Impacto da prescrição de diferentes intensidades do alongamento, controladas de forma objetiva e subjetiva, nas respostas mecânica e sensorial da unidade músculo tendão

Abstract

Traditionally, the performance of flexibility is measured by the maximum range of motion (ROMMAX). This physical capacity is inserted in several contexts, rehabilitation musculoskeletal injuries and sports practice. Although flexibility is fundamental in several areas, aspects related to the intensity of stimulus to stretching, as well as how to control it subjectively during training and how to determine it from the continuum of tolerance to stretching have not yet been explored. The aim of the present study was to compare the acute effects of prescription of two stretching intensities, controlled objectively and subjectively, on mechanical responses (maximum torque (TorqueMÁX, stiffness, energy) and sensory (ROMMAX, first sensation of stretching (ROMFST e TorqueFST), sensation corresponding to the midpoint between the ROMFST and the ROMMAX (ROM50% e Torque50%) of the muscle - tendon unit (UMT). Participated in this experiment sixteen men, aged between 21-31 years. The volunteers underwent two familiarization sessions, one control session and, randomly across the Latin square, four training conditions (intensity – TorqueFST and Torque50%, in which they were subjectively and / or objectively controlled), separated by interval of 48 to 72 hours. Six sets of 30s of stretch were performed on the hamstring muscles, for each condition, in the isokinetic dynamometer (Flexmachine). The analysis of the results was performed from the absolute mean change between (post) - (pre) test. The two-way ANOVA with repeated measures did not find a significant difference between the ways of controlling intensity (CS versus CO) for any of the study variables, regardless of the intensity of stretching. For the intensity factor (TorqueFST versus Torque50%), it was demonstrated, after training, the significant increase of ROMMAX in both intensities, being this one significantly higher for the intensity Torque50% (9.39 °) (p <0.05) , compared to the TorqueFST intensity (6.32 °). There was a reduction in stiffness and energy for both intensities (p <0.05), with no difference between TorqueFST (-0,074 Nm / º; -19,648 Nm * º) and Torque50% (-0,118 Nm / º; -25,804 Nm * º) (p> 0.05), respectively. The variables TorqueMÁX, ROM50%, Torque50% and ROMFST increased only for the intensity Torque50%, respectively (10,71 Nm, 9,32 °, 4,94 Nm, 6,41 °) (p <0,05). No difference in TorqueFST was found for intensity TorqueFST (-0.57), Torque50% (1.13 Nm) and CON (-0.48 Nm) (F(1,15) = 0,305; p=0,589). Thus, it can be concluded that the CS proposal, of the present study, has been shown to be effective in controlling intensity, since both intensities (TorqueFST and Torque50%), determined from the continuum of tolerance to stretching, were efficient in the increase of ROMMAX. The Torque50% intensity increases in greater magnitude, possibly, because it provided sensory and mechanics changes in UMT.