Efeito de 10 semanas de treinamento e destreinamento da flexibilidade com as técnicas ângulo constante e torque constante nas variáveis biomecânicas e sensoriais nos músculos posteriores da coxa de adultos jovens

Abstract

Stretching exercises are commonly used in rehabilitation of patients with musculoskeletal injuries and in physical training of athletes from different sports. Information on different sensory and biomechanical variables associated with muscle tendon unit (UMT) response to stretch after training and detraining are not yet available for constant angle (AC) and constant torque (TC) techniques. The present study compared the effects of 10 weeks of training and detraining with the AC and TC stretching techniques on range of motion (ADMmáx), maximum torque (Torquemáx), first sensation of stretching (PSDAADM and PSDAtorque), energy, stiffness and angle of peak torque. Participated in this study 30 male university students, aged between 17 and 36 years. The study was approved by the Ethics Committee of the Federal University of Minas Gerais. The volunteers were randomly divided into training group and control group. The volunteers of the training group performed the AC stretching technique in a lower limb while the contralateral limb performed the TC technique, for 10 weeks. The control group did not perform any training during the study period. The measurement of ADMmáx, Torquemáx, PSDAADM and PSDAtorque, energy and stiffness variables were measured before and after training and after detraining period (10 weeks) in the flexmachine device. The angle of peak torque was measured on an isokinetic dynamometer at a speed of 60 °/s before and after training. A Magnetic Resonance imaging (MRI) was performed to measure the cross-sectional area at the end of training period. AC and TC groups performed 40 training sessions with afrequency of four times a week while the control group was instructed not to perform any type of flexibility or strength training during the study. The hamstrings stretching sessions consisted of six repetitions of 30 seconds each, and an approximately 10 seconds rest between repetitions. The one-way ANOVA with repeated measures found no significant differences for any variable for the control group. The two-way ANOVA with repeated measures found no difference between the techniques of AC and TC stretch for any variable investigated, while the time factor (pretest, posttest and detraining) showed a significant increase in ADMmáx, Torquemáx and PSDAADM and PSDATorque variables, and a significant reduction in stiffness in posttest for bothstretching techniques when compared to pretest. The angle of peak torque was not different for time or group factor. After detraining, there was no significant difference between stretching techniques, and the mean value of ADMmáx, Torquemáx and PSDAADM and PSDATorque did not differ from posttest and remained statistically higher than pretest values. Thus, we conclude that the AC and TC stretching techniques were equally effective to change the behavior of ADMmáx, Torquemáx and PSDAADM, PSDATorque and stiffness, and the improvements from training remained for 10 weeks.