The study aimed to compare the effect of performing the same or different exercises for a muscle group on resistance training (RT) sessions on muscle hypertrophy at different sites along muscle length. Twenty-two detrained men (23.3±4.1 years) were randomly allocated to the following groups: a group that performed the same exercises in all training sessions (N-VAR=11) or one that varied the exercises for the same muscle groups (VAR=11). All were submitted to 3 weekly sessions for nine weeks. Muscle thickness was assessed at the proximal, middle, and distal sites of the lateral and anterior thigh, elbow flexors, and extensors by B-mode ultrasound. The VAR group significantly increased all the sites analyzed (P<0.05). Furthermore, the proximal site of the lateral thigh showed a larger relative increase when compared to the middle site (P<0.05). In contrast, the N-VAR group were not revealed significant improvements only for the middle site of the lateral thigh and the proximal site of the elbow flexors (P>0.05). Our results suggest that to perform different resistance exercises can induce hypertrophy of all sites assessed in detrained young men.

Nunes, JP, Costa, BDV, Kassiano, W, Kunevaliki, G, Castro-e-Souza, P, Rodacki, ALF, Fortes, LS, and Cyrino, ES. Different foot positioning during calf training to induce portion-specific gastrocnemius muscle hypertrophy. J Strength Cond Res 34(8): 2347–2351, 2020—The aim of this study was to compare the changes in gastrocnemius muscle thickness (MT) between conditions such as which foot was pointed outward (FPO), foot was pointed inward (FPI), or foot was pointed forward (FPF). Twenty-two young men (23 ± 4 years) were selected and performed a whole-body resistance training program 3 times per week for 9 weeks, with differences in the exercise specific for calves. The calf-raise exercise was performed unilaterally, in a pin-loaded seated horizontal leg-press machine, in 3 sets of 20–25 repetitions for training weeks 1–3 and 4 sets for weeks 4–9. Each subject's leg was randomly assigned for 1 of the 3 groups according to the foot position: FPO, FPI, and FPF. Measurements with a B-mode ultrasound were performed to assess changes in MT of medial and lateral gastrocnemius heads. After the training period, there were observed increases in MT of both medial (FPO = 8.4%, FPI = 3.8%, and FPF = 5.8%) and lateral (FPO = 5.5%, FPI = 9.1%, and FPF = 6.4%) gastrocnemius heads, and significant differences for magnitude of the gains were observed between FPO and FPI conditions (p < 0.05). Positioning FPO potentiated the increases in MT of the medial gastrocnemius head, whereas FPI provided greater gains for the lateral gastrocnemius head. Our results suggest that head-specific muscle hypertrophy may be obtained selectively for gastrocnemius after 9 weeks of calf training in young male adults.

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The assessment of parasympathetic nervous activity and psychophysiological responses infers the stress imposed by different resistance training systems. Therefore, we compare the effects of different sets configurations, with similar volume (~60 repetitions), on heart rate variability indices and internal training load. Twenty-nine resistance-trained adults completed the following conditions: traditional without and with muscle failure, inter-repetition rest, and rest-pause in the parallel squat. The heart rate variability indices (time-domain) were measured before and 30 min after each condition. The internal training load was obtained through the session-rating of perceived exertion method. Except for inter-repetition rest, all conditions reduced the heart rate variability indices after the session (P<0.05), and the rest-pause triggered the higher reductions (≤−46.7%). The internal training load was higher in the rest-pause (≤68.9%). Our results suggest that rest-pause configuration leads to more considerable disruption of the parasympathetic nervous activity and higher internal training load in trained adults. In contrast, inter-repetition rest allows lower autonomic and psychophysiological stress.

BACKGROUND: Traditional and rest-pause systems are commonly used during resistance training. These systems have different rest times between repetitions that might affect neuromuscular status and fatigue level. OBJECTIVE: This study compared the acute effects of traditional and rest-pause resistance exercise done to muscular failure on countermovement jump (CMJ) performance. METHODS: Twenty-nine recreationally strength-trained adults of both sexes aged from 18 to 33 years old performed four experimental resistance exercise sessions (half back-squat exercise) in a randomized order. The experimental conditions were: Traditional system to muscular failure (TR-F; 4 × 15 [15RM]) or non-failure (TR-NF; 5 × 12 [15RM]), and rest-pause system to muscular failure (RP-F; 60 reps with 30 s rest between each failure) or non-failure (RP-NF; 60 reps with 10.2 s rest between each repetition). CMJ height was measured at pre-experiment, Post-15 s, and Post-30 min. Perceived recovery was assessed at pre-experiment, lactate concentration Post-2 min, and rating of perceived exertion Post-30 min. RESULTS: CMJ height decrease occurred at Post-15 s and 30 min for the TR-F, TR-NF, and RP-F sessions (p< 0.05). Interaction effects (p< 0.05) showed exercise to muscle failure (TR-F and RP-F) induced greater neuromuscular decrement at Post-15 s, with RP-F leading to a higher CMJ performance impairment at Post-30 min (p< 0.001). Higher blood lactate concentrations were found following TR-F, TR-NF, and RP-F (p< 0.05) than RP-NF conditions, whereas greater internal training load perception was reported after training to muscular failure (p< 0.05) than non-failure exercise. CONCLUSION: Resistance exercise to muscular failure induced greater CMJ height decrement and internal training load perception than non-failure exercise, with RP-F leading to a higher acute neuromuscular performance impairment.

Costa, BDV, Kassiano, W, Nunes, JP, Kunevaliki, G, Castro-E-Souza, P, Sugihara-Junior, P, Fernandes, RR, Cyrino, ES, and de Fortes, LS. Does varying resistance exercises for the same muscle group promote greater strength gains? J Strength Cond Res 36(11): 3032–3039, 2022—Two of the foremost principles of progression are progressive overload and variation. A way to vary within a resistance training (RT) program is to perform different exercises for the same muscle group; however, this strategy is still overlooked. The purpose of the present study was to compare strength adaptations between an RT routine that maintained the exercises fixed (N-VAR) and another that varied the exercises for the same muscle group during the weekly sessions (VAR). Twenty-three young men (23.3 ± 4.1 years) were randomly allocated to N-VAR (n = 11) and VAR (n = 12) conditions. The RT was performed 3 times a week for 9 weeks and consisted of a whole-body routine (3 sets of 8–12 repetitions). Maximum dynamic strength was assessed using the 1-repetition maximum test (1RM), and the isometric strength was assessed using an isokinetic dynamometer, before and after training. Following the training period, both groups increased the 1RM values in all exercises (p ≤ 0.002), without significant differences between them (p ≥ 0.20). In contrast, a greater increase (p = 0.02) in isometric knee extension strength was showed to N-VAR (+12%) compared with VAR (+7%). There was no significant increase in both groups for isometric knee flexion strength (N-VAR, p = 0.10; VAR, p = 0.18). Our findings indicate that maintaining or varying the exercises for the same muscle group promotes similar adaptations in the maximum dynamic strength. In contrast, for the isometric strength in knee extension, maintaining the fixed exercises seems to be more interesting.

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