The aim of the present study was to compare the acute effects of constant torque (CT) and constant angle (CA) stretching exercises on the maximum range of motion (ROMmax), passive stiffness (PS), and ROM corresponding to the first sensation of tightness in the posterior thigh (FSTROM). Twenty-three sedentary men (age, 19-33 years) went through 1 familiarization session and afterward proceeded randomly to both CA and CT treatment stretching conditions, on separate days. An isokinetic dynamometer was used to analyze hamstring muscles during passive knee extension. The subjects performed 4 stretches of 30 seconds each with a 15-second interval between them. In the CA stretching, the subject reached a certain ROM (95% of ROMmax), and the angle was kept constant. However, in the CT stretching exercise, the volunteer reached a certain resistance torque (corresponding to 95% of ROMmax) and it was kept constant. The results showed an increase in ROMmax for both CA and CT (p < 0.001), but the increase was greater for CT than for CA (CA vs. CT in poststretching, p = 0.002). Although the PS decreased for both CA and CT (p < 0.001), the decrease was greater for CT than for CA (CA vs. CT in poststretching, p = 0.002). The FSTROM increased for both CA and CT, but the increase for CT was greater than that for CA (CA vs. CT in poststretching, p = 0.003). The greater increase in ROMmax for the CT stretch may be explained by greater changes in the biomechanical properties of the muscle-tendon unit and stretch tolerance, as indicated by the results of PS and FSTROM.

O alongamento é uma prática comum no treinamento da flexibilidade, porém existe uma deficiência de informações específicas sobre os componentes da carga utilizados, em especial, sobre a intensidade do alongamento. O presente estudo teve como objetivo investigar o efeito agudo de duas diferentes intensidades de alongamento na amplitude de movimento (ADM) de extensão do joelho. Participaram deste estudo 14 voluntários do sexo masculino. Os dois membros inferiores de cada participante foram avaliados, sendo que um membro executou o treinamento na intensidade submáxima de alongamento (TS, N=14) e o outro na intensidade máxima de alongamento (TM, N=14). O treinamento utilizou a técnica passiva-estática executando quatro repetições com duração de 15 segundos. Foi encontrada diferença estatisticamente significativa para os valores de ADM entre o pré-teste (68,0±10,5) e o pós-teste (74,0±10,0) no TM. Os valores de ADM para o pré-teste (68,9±14,0) e o pós-teste (71,0±14,4) no TS não apresentaram diferença significativa. Os resultados analisados através da ANOVA two-way apresentaram interação significativa entre o grupo e o teste (F=1.26; df=8,62; p=0,007). O estudo demonstrou que o treinamento na intensidade máxima de alongamento promove aumento agudo da ADM. Dessa forma, os estudos que avaliam os componentes ideais da carga de treinamento na melhora da flexibilidade não devem negligenciar o controle da intensidade do estímulo de alongamento. Palavras-chave: flexibilidade, treinamento, biomecânica. ABSTRACTStretching is a usual practice in flexibility training; however, specific information on load is still scarce, mainly about what concerns the stretching intensity. The aim of the present study was to investigate the acute effect of two stretching intensities in the range of motion (ROM) of knee extension, after a single training session. Fourteen males participated in this study. Both lower limbs of each volunteer were assessed, being one leg submitted to a submaximal stretching program (SSP) and the other to a maximal stretching program (MSP). The training session consisted of four static-passive hamstring stretching repetition of fifteen seconds each. MSP exhibited a significant difference between pre-test (68.0 ± 10.5) and post-test (74.0 ± 10.0) to the ROM figures. However, significant difference was not found for the pre-test (68.8 ± 14.0) and post-test (70.9 ± 14.4) for the SSP. The results analyzed through two-way ANOVA method showed significant interaction between the group and the test (F= 1.26; df= 8.62; p= 0.007). These findings demonstrated that the maximal stretching program causes an acute increase at ROM. Thus, the studies to assess the ideal training load components in order to improve flexibility should not take the stimulus intensity control for granted.

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