Efeitos da amplitude de movimento nos exercícios resistidos: respostas na hipertrofia e força muscular

Abstract

The manipulation of range of motion (ROM) directly influences the muscular adaptations resulting from resistance training (RT). Despite this, the absence of specific practical guidelines to optimize the development of maximal strength and muscle hypertrophy, combined with inconsistencies in the literature, highlights the need for a deeper understanding of this topic. Therefore, this thesis aimed to analyze, through a systematic review and a controlled experiment, the effects of RT performed with different ranges of motion on muscle hypertrophy and maximal strength, considering participant characteristics and the training protocols employed. For Study 1, the systematic review, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed, with eligibility criteria defined according to the PICOS framework: (P) healthy men and women over 18 years old, (I) dynamic strength exercises performed with partial range of motion (pROM), (C) dynamic strength exercises with full range of motion (fROM), (O) maximal strength and muscle hypertrophy development, and (S) randomized or non-randomized clinical trials with a minimum duration of six weeks. Searches were conducted on June 16, 2024, in the EMBASE, MEDLINE (via PubMed®), and Web of Science – Core Collection databases, and the methodological quality of the studies was assessed using the Physiotherapy Evidence Database (PEDro) scale. Nineteen studies were included, totaling 627 participants (42.26% untrained, 30.62% trained, 4.14% physically active, 9.4% with little RT experience, and 13.55% with a mixed sample). The exercises covered included upper and lower limbs, as well as single-joint and multi-joint movements. The average methodological quality score was 5.9 (±1.2), indicating moderate quality, with only one study classified as low quality. The main findings of the review showed that for elbow flexor hypertrophy during the Scott curl, there was no clear advantage of fROM over pROM, whereas for muscle strength, fROM tended to produce better results. In the leg extension exercise, both ROM types led to similar hypertrophy and strength gains, except when pROM was performed at longer muscle lengths, which enhanced outcomes. Therefore, muscle length during pROM may be a determining factor for superior gains. However, when analyzing the results of the studies that investigated the squat exercise, it was observed that the fROM group achieved greater hypertrophy of the anterior thigh muscles, thigh adductors, and gluteus maximus. Similarly, regarding muscle strength gains, the fROM group showed significantly greater improvements than the pROM group. For the bench press exercise, there is insufficient evidence to support conclusions regarding strength gains with fROM due to the limited number of studies and heterogeneous samples. Importantly, to date, no studies have analyzed the effect of ROM on hypertrophy for this exercise. Therefore, it can be concluded that ROM does not have a major influence on hypertrophy and strength outcomes when training with the Scott curl and leg extension exercises. However, for the squat, training with fROM may result in greater hypertrophic and strength stimuli. For the bench press, the results remain inconclusive. Additionally, Study 2, a controlled experiment with ten physically active young men (age = 22.90 ± 2.47 years; body mass = 83.85 ± 11.67 kg; height = 176.30 ± 6.22 cm) directly compared final partial range of motion (final pROM) with full range of motion (fROM). The randomized within-subject experimental design involved resistance training for both upper and lower limbs, three times per week for six weeks, with three sets of 12 repetitions at 60% of one-repetition maximum (1-RM) and a two-minute rest interval between sets and limbs. The results showed no statistically significant differences for elbow flexor hypertrophy (p = 0.920; Cohen’s d = 0.046) and knee extensor hypertrophy (p = 0.291; Cohen’s d = 0.152), nor for arm 1-RM (p = 0.161; Cohen’s d = 0.898) and thigh 1-RM (p = 0.276; Cohen’s d = 0.533). However, the moderate-to-large effect sizes favoring final pROM for strength suggest a trend worth exploring in future studies with physically active young men. In summary, the combined results from the systematic review and the experiment indicate that different ranges of motion may lead to similar adaptations in muscle hypertrophy and strength, although longer muscle lengths and the use of final pROM show potential for superior results in certain contexts. The findings supported the evidence from the systematic review, confirming that ROM manipulation has variable impacts depending on the exercise and the muscle group involved. Together, these findings contribute to refining evidence-based guidelines for resistance training prescription focused on strength and muscle hypertrophy. Further research is recommended to confirm these findings and to establish more specific practical guidelines for prescribing ranges of motion in resistance training.