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Purpose: This study explored the effects of 4 bench-press (BP) training programs with different velocity-loss (VL) thresholds (0%, 15%, 25%, and 50%) on strength gains and neuromuscular adaptations., Methods: Forty-six resistance-trained men (22.8 [4.4] y) were randomly assigned into 4 groups that differed in the VL allowed within the set: 0% (VL0), 15% (VL15), 25% (VL25), and 50% (VL50). Training loads (40%-55% 1-repetition maximum), frequency (2 sessions/wk), number of sets (3), and interset recovery (4 min) were identical for all groups. Participants completed the following tests before and after an 8-week (16-session) BP training program: (1) maximal isometric test, (2) progressive loading test, and (3) fatigue test in the BP exercise. During all tests, triceps brachii muscle electromyography was assessed., Results: After completing the resistance-training program, no significant group × time interactions were noticed for isometric and dynamic BP strength variables. The dose-response relationship exhibited an inverted U-shaped relationship pattern, with VL25 showing the greatest effect sizes for almost all strength variables analyzed. The total number of repetitions performed during the training program increased as the VL magnitude increased., Conclusions: The group that trained with high VL threshold (50%), which performed a total of 876 repetitions, did not experience additional strength gains compared with those experienced by the 0%, 15%, and 25% of VL groups, which performed significantly fewer repetitions (48, 357, and 547, respectively). These findings suggest that when light loads (40%-55% 1-repetition maximum) are used, low and moderate VL thresholds (0%-25%) provide a higher training efficiency.

Introduction: Early increases in muscle strength following unilateral resistance training are typically accompanied by strength gains in the contralateral untrained muscles, a phenomenon known as cross-education. However, the specific motor unit adaptations responsible for this gain transfer remain poorly understood. To address this gap, we recorded myoelectrical activity from the biceps brachii using high-density electromyography. Methods: Nine participants performed 8-week unilateral resistance training and were compared to nine control individuals who did no intervention. Discharge characteristics of longitudinally tracked motor units were assessed during maximal voluntary contractions and isometric ramp contractions at 35% and 70% of the maximal voluntary force (MVF) at baseline (T0), 4 weeks (T1), and 8 weeks (T2) post-intervention. Results: MVF increased by 7% in untrained muscles at T1 and 10% at T2 (p < 0.05). These gains were accompanied by significant decreases in motor unit recruitment thresholds (p < 0.01) and higher net discharge rate (i.e., gain in discharge rate from recruitment to peak) following intervention (p < 0.05). Trained muscles presented greater MVF (+11%, T1; +19%, T2) with similar motor unit adaptations, including a lower recruitment threshold (p < 0.01) and a higher net discharge rate (p < 0.01). Discussion: Our findings indicate that higher strength in untrained muscles is associated with a higher net discharge rate, implying a greater spinal motoneuron output to muscles. The present results underscore the role of motor unit adaptations in the transfer of strength gains to non-trained muscles, offering novel insights into the neural mechanisms underlying cross-education. [ABSTRACT FROM AUTHOR]

Background/Objectives: This study aimed to evaluate the effects of an 8-week combined plyometric and resistance training program on the physical fitness (PF) of adolescent girls aged 12 to 15 years. The objective was to determine whether combined training (CT) would yield greater improvements in performance measures compared to resistance training (RT) alone. Methods: Forty-seven adolescent girls were randomly assigned to either the CT group or the RT group. Performance measures such as the 20 m sprint, squat jump, vertical jump, handgrip strength, and flexibility (sit and reach test) were assessed before and after the 8-week intervention. Changes in these measures were analyzed to compare the effects of the two training approaches. Results: The CT group showed a significant reduction in sprint time (−6.5%) compared to the RT group (−4.1%), although the difference was not statistically significant. Squat jump height improved significantly by 5.6% in the CT group compared to 1.1% in the RT group (p < 0.05). Similarly, vertical jump height increased by 6.7% in the CT group and by 2.4% in the RT group (p < 0.05). Handgrip strength improved by 7.5% in the CT group and 4.6% in the RT group, with no significant differences between the groups. Flexibility showed slight, non-significant improvements in both groups. Conclusions: The findings suggest that a combined plyometric and RT program is more effective in enhancing explosive power, specifically squat and vertical jump performance, in adolescent girls compared to RT alone. These results highlight the potential of CT programs for improving overall physical performance in this population. [ABSTRACT FROM AUTHOR]

IntroductionEarly increases in muscle strength following unilateral resistance training are typically accompanied by strength gains in the contralateral untrained muscles, a phenomenon known as cross-education. However, the specific motor unit adaptations responsible for this gain transfer remain poorly understood. To address this gap, we recorded myoelectrical activity from the biceps brachii using high-density electromyography.MethodsNine participants performed 8-week unilateral resistance training and were compared to nine control individuals who did no intervention. Discharge characteristics of longitudinally tracked motor units were assessed during maximal voluntary contractions and isometric ramp contractions at 35% and 70% of the maximal voluntary force (MVF) at baseline (T0), 4 weeks (T1), and 8 weeks (T2) post-intervention.ResultsMVF increased by 7% in untrained muscles at T1 and 10% at T2 (p < 0.05). These gains were accompanied by significant decreases in motor unit recruitment thresholds (p < 0.01) and higher net discharge rate (i.e., gain in discharge rate from recruitment to peak) following intervention (p < 0.05). Trained muscles presented greater MVF (+11%, T1; +19%, T2) with similar motor unit adaptations, including a lower recruitment threshold (p < 0.01) and a higher net discharge rate (p < 0.01).DiscussionOur findings indicate that higher strength in untrained muscles is associated with a higher net discharge rate, implying a greater spinal motoneuron output to muscles. The present results underscore the role of motor unit adaptations in the transfer of strength gains to non-trained muscles, offering novel insights into the neural mechanisms underlying cross-education.

Introduction: Previous studies ranging from 2 to 12 wk of sprint interval training (SIT) have reported improvements in maximal oxygen uptake (...O2max) and neuromuscular function in sedentary populations. However, whether the time course of the changes in these variables correlates with greater training volumes is unclear. Methods: Thirteen sedentary participants performed three all-out training weekly sessions involving 15-s sprints interspersed with 2 min of recovery on a cycle ergometer. The 6-wk training program was composed of three identical blocks of 2 wk in which training volume was increased from 10 to 14 repetitions over the first four sessions and reduced to 8 in the last session. The power output and the heart rate (HR) were monitored during the sessions. The ...O2max, the power-force-velocity profile, and the isometric force were assessed every 2 wk from baseline. Results: A significant increase in ...O2max was observed from the second week plateauing thereafter despite four additional weeks of training. The dynamic force production increased from the second week, and the speed production decreased by the end of the protocol. The isometric force and the maximal power output from the power-force-velocity profile did not change. Importantly, the time spent at high percentages of the maximal HR during the training sessions was lower in the second and third training block compared with the first. Conclusions: SIT resulted in an effective approach for rapidly increasing ...O2max, and no change in the isometric force was found; cycling-specific neuromuscular adaptations were observed from the second week of training. SIT may be useful in the short term, but further improvement of overall physical fitness might need other training modalities like endurance and/or resistance training. [ABSTRACT FROM AUTHOR]

Purpose: To compare the concentric and eccentric training effects on fatigue induced by eccentric and concentric protocols. Methods: A total of 22 men and women (22 [3.6] y) were assigned to concentric (GCON, n = 11) or eccentric training (GECC, n = 11). The concentric (CON) and eccentric (ECC) protocols were composed of 4 sets of 20 knee-extension/flexion repetitions. Force losses were analyzed by comparing 10 repetitions' mean torques during the protocols and by verifying the maximal voluntary contraction and rate of torque development before and after the protocols. Muscle damage was assessed using echo intensity of the vastus lateralis 48 h after the protocols. Training consisted of 6 wk of isokinetic exercise at 60°/s (concentric or eccentric) twice weekly. Results: Before training, both protocols resulted in dynamic and isometric force losses in GCON and GECC (P <.01), but the magnitude was greater after the CON protocol than after the ECC protocol (P <.001). After training, both GCON and GECC showed similar force decreases during the CON and ECC protocols (P <.01), and these changes were not different from the pretraining decreases. Regarding maximal voluntary contraction after training, GECC showed lower force decreases than GCON after ECC exercise (−13.7% vs −22.3%, respectively, P <.05), whereas GCON showed lower maximal voluntary contraction decreases after CON exercise compared with pretraining (−29.2%, P <.05). Losses in rate of torque development were similar after the protocols before and after the training regimens. No changes in echo intensity were observed after the protocols before and after training. Conclusion: Both interventions resulted in similar force decreases during fatigue protocols compared with those associated with pretraining. [ABSTRACT FROM AUTHOR]

Bergamasco, JGA, Gomes da Silva, D, Bittencourt, DF, Martins de Oliveira, R, Júnior, JCB, Caruso, FC, Godoi, D, Borghi-Silva, A, and Libardi, CA. Low-load resistance training performed to muscle failure or near muscle failure does not promote additional gains on muscle strength, hypertrophy, and functional performance of older adults. J Strength Cond Res 36(5): 1209–1215, 2022—The aim of the present study was to compare the effects of low-load resistance training (RT) protocols performed to failure (FAI), to voluntary interruption (VOL), and with a fixed low repetitions (FIX) on muscle strength, hypertrophy, and functional performance in older adults. Forty-one subjects (60–77 years) were randomized into one of the RT protocols (FAI, VOL, or FIX) and completed 12 weeks of RT at 40% of 1 repetition maximum (1RM), twice a week. The assessments included 1RM test, muscle cross-sectional area (CSA), rate of torque development (RTD), and functional performance (chair stand [CS], habitual gait speed [HGS], maximal gait speed [MGS], and timed up-and-go [TUG]). All protocols significantly increased 1RM values from Pre (FAI: 318.3 ± 116.3 kg; VOL: 342.9 ± 93.7 kg; FIX: 328.0 ± 107.2 kg) to Post (FAI: 393.0 ± 143.1 kg, 23.5%; VOL: 423.0 ± 114.5 kg, 23.3%; FIX: 397.8 ± 94.6 kg, 21.3%; p < 0.0001 for all groups). Regarding CS, all protocols showed significant improvements from Pre (FAI: 11.5 ± 2.4 seconds; VOL: 12.1 ± 2.5 seconds; FIX: 11.3 ± 1.1 seconds) to Post (FAI: 10.5 ± 1.1 seconds, −8.5%, p = 0.001; VOL: 10.3 ± 1.5 seconds, −15.1%, p = 0.001; FIX: 11.0 ± 1.1, −3.2%, p = 0.001). Habitual gait speed values increased significantly from Pre (FAI: 1.3 ± 0.2 m·s−1; VOL: 1.3 ± 0.1 m·s−1; FIX: 1.3 ± 0.1 m·s−1) to Post (FAI: 1.4 ± 0.2 m·s−1, 2.5%, p = 0.03; VOL: 1.4 ± 0.2 m·s−1, 5.2%, p = 0.036; FIX: 1.4 ± 0.1 m·s−1, 5.7%, p = 0.03). No significant differences between protocols were found (p > 0.05). In addition, there were no significant changes in CSA, RTD, MGS, and TUG for any protocols (p > 0.05). In conclusion, low-load RT performed without muscle failure promotes significant improvements in muscle strength and some parameters of functional performance in older adults. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to compare the effects of four resistance training (RT) programs with different velocity loss (VL) thresholds: 0% (VL0), 10% (VL10), 20% (VL20), and 40% (VL40) on sprint and jump performance, muscle strength, neuromuscular, muscle hypertrophy, and architectural adaptations. Methods: Sixty-four young resistance-trained men were randomly assigned into four groups (VL0, VL10, VL20, and VL40) that differed in the VL allowed in each set. Subjects followed an RT program for 8 wk (two sessions per week) using the full-squat (SQ) exercise, with similar relative intensity (70%–85% 1-repetition maximum), number of sets (3), and interset recovery period (4 min). Before and after the RT program, the following tests were performed: 1) muscle hypertrophy and architecture of the vastus lateralis (VLA), 2) tensiomyography, 3) 20-m running sprint, 4) vertical jump, 5) maximal voluntary isometric contraction in SQ, 6) progressive loading test in SQ, and 7) fatigue test. Results: No between-group differences existed for RT-induced gains in sprint, jump, and strength performance despite the differences in the total volume performed by each group. VL20 and VL40 showed significant increases (P < 0.001) in muscle hypertrophy (group–time interaction, P = 0.06). However, only VL40 exhibited a significant slowing (P < 0.001) of the delay time in the VLA muscle (group–time interaction, P = 0.05). Moreover, VL40 showed a significant decrease in the early rate of force development (P = 0.04). Conclusions: Higher VL thresholds (i.e., VL20 and VL40) maximized hypertrophic adaptations, although an excessive VL during the set (i.e., VL40) may also induce negative neuromuscular adaptations. Therefore, moderate VL thresholds should be chosen to maximize strength adaptations and to prevent negative neuromuscular adaptations. [ABSTRACT FROM AUTHOR]

Combined strength and aerobic training programs are widely used for improving markers of physical fitness and health. We compared the efficiency of a serial and an integrated combined training program on health and overall fitness in middle-aged females. 54 females (46.7 ± 4.5yrs) were assigned to a serial (SCG)or an integrated (ICG) combined training group or to a control group (CG). The SCG and ICG performed a 3-month training combining aerobic dance and calisthenics. The 2 training programs differ in the sequence of aerobic and strength exercises. SCG performed the strength exercises prior to aerobic; in ICG, the aerobic and strength exercises were altered in a predetermined order. Body composition/circumferences, blood pressure, respiratory function, flexibility, balance, muscle strength/endurance, power and aerobic capacity were measured before and after training. SCG and ICG significantly increased muscle strength and endurance, power, aerobic capacity, flexibility, balance, fat-free mass and respiratory function (p < 0.001 -0.05), while significant reductions were observed for blood pressure, heart rate and body fat/circumferences (p< 0.001-0.05). However, there were no significant differences between SCG and ICG after training. Serial and integrated combined training programs confer analogous adaptations and can be used interchangeably for counteracting the detrimental effects of sedentary lifestyle on indices of physical fitness and health. [ABSTRACT FROM AUTHOR]

SPORTING MOVEMENTS OFTEN INVOLVE JUMP LANDINGS FROM A VARIETY OF HEIGHTS AND DISTANCES. THESE JUMP LANDINGS ARE ASSOCIATED WITH HIGH GROUND REACTION FORCES. ALTHOUGH ATHLETES MAY HAVE THE CAPABILITY TO ABSORB THESE JUMP-LANDING IMPACTS, INCORRECT LANDING TECHNIQUE, INSUFFICIENT MUSCULAR STRENGTH, AND A LACK OF BALANCE AND NEUROMUSCULAR CONTROL PLACE THE LOWER EXTREMITIES UNDER RISK OF INJURY. DESIGNING AND IMPLEMENTING JUMP-LANDING TRAINING INTEGRATING CORRECT LANDING PRINCIPLES AND SPECIFIC CONDITIONING OF THE LOWER LIMB MAY HELP TO REDUCE INJURY PREVALENCE AND IMPROVE PERFORMANCE. THIS ARTICLE FOCUSES ON TARGETED STRATEGIES AND SYSTEMATIC PROGRESSIONS FOR THE DEVELOPMENT OF JUMP-LANDING PROFICIENCY FOR FEMALE ATHLETES. [ABSTRACT FROM AUTHOR]