 repetition maximum HPC, HPC with 20, 40, 60, and 80% 1RM, and the HCP and CMS performed with 20, 40, 60, 80, 100, 120, and 140% 1RM. Mean and peak barbell and system velocities were determined across all exercises and loads using either 2 × 5, 2 × 4, or 2 × 7 repeated measures ANOVA depending on the number of loads performed. Significantly ( p < 0.001) and meaningfully ( g ≥ 1.49) greater mean and peak barbell velocities existed at every exercise and load combination compared with the mean and peak system velocities produced. Barbell and system velocity are distinct characteristics that should not be substituted for one another. Owing to the characteristics of the transition phase, mean barbell and system velocity may not provide strength and conditioning practitioners with meaningful information related to load prescription.

Abstract: Kuhlman, NM, Jagim, AR, Jones, MT, Feit, MK, and Fields, JB. A comparison of match external load demands across women's collegiate field sports. J Strength Cond Res 39(2): 234-241, 2025-Historically, soccer (SOC), lacrosse (LAX), and field hockey (FH) have been grouped together as "field sports" due to their intermittent nature of match play and similar physiological demands. However, questions have emerged regarding potential variations in demands between sports. The purpose of this study was to compare external match workloads between collegiate women's SOC, LAX, and FH, and examine within-sport positional differences. Athletes (SOC: n = 15; LAX: n = 15; FH: n = 14) wore a global positioning system device during all matches throughout a competitive season. External load metrics included in the analysis were total distance (TD), sprint distance (SD), accelerations (>3 m·s -2 ), sprint efforts (SE), player load (PL), PL per minute (PL/min), top speed (m·s -1 ), and distances covered in select speed zones. Soccer performed higher external load volumes (TD, PL) ( p ≤ 0.025) but incurred lower intensities (SD, SE, accelerations) ( p < 0.001) compared with LAX and FH. Within-sport positional differences were apparent in SOC ( p < 0.001-0.018), LAX ( p < 0.001-0.045), and FH ( p < 0.001-0.004). However, FH exhibited more positional variance in external load metrics compared with SOC or LAX. Field hockey midfielders covered greater volumes (TD, PL) compared with attackers and defenders ( p < 0.001), while attackers sustained greater intensities (SD, SE, top speed) compared with midfielders and defenders ( p < 0.004). Results indicate that there are significant differences in external workload parameters between sports and across positions. Practitioners should tailor sport-specific and position-specific programs to match demands, and future research should explore the proposed categorizations of LAX as a "fast collision invasion sport," FH as a "fast contact invasion sport," and SOC as a "slow contact invasion sport."

Abstract: Padrón-Cabo, A, Lorenzo-Martínez, M, De Dios-Álvarez, V, Rey, E, and Solleiro-Durán, D. Effects of a short-term detraining period on the physical fitness in elite youth soccer players: a comparison between chronological age groups. J Strength Cond Res 39(2): e149-e154, 2025-The aim of this study was to examine the effects of a 2-week in-season training cessation on neuromuscular and endurance performance in 2 different age groups of elite youth soccer players. A total of 30 players belonging to the under-15 (U15, n = 17) and under-17 (U17, n = 13) age groups of a Spanish professional soccer academy participated in the study. The following tests were assessed before and after the training cessation period: squat jump (SJ), countermovement jump (CMJ), 20-m sprint with 5-m and 10-m split times, modified 505 change of direction, and 30-15 Intermittent Fitness Test (30-15 IFT). The results showed significant and similar performance impairments between the 2 age groups in SJ ( p = 0.020), CMJ ( p = 0.044), 20-m sprint ( p < 0.001), and 30-15 IFT ( p < 0.001). The U17 players evidenced greater impairment than the U15 players in 5-m ( p = 0.006) and 10-m ( p = 0.002) sprint performance. However, there was no significant change ( p = 0.070) in the players' change of direction performance. These findings provide valuable information for strength and conditioning coaches, suggesting the need for targeted interventions to mitigate the effects of detraining on neuromuscular and endurance performance during short-term in-season training cessation periods in elite youth soccer players. Special attention should be paid to maintaining sprint performance during short-term detraining periods in U17 players.

Abstract: Faricier, R, Fleitas-Paniagua, PR, Iannetta, D, Millet, GY, Keir, DA, and Murias, JM. Time spent near maximal oxygen uptake during exercise at different regions of the severe-intensity domain. J Strength Cond Res 39(2): e106-e114, 2025-This study applied the critical power (CP) model and several bouts of constant-power exercise within different regions of the severe-intensity domain to determine whether there exists an optimal intensity to maximize time spent near V̇ o2 peak. Subjects visited the laboratory 9 times. After a ramp-incremental test to determine V̇ o2 peak and peak power output (PO peak ), 9 active individuals (5 females) performed 4 constant-power bouts to task failure between 65 and 100%PO peak to estimate CP and total finite work above CP (W'). Subjects then completed 4 additional exhaustive trials predicted to result in task failure in ∼3, 6, 9, and 12 minutes. Time spent at V̇ o2 peak was calculated as the duration at which V̇ o2 ≥ 95% of the trial-specific V̇ o2 peak. The level of significance set for the study was p < 0.05. Mean CP and W' were 201 ± 48 W and 17.6 ± 8.4 kJ, respectively. For each bout, time to task failure was 2.7 ± 0.5, 6.3 ± 0.6, 9.5 ± 1.2, and 13.1 ± 3.1 minutes for the 3-, 6-, 9-, and 12-minute conditions. Time spent at V̇ o2 peak during the 3-minute trial (45 ± 22 seconds) was shorter than during the 9-minute (204 ± 104 seconds; p = 0.002) and 12-minute trials (260 ± 155 seconds; p < 0.001). The 6-minute trial (117 ± 46 seconds) had shorter ( p = 0.005) time spent at V̇ o2 peak compared with the 12-minute trial. At least when performing single bouts of exercise, intensities closer to CP (i.e., those sustainable for ∼9 minutes or longer) seem preferable compared with POs in the upper regions of the severe-intensity domain to maximize time at V̇ o2 peak.

Abstract: Bishop, C. Using ratio data in strength and conditioning: component parts hold the key. J Strength Cond Res 39(2): e176-e179, 2025-In strength and conditioning, ratio data are made up of more than 1 component part and are now commonplace in both research and practice, with an abundance of metrics from strength and jump testing being used as part of the ongoing monitoring process. Given these data have been used for many years, their inherent issues may not be obvious to all practitioners. However, ratio data often exhibit greater measurement error than their individual component parts. In addition, monitoring alterations in ratio data also presents challenges, given there is more than 1 way that the resultant test score can change. This brief review provides some practical examples to illustrate these challenges but also some viable solutions to guide practitioners on how the concurrent monitoring of ratios and their component parts can help guide decision-making in day-to-day practice.

Abstract: Modric, T, Clemente, FM, Versic, S, Chmura, P, Andrzejewski, M, Kryściak, J, and Sekulic, D. Environmental heat stress detrimentally affects match running performance of elite soccer teams competing in the UEFA Champions League. J Strength Cond Res 39(2): e142-e148, 2025-This study aimed to examine the effect of environmental heat stress (EHS), defined by wet-bulb globe temperature (WBGT), on match running performance (MRP) while controlling for match-related contextual factors. For this purpose, 2 approaches were implemented: (a) the MRP in heat stress nonrisking environment (NoEHS) (WBGT <22° C) and heat stress risking environment (EHSrisk) (WBGT ≥22° C) were compared and (b) changes in MRP according to the 1° C increase in WBGT were evaluated. Data on MRP were collected using an optical tracking system from all teams ( n = 32) in all UEFA Champions League matches ( n = 125) during the 2022-23 season. Metrics included total distance (TD), low-intensity (LIR), moderate-intensity (MIR), and high-intensity running (HIR) distances. Results indicated that less TD (108.84 vs. 110.71 km; Cohen's d [ d ] = 0.53), MIR (15.91 vs. 17.09 km; d = 0.85), and HIR (8.75 vs. 9.23 km; d = 0.46) were covered in matches played in EHSrisk compared with the NoEHS. Further investigation indicated that for every 1° C increase in WBGT, TD averagely decreased by 0.16 km ( d = -0.48), MIR by 0.13 km ( d = -1.09), and HIR by 0.06 km ( d = -0.69). These findings demonstrated decreased overall and intensive workload during the matches in EHSrisk, suggesting the detrimental effect of EHS on match volume and intensity in elite soccer. When EHS risk is anticipated, consideration of playing and recovery strategies should be implemented by coaches to achieve tactical goals while minimizing physical strain during a match.