Journal of Strength and Conditioning Research最新文献

Abstract: Kissick, CR, Techmanski, BS, Comfort, P, and Suchomel, TJ. The reliability, bias, differences, and agreement between velocity measurement devices during the hang clean pull. J Strength Cond Res 39(3): 289-294, 2025-This study examined the reliability, bias, differences, and agreement between the GymAware PowerTool (GA) and Tendo Power Analyzer (TENDO) during the hang clean pull (HCP). Fourteen resistance-trained men performed HCP repetitions with 20, 40, 60, 80, 100, 120, and 140% of their 1 repetition maximum hang power clean (1RM HPC) with GA and TENDO devices attached to the barbell. Least-products regression was used to examine instances of proportional and fixed bias for mean barbell velocity (MBV) and peak barbell velocity (PBV) between devices. In addition, Hedge's g effect sizes were calculated to determine the magnitude of the differences between devices. Excellent reliability was displayed by the GA for all measurements. While excellent reliability for the TENDO was displayed for MBV across all loads, only moderate-good reliability was present for PBV at loads >80% 1RM. The TENDO displayed proportional bias for both MBV and PBV as well as fixed bias for PBV at 140% 1RM compared with the GA. Despite the small effect sizes that existed between devices for both MBV ( g = 0.35-0.57) and PBV ( g = 0.23-0.54), none of these differences were practically meaningful. The GA and TENDO are reliable devices that can measure MBV and PBV accurately during the HCP; however, practitioners should note that the TENDO may overestimate MBV and PBV to a small extent (3.7-6.8% and 1.8-2.9%).

Abstract: Geneau, MC, Carey, DL, Gastin, PB, Robertson, S, and James, LP. Replicability of strength domains in Australian rules football athletes. J Strength Cond Res 39(3): e451-e457, 2025-Maximal lower body strength is a multidimensional construct defined as the maximum force application under specific task constraints. It is crucial for many athletic tasks and is frequently assessed in strength and conditioning environments. Recent technological advancements have increased the number of measurement options for lower body strength, making data interpretation and translation challenging. Principal component analyses (PCA) methods have been proposed to inform strength test and metric selection in field sport athletes, but these methods are limited to cross-sectional designs. This study aimed to investigated the replicability of a PCA method for metric reduction and selection at 2 time points. Thirty-three Australian rules football athletes completed 7 lower body extensor strength tests during preseason (T1) and end of season (T2), each resulting in 280 force-time metrics. At each time point, 9 PCA components were required to explain at least 70% of the variance in the data set, and 7 components demonstrated similar metric loadings onto the components. However, the variable selection procedure did not return the exact same set of variables at both time points. These results suggest that while the number and loading of strength domains are consistent in Australian rules football athletes, the variable selection procedure was not fully replicable. Overall, practitioners can use this information to select tests and metrics within the domains and subdomains identified in this study to capture a range of lower body strength information from their athletes.

Abstract: Van Roie, E, van Uffelen, J, and Delecluse, C. Stair-climbing versus machine-based resistance exercise to improve muscle power among older adults: a non-inferiority trial. J Strength Cond Res 39(3): e496-e505, 2025-Machine-based resistance training (RT) can reduce the age-related loss in muscle power ( Pmax ). However, weight-bearing exercises have greater potential for implementation. This study investigated whether stair-climbing exercise (STAIR) was non-inferior to improve Pmax compared with machine-based RT among older adults. Functional capacity tests were secondary outcomes. Older adults (30♂ and 16♀; 70.9 ± 4.3 years) were randomly assigned to RT or STAIR ( n = 23 per group). Supervised laboratory-based training sessions were performed 2 times per week for 12 weeks. In week 1-4, exercises were performed at controlled speed (hypertrophy-oriented; 4 × 12-15 repetitions; 55% of 1 repetition maximum (1RM) in RT; step-up exercise with height of 30-40 cm in STAIR), in week 5-12 as fast as possible (power-oriented, 4 × 12 repetitions; 40% of 1RM for RT and 4 × 2 flights of 6 steps for STAIR). Leg-extensor Pmax and functional capacity were measured pre-intervention and post-intervention, and Pmax also after 4 weeks of training. Gains in Pmax were not statistically different in RT (19.5 ± 12.2%) and STAIR (13.7 ± 16.5%) ( d = 0.39, pint = 0.086), whereas non-inferiority analyses were inconclusive (between-group difference in gains: 5.8% (95% CI -3.1 to 14.6); non-inferiority limit 3.9%). STAIR increased more in stair ascent performance ( d = 0.45-0.61, pint < 0.05) than RT. STAIR and RT improved similarly on 10-m fast walk, 5-repetition sit-to-stand, and countermovement jump ( pint > 0.05). To conclude, STAIR and RT both induced significant changes in Pmax and functional capacity in older adults. STAIR was beneficial over RT for gains in stair-climbing performance. Future research should investigate the effects of STAIR in a home-based unsupervised setting.

Abstract: Gundersen, AH, van den Tillaar, R, Falch, HN, Fredriksen, AB, and Larsen, S. A biomechanical comparison between conventional, sumo, and hex-bar deadlifts among resistance trained women. J Strength Cond Res 39(3): 281-288, 2025-The deadlift is a multijoint exercise frequently used to strengthen the lower extremities and spinal erectors. Despite variations, such as the conventional, sumo, and hex-bar deadlifts, little is known about how these techniques affect the concentric phase of maximal deadlifts among strength trained women. Therefore, this study used statistical parametric mapping to compare kinematics, net joint moments (NJMs), and surface electromyography amplitude between these deadlift variations during the last repetition of a 3 repetition maximum (3RM) in strength trained women. Eleven women (body mass: 67.64 ± 7.27 kg, height: 161.91 ± 3.05 cm, age: 23.18 ± 3.46 years) performed 3RM deadlifts in conventional, sumo, and hex-bar deadlifts, lifting 103.18 ± 18.47, 101.54 ± 15.01, and 99.70 ± 15.94 kg, respectively. The main findings showed that deadlifting with conventional and sumo techniques resulted in larger hip NJMs near the lockout. Conversely, deadlifting with the hex-bar technique resulted in greater barbell velocity, knee NJMs, and increased hip and knee flexion angles. Therefore, when training maximal 3RM deadlifts, we suggest that hex-bar deadlifts may be beneficial for targeting knee extensors and enhancing barbell velocity among strength trained women. Conversely, sumo and conventional deadlifts may be more effective for targeting the hip extensors near the lockout during the last repetition of 3RM deadlifts.

Abstract: Hirsch, SM, Chapman, CJ, Singh, H, Baker, DG, and Frost, DM. A critical appraisal of using barbell velocity data to regulate training. J Strength Cond Res 39(3): 360-372, 2025-Practitioners must balance numerous training variables to ensure they do not impose too much nor too little training stress on their athlete. As an athlete's capacity can fluctuate based on their preparedness for training, the intended vs. actual training intensity in a fixed training program may not coincide. Similarly, the training set volume that an athlete should be exposed to may fluctuate depending on their current state. A discrepancy between intended vs. actual training intensity and volume could negatively impact subsequent training adaptations. Thus, researchers and practitioners have advocated for "autoregulation," whereby the volume and intensity of training are automatically adjusted based on the athlete's preparedness. One proposed method of autoregulating resistance training is by using barbell velocity data. However, it is unclear whether, and under which contexts, these data are appropriate for regulating resistance training. Therefore, the purpose of this literature review was to critically examine the current research on using barbell velocity data to regulate resistance training intensity and volume. After examining the relevant literature, it is the authors' belief that the current data do not support using velocity data to precisely regulate resistance training intensity. However, it is the authors' belief that the current literature does suggest that researchers and practitioners can leverage these data to regulate other aspects of resistance training, such as athlete motivation, autonomy, and focus of attention, which could also impact the resulting adaptations from training. Overall, more research is required to better understand how researchers and practitioners should use velocity data to guide training.

Abstract: García-Sánchez, C, Jiménez-Ormeño, E, Lominchar-Ramos, JM, Giráldez-Costas, V, McMahon, JJ, and Soriano, MA. Effects of a short-term detraining period on neuromuscular performance in female handball players. J Strength Cond Res 39(3): e469-e477, 2025-The aim of this study was to determine the effects of a 3-week detraining period on lower limbs' neuromuscular performance in female handball players. Fourteen semi-professional players (age: 20.50 ± 2.98 years; height: 1.67 ± 0.06 m; body mass: 66.89 ± 8.75 kg) were evaluated using force plates on 3 separate occasions to assess the maximum and rapid force production by the isometric mid-thigh pull (IMTP) and the ballistic capabilities by countermovement jump (CMJ). The intraclass correlation coefficient, coefficient of variation, standard error of the measurement, and smallest detectable difference were calculated using the first 2 testing sessions. Pre- and postdetraining differences were calculated comparing the first and third testing sessions, using paired t -tests or Wilcoxon test when appropriate and Hedges g effect sizes (ES). The level of significance was set at ρ ≤ 0.05. There were no significant or meaningful differences in maximum and rapid force production capabilities assessed during the IMTP ( p > 0.05). However, there was a significant detriment with small ES in CMJ jump height, modified reactive strength index, peak and mean propulsive force, peak and mean braking force, and braking phase duration ( p < 0.05). These findings suggest that although maximum and rapid force production capabilities were not altered among female handball players after a 3-week detraining period, their ballistic capabilities decreased, especially those affecting the eccentric part of a fast dynamic task. They also highlight the importance of testing, planning, and programming in response to the fluctuations in handball players' physical performance over the season.

Abstract: Polletta, J, Leung, K, Diaz, D, Branum, N, and Mokha, M. Influence of interlimb lean muscle mass asymmetry on countermovement jump neuromuscular performance qualities among American football players. J Strength Cond Res 39(3): 325-331, 2025-Body composition is a determinant of athletic performance. The purpose of this study was to determine the influence of lower limb lean muscle mass (LMM) asymmetry on countermovement jump (CMJ) performance and kinetic asymmetry during both eccentric and concentric CMJ phases. Seventy-four American football players (age, 23.0 ± 0.9 years; height, 1.86 ± 0.07 m; mass, 104.9 ± 21.6 kg; lean body mass, 88.7 ± 12.5 kg) training for the 2024 National Football League draft underwent body composition assessment using an InBody 270 bioelectrical impedance analyzer that yielded right and left leg LMM in kg. Subjects then performed 3 CMJs on dual uniaxial force plates that allowed for the calculation of jump height (JH), reactive strength index modified (RSImod), and interlimb percentage asymmetry of peak force and impulse for eccentric and concentric phases. A paired t -test and Pearson Product-moment Correlation Coefficients calculated the difference between left and right LMM and the associations between the symmetry variables, respectively, p ≤ 0.05. Right and left leg LMM were significantly different (t(73) = 3.772, p ≤ 0.001). However, no significant relationships were found between lower limb LMM asymmetry (0.67 ± 0.67%) and any asymmetry in CMJ eccentric peak force (4.77 ± 3.75%), r (72) = 0.001, p = 0.954; eccentric deceleration impulse (5.23 ± 4.36%), r (72) = 0.158, p = 0.180; concentric peak force (2.99 ± 2.54%), r (72) = -0.70, p = 0.553; concentric impulse (3.06 ± 2.97%), r (72) = 111, p = 0.347; JH (41.8 ± 7.3 cm), r (72) = -0.205, p = 0.08; or RSImod (0.53 ± 0.14 m·s -1 ), r (72) = -0.151, p = 0.199. The magnitude of LMM asymmetry did not influence CMJ performance or asymmetry magnitude. Reducing CMJ kinetic asymmetry may require targeted programming, especially for the eccentric loading phase.

Abstract: De Bleecker, C, Vermeulen, S, Willems, T, Segers, V, Spanhove, V, Leys, R, Vanrenterghem, J, and De Ridder, R. Validation of impact forces estimated by wearable device VERT in volleyball validation impact forces VERT. J Strength Cond Res 39(3): e458-e462, 2025-As volleyball players are exposed to high volumes of forceful jump-landing actions, the risk of injuries is increased. Wearable technology such as the VERT device offers a promising avenue for load monitoring of volleyball players, potentially allowing better control of intensity of training and matches to minimize the likelihood of injuries. Although validity of jump counts and jump height is well investigated, studies validating impact forces estimated by VERT device referenced to force plate data are scarce. The objective of this study was to validate the use of VERT for the estimation of impact forces during volleyball. Twenty-one volleyball players of different levels performed countermovement jumps (CMJ), block jumps, spike jumps, and a set with a combination of several volleyball jump-landing tasks. Impact forces estimated by VERT were compared with resultant force values measured using a force plate. A total of 221 spike jumps, 286 block jumps, and 203 CMJ were analyzed. Given the identified proportional bias and heteroscedasticity, an adapted Bland-Altman plot featuring the line of best fit and V-shaped 95% confidence intervals instead of classic limits of agreement was created. Furthermore, our results suggest a proportional bias between the 2 measurements, with the VERT sensor tending to overestimate impact forces compared with the force plate, increasingly at higher mean values. Therefore, the VERT algorithm has not been proven valid for quantifying impact forces. However, a correction factor is proposed to obtain better results for impact forces estimated by VERT, making it suitable for implementation in sport contexts.