Análise da força muscular e desempenho funcional em idosos após a aplicação de protocolos utilizando resistência elástica e peso livre: estudo clínico randomizado

Abstract

Resistance Training (RT) is considered the main physical exercise protocol to increase muscle mass and strength in elderly people. Consists of performing exercises with voluntary contractions of skeletal muscle, searching to overcome a resistance, which can be offered by equipment, free weights, elastic implements or by own body weight. The aim of this study was to compare the effects of RT with elastic resistance and free weight on the muscle strength of knee extensors and flexors, and on the functional performance of lower limbs in elderly people. This is a randomized clinical study, with 29 elderly participants of both sexes, randomly allocated into two groups: Training group free weight (GTL, n = 13) and Training group with elastic tube (GTE, n = 16). First, for the analysis of functional performance of the lower limb, the sit and stand test was performed, followed by the two-minute stationary gait test and, at the final, the timed up and go test. To measure peak muscle strength, a portable digital isometric dynamometer was used. The training protocol was performed three times a week, on alternate days, for a total duration of eight weeks. The determination of the training load was obtained by the protocol of 10 maximum repetitions (10 RM) on two occasions: before the beginning of the RT, (using 20% of the training load) in the first 4 weeks - adaptation period - and, after this period, a new 10 RM test was applied to adjust the training load (75% to 85% of 10 RM) in the last 4 weeks. At the end, the aforementioned tests were repeated to compare the results. The results showed a significant difference between the groups when comparing age (p = 0.006). In the assessments of functional performance and peak muscle strength, no significant differences were found, both in intra-group and inter-group comparisons. However, when comparing intragroups (pre and post resistance training), it was observed that both groups significantly increased the training load (10RM) for the extensors (GTL p = 0.0002; GTE p = 0.0001) and knee flexors (GTL p = 0.006; GTE p = 0.0001). In the analysis of the subjective perception of effort, only the GTL group showed a significant increase in knee flexion movement (p = 0.02). Thus, we concluded that, although there are no significant differences in the results of muscle strength and physical performance, both training were effective in increasing the training load observed by the 10RM test of lower limbs in elderly, in knee extension and flexion movements. Thereby, the resistance training with elastic tubes and the free weight training were able to promote similar effects. Regarding to the evaluation using the Borg Scale to measure the intensity of the stimulus, only in the flexion movement in the GTL group showed a significant increase in the subjective perception of effort, considering that there was a greater difficulty in the execution of the knee flexion movement against the elastic resistance.