Efeito do treinamento de estabilidade de força dos músculos flexores plantares na oscilação postural de idosas

BARBOSA, Roberto Negri. Effect of strength stability training of plantar flexor muscles on the postural oscillation of elderly women 2018. 99 f. Dissertação (Mestrado em Ciências, área de concentração: atividade física e esportes) – Escola de Educação Física e Esporte de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, 2018. Elderly postural control has been studied in order to better understand the factors that lead this population to suffer more falls than young individuals. Greater variability of plantar flexor muscles (PFM) strength appears to be directly associated to lower postural control mainly in young adults. In addition, specific training of PFM strength stability at low intensities seems to decrease force variability of these muscles and also to decrease postural oscillation of young adults. However, there is a lack of clarification about the association between PFM force variability and postural oscillation in elderly population, as well as the effects of specific stability strength training of these muscles for this same population. Thus, the objective of the present study was to analyze the association between PFM force variability and postural oscillation in elderly, and to examine the effects of strength stability training on PFM force variability in the muscle coactivation of anterior tibial muscles (AT) and medial gastrocnemius (MG) and in the body oscillation of these elderly women. For this, 40 elderly women were divided into four groups: Group TG5 (n = 10) who performed training at 5% of maximal voluntary isometric contraction (MVIC) of PFM; TG10 group (n = 10) who performed training at 10% of the MVIC of PFM; TGLP group (n = 10) who underwent training at 10% of a maximum repetition of the PFMs in the Leg Press equipment; Group CG (n = 10) who did not perform any specific training for PFMs and was used as control. Body oscillation was evaluated during maintenance of upright bipodal posture, PFM force variability, and muscle coactivation of AT and MG muscles before and after the training period. This training was performed once a week for four weeks. In each training session participant performed five series in which he maintained for 30 seconds the isometric force of plantar flexion, according to the specifications of his group. The results showed that the PFM force stability training performed by TG5, TG10 and TGLP groups was efficient and decreased the strength variability of the participants in the 5% condition of the MVIC with visual feedback, in addition, showed that the TG5 group also decreased its force variability to the 10% MVIC condition with visual feedback. Regarding the postural control, it was observed that the TG5 and TG10 groups increased their mean amplitude of oscillation in the anteroposterior direction after the training. Regarding the activation of the AT and MG muscles, the TG5 and TG10 groups decreased the muscle activation rate for the 5% and 10% conditions with visual feedback after the training and the TG5 group still showed a decrease of the coactivation for the condition 5% without visual feedback. Finally, the results pointed out that for the elderly population there is no relation between the PFM strength variability and the posture control. Therefore, these results indicate that, in the elderly population, there is no association between postural control and PFM strength variability, and even though the effect of training on posture control is not clear, the reduction in strength variability and muscle coactivation can be interpreted as a gain in terms of motor control.