Journal of Strength and Conditioning Research最新文献

Abstract: Grammenou, M, Kendall, KL, Wilson, CJ, Porter, T, Laws, SM, and Haff, GG. Effect of fitness level on time course of recovery after acute strength and high-intensity interval training. J Strength Cond Res 38(12): 2055-2064, 2024-The aim was to investigate time course of recovery after acute bouts of strength (STR) and high-intensity interval training (HIIT). A secondary goal was to assess the influence of total fitness score (TFS), composed of handgrip strength and maximum aerobic power on recovery. Twenty-eight resistance-trained individuals completed 8 testing sessions within a 14- to 17-day period. Subjects performed a testing battery comprising isometric midthigh pull (IMTP), countermovement jump (CMJ), and a modified Wingate test (WINmod) at baseline, immediately after exercise, as well as at 6 and 24 hours after the training sessions. A one-way ANOVA was performed to examine time changes after the training sessions. Subjects were then grouped based on their TFS in high, medium, and low groups. To examine the influence of TFS on time course of recovery, we performed a linear mixed-effects model. Statistical significance was set at p < 0.05. Both training sessions resulted in a significant reduction in peak force (PF) that persisted for up to 6 (p < 0.05) and 24 hours (p < 0.001). The STR session showed immediate and 24-hour postexercise declines in jump height and reactive strength index modified (RSImod) compared with baseline. The low TFS group exhibited a significant RSImod reduction immediately after HIIT (p < 0.001), compared with the medium TFS group (p = 0.0002). In the STR session, the high TFS group displayed an increased eccentric displacement during CMJ 24 hours after exercise compared with baseline (p = 0.033). Overall, subjects with high TFS may be able to recover CMJ performance at the same rate as other TFS groups, despite performing more work.

Abstract: Philipp, NM, Blackburn, SD, Cabarkapa, D, and Fry, AC. The effects of a low-volume, high-intensity pre-season micro-cycle on neuromuscular performance in collegiate female basketball players. J Strength Cond Res 38(12): 2136-2146, 2024-The use of stretch-shortening cycle (SSC)-based measures of vertical jump performance to monitor responses to training exposures is common practice in sport science. However, evidence is limited with regards to which assessments and metrics may be most sensitive toward changes in training volume and intensity. The aim of this study was to investigate how a reduction in training volume, paralleled with an increase in training intensity, affects neuromuscular performance as measured through a countermovement jump (CMJ) and 10-5 hop test over a preseason period in female collegiate basketball players. Over a 3-week baseline period, athletes completed CMJ and 10-5 hop tests to quantify baseline performance. Measures of neuromuscular response to the changes in training volume and intensity were performed 2 and 4 days into the intervention week, as well as post 72 hours, post 7 days, and post 10 days. External workload data and descriptive analyses of resistance training stimuli suggest that during the intervention week, athletes experienced significantly lower training volumes and increases in training intensity. In response to these changes in training stimulus, athletes showed depressed performance acutely in metrics derived from both the CMJ and 10-5 hop test. Authors also observed a supercompensation effect at post 72 h, post one week, and post 2 weeks for metrics related to lower-limb stiffness and braking rate of force development. These findings highlight that in response to a high-intensity, low-volume training phase, female basketball players experienced alterations in lower-limb function, reflected in both decreases and increases in SSC performance.

Abstract: Poulios, A, Fotiou, C, Draganidis, D, Avloniti, A, Rosvoglou, A, Batrakoulis, A, Tsimeas, P, Papanikolaou, K, Deli, CK, Stampoulis, T, Douroudos, II, Chatzinikolaou, A, Jamurtas, AZ, and Fatouros, IG. The energy expenditure associated with body-weight resistance exercises of various movement patterns performed at different durations. J Strength Cond Res 38(12): 2034-2046, 2024-Although body-weight resistance exercises (BWRE) are popular and effective for body mass reduction and neuromuscular performance, limited information exists regarding their total energy expenditure (TEE). This study determined the energy cost associated with seven BWRE of different movement patterns plank, push-ups, squat, single-leg squat [SLS], forward lunge [FL], burpees, and jumping jacks [JJ] using 2 different durations (T30: 30-second; T45: 45-second) in 10 healthy young adults using a randomized, 2-trial, crossover, repeated-measures design. The level of significance was set at p ≤ 0.05. The burpees were associated with the highest and the plank with the lowest intensity (rates of perceived exertion [RPE] and mean heart rate [MHR]) and metabolic load (blood lactate [BL] accumulation, metabolic equivalents of task [METs], and excess post-exercise oxygen consumption [EPOC]) in both trials. In T30 and T45, TEE (kcals per minute) was 11.3/12.6 in plank, 18.6/22.0 in FL, 19.8/21.2 in SLS, 19.9/23.2 in squat, 22.0/24.9 in push-ups, 23.1/22.8 in JJ, and 32.2/40.7 in burpees. Although RPE, MHR, BL, and EPOC were comparable among T30 and T45, METs and TEE were greater in T45. These results suggest that TEE of BWRE ranges from ∼11 to 40 kcals·min -1 , depending on the movement pattern and the duration of exercise. This information may be valuable for those using BWRE for body-weight management and improvement of strength performance.

Abstract: Kadlec, D, Jordan, MJ, Alderson, J, and Nimphius, S. Examining the effects of dynamic and isometric resistance training on knee joint kinetics during unplanned sidesteps in elite female athletes. J Strength Cond Res 38(12): 2079-2087, 2024-The purpose of this study was to examine the effects of a 4-week block of isometric (isometric RT ) and dynamic resistance training (dynamic RT ) on kinetic variables associated with anterior cruciate ligament (ACL) injury risk during unplanned sidesteps in elite female athletes. Twenty-one elite female athletes competing for a women's international rugby union team were recruited with 15 ( n = 15; age: 23.4 ± 4.7 years; 170.7 ± 8.4 cm; 84.4 ± 15.4 kg) completing assessment of knee flexion moment, knee valgus moment (KVM), knee internal rotation moment (KIRM), knee joint power during unplanned sidesteps, and lower limb strength before and after a 4-week intervention. Linear mixed effects models and one-dimensional statistical parametric mapping assessed the effect of the interventions. Statistical significance was set at α = 0.05. Postintervention the isometric RT group revealed reduced peak KVM during early stance ( p = 0.04) while the dynamic RT group decreased peak KIRM ( p < 0.01) and KIRM over 8.8-86.6% ( p < 0.01) and 96.9-98.5% ( p = 0.047). An exploratory combined group analysis revealed reductions in KVM over 7.9-21.8% ( p = 0.002) and in KIRM over 8.3-90.5% ( p < 0.01) and 96.2-98.5% ( p = 0.046). Most lower limb isometric and dynamic strength measures increased after both resistance training interventions. Overall, both groups increased lower-body maximum strength while reducing kinetic knee joint variables associated with ACL injury risk during unplanned sidesteps. These results highlight the importance of increasing single-joint and multijoint strength in female athletes to mitigate the mechanical knee joint demands during sidestepping.

Abstract: Hammert, WB, Dankel, SJ, Kataoka, R, Yamada, Y, Kassiano, W, Song, JS, and Loenneke, JP. Methodological considerations when studying resistance-trained populations: Ideas for using control groups. J Strength Cond Res 38(12): 2164-2171, 2024-The applicability of training effects from experimental research depends on the ability to quantify the degree of measurement error accurately over time, which can be accounted for by including a time-matched nonexercise control group. Yet, control groups are rarely included in studies on resistance-trained individuals. Many authors instead report short-term relative or absolute measures of reliability for the interpretation of statistical tests and the size or meaning of effects observed and assume that good short-term reliability justifies the lack of a control group. In this article, we offer some potential alternatives for employing control groups in research studies on resistance-trained individuals. We wish to suggest researchers consider using a "time-matched training group" (i.e., resistance-trained individuals who keep an exercise log, continue their normal training, and perform the pre- and posttest measures spanning the same duration as that of the exercise group or groups) and/or a time-matched nonexercise control group (i.e., non-resistance-trained individuals who perform only the pre- and posttest measures spanning the same duration as that of the exercise training group or groups). If it is not feasible (e.g., researchers do not wish to randomly assign individuals to a time-matched training group or include a time-matched nonexercise control group) to employ such designs, or relevant, then an alternative approach might be to include a run-in (i.e., control) period that spans the same duration as the exercise training intervention. Our hope is that this article can help strengthen future research designs conducted on resistance-trained individuals.

Abstract: García-Sánchez, C, Navarro, RM, Nieto-Acevedo, R, and de la Rubia, A. Is match playing time a potential tool for managing load in women's handball? J Strength Cond Res 38(12): e769-e775, 2024-The aim of this study was to explore the external load experienced by female handball players according to the time played in official matches (≥40, <40, and ≤20 minutes) and in relation to playing positions (backs, pivots, and wings). Twenty-two female players from the Spanish second Division were monitored across 13 matches. Total distance covered, high-speed running distance (HSR), accelerations, decelerations, and PlayerLoad were collected in absolute and relative values using a local positioning system (WIMU PRO, Realtrack Systems SL, Almería, Spain). One-way ANOVA with partial eta-squared and Cohen's d were used to determine the differences between playing time groups and between playing positions. This study revealed that players with more match playing time had a higher absolute values in all external load variables ( p < 0.001; very large effects), except in HSR where only wings showed higher values according to the time played ( p < 0.001; very large effects). However, these differences between playing time groups disappear when the external load values were normalized according to the effective playing time ( p > 0.05). In relation to playing positions, wings covered more HSR/minutes than the other playing positions regardless of the playing time ( p < 0.05; large effects). In addition, backs performed more ACC/minutes than wings in the high playing time group and more than pivots in the low playing time group ( p < 0.05, moderate effects). In addition, backs performed more DEC/minutes than wings in the low playing time group ( p < 0.05, moderate effects). Therefore, handball coaches should consider the playing time as an effective tool to optimize the weekly load distribution.

Abstract: Benjaminse, A, Nijmeijer, EM, Gokeler, A, Broekhaar, DC, and Cortes, N. Motivation unraveled: giving choice to football players to improve anterior cruciate ligament injury prevention. J Strength Cond Res 38(12): e735-e743, 2024-Providing athletes some control over a training session facilitates motor skill acquisition. This is a promising concept to use in anterior cruciate ligament (ACL) injury prevention, as the key for risk reduction is to improve quality of movement. The goal of this study was to better understand why improved motor learning occurred when football players had the opportunity to choose when to receive feedback when practicing sidestep cutting (SSC) movements. Healthy male recreational football players ( n = 22, 22.9 ± 1.7 years, 185.5 ± 7.2 cm, 79.3 ± 9.2 kg) were included and assigned to the self-control (SC) or the yoked (YK) group. The players performed anticipated and unanticipated SSC. They received video instructions and were instructed to "copy the movement of the model to the best of their ability." During the training blocks, the SC group could ask for feedback, whereas the YK group could not. Cutting movement assessment scores (CMAS) were measured to test quality of movement and the Intrinsic Motivation Inventory was administered to measure constructs of motivation. In the anticipated condition, SC group showed better scores in immediate post and the retention test compared with pretest ( p < 0.001), whereas the YK group showed worse scores in the retention test compared with immediate posttest ( p = 0.001). Perceived competence ( p = 0.017) and self-efficacy ( p = 0.032) were consistent factors that correlated with improved CMAS in the SC group. This has given us innovative insights into underlying mechanisms optimizing the quality of movement, necessary to improve current ACL injury prevention approaches.

Abstract: De Marco, K, Goods, PSR, Baldwin, KM, Hiscock, DJ, and Scott, BR. Resistance training prescription during planned deloading periods: A survey of strength and conditioning coaches across varying sporting codes. J Strength Cond Res 38(12): 2099-2106, 2024-The aim of this study was to investigate the resistance training (RT) prescription practices of strength and conditioning coaches throughout 4 common planned deloading periods (taper, competitive season, tournament, and travel). An anonymous online survey was shared globally to coaches, with data from 204 subjects included in analysis (current level of athlete coached: world class n = 68, elite/international n = 62, highly trained n = 64, trained n = 10). Coaches only provided answers about prescription for deloading periods, which they reported encountering. Where a coach indicated not prescribing RT for specific deloading periods, they detailed any barriers preventing RT prescription. Weekly deload RT prescription was typically reported as follows: 1-2 sessions, 30-60 minutes, 1-3 sets, 1-6 repetitions, and between 60 and 84% 1 repetition maximum. Most coaches reported decreasing volume during all deloading periods (taper: 89.1% [163/183 respondents], competitive season: 70.4% [133/189], tournament: 84.1% [74/88], travel: 74.6% [88/118]), with the most common reduction in RT volume reported as 0-25%. Most coaches also decreased intensity during a taper (52.9% [82/155]), tournament (54.8% [40/73]), and travel (53.6% [52/97]), with a 0-25% reduction the most common. Travel had the highest incidence of coaches not prescribing RT (38.5% [75/195]). The most cited barriers by these subjects were "scheduling/time" (60.0% [45/75]) and "lack of equipment and facilities" (57.3% [43/75]), which were also common in other periods. To address common barriers experienced by coaches, researchers should investigate time-efficient RT strategies requiring minimal equipment for periods of planned deloading to maintain training stimulus.

Abstract: Edwards, AM, Coleman, D, Fuller, J, Kesisoglou, A, and Menting, SGP. Time perception and enjoyment of professional soccer players in different training sessions: Implications for assessment of session-RPE and training load. J Strength Cond Res 38(12): e754-e760, 2024-The purpose of this study was to investigate whether the perception of time and enjoyment levels among professional soccer players varied according to the type of training undertaken and whether this influenced the training load (TL) assessment method of session-rating of perceived exertion (sRPE). Sixteen male professional soccer players participated in this study. A diverse range of 7 training events was sampled, comprising passive sessions (e.g., long and short video analysis sessions; VA1 & VA2), sport-specific game play (small-sided games), physical tactical sessions (tactical formation training), individual skills training, and cardiovascular training sessions (long and short; CV1 & CV2). Sessions varied in duration. Subjects estimated duration, enjoyment, and perceived exertion. The activities rated as most enjoyable (all physical training sessions with the exception of CV1 & CV2) were also the sessions considered to last shortest, or time perceived as running fastest (P < 0.01). Long-duration video analysis (VA2) and high-intensity cardiovascular training (without a ball) (CV2) were rated least enjoyable (P < 0.01) and were the sessions where time estimates were longer than chronological time, indicating time perceived as running slow (P < 0.01). Differences in subjective and chronological estimates of sRPE substantially impacted TL estimates across the 5 physically active sessions (P < 0.01). The outcomes of this study indicate that systematic and task-specific variations in time perception and enjoyment exist among professional soccer players. This could be impactful for training design, optimizing the training experience, and reliably assessing TL.

Abstract: Vasileiou, SS, Asimakidis, ND, Dalamitros, AA, and Manou, V. Effects of an 8-week in-season explosive power training program on neuromuscular performance and lower limb asymmetries in young male soccer players. J Strength Cond Res 38(12): 2121-2128, 2024-This study analyzed the effects of incorporating 8 weeks of twice-weekly explosive power training on neuromuscular performance and lower-limb asymmetries applied to soccer. Thirty-five young male soccer players were randomly assigned to either the experimental group (EXP: n = 18; mean age: 13.7 ± 0.8 years; height: 166.9 ± 8.4 cm; body mass: 58.5 ± 12.8 kg) or the control group (CON: n = 17; mean age: 13.7 ± 0.9 years; height: 168.8 ± 9.1 cm; body mass: 58.0 ± 11.4 kg). Before (TP 1 ) and after the training period (TP 2 ) neuromuscular performance (countermovement jump [CMJ], 10 and 20 m sprint times [T10 and T20], change of direction ability [COD]) and lower-limb asymmetries (single-leg CMJ [SLCMJ]) were evaluated. The asymmetry index (AI) for COD and CMJ tests was also calculated. Significant differences (from TP 1 to TP 2 ) were revealed for all the tested parameters in the EXP group (1.50-4.9%, p < 0.00 to 0.12, effect size [ES] = -0.44 to 0.27). For the CON group, T10, T20 505 for nondominant limb and SLCMJ performances for both limbs were significantly improved (0.85 to 1.5%, p < 0.00 to 0.21, ES = -0.36 to 0.37). Finally, the AI remained relatively unchanged for both tests and groups (1.28-3.33%, p = 0.162-0.521). These results indicate that adding twice-weekly explosive power training for 8 weeks can improve neuromuscular performance and reduce lower-limb asymmetries to a greater degree than soccer training alone in young male soccer players.