Influence of Constant Torque Stretching at Different Stretching Intensities on Flexibility and Mechanical Properties of Plantar Flexors

Abstract

Oba, K, Samukawa, M, Nakamura, K, Mikami, K, Suzumori, Y, Ishida, Y, Keeler, N, Saitoh, H, Yamanaka, M, and Tohyama, H. Influence of constant torque stretching at different stretching intensities on flexibility and mechanical properties of plantar flexors. J Strength Cond Res XX(X): 000-000, 2018-The purpose of this study was to examine the effects of constant torque stretching (CTS) at different stretching intensities on the maximal range of motion (ROM) and muscle-tendon unit (MTU) stiffness of plantar flexors. Fourteen healthy men performed 4 trials of differing stretch intensities: no stretching (control), 50, 75, and 100%. Stretch intensity was defined as maximum passive resistive torque predetermined at a familiarization trial. Each stretch trial consisted of 5 sets of 60-second CTS at the designated stretch intensity. Both maximal ROM and passive resistive torque were assessed during passive dorsiflexion, and MTU stiffness was calculated using the torque-angle curves measured before and after CTS. There were no significant differences in maximal ROM or MTU stiffness at the baseline condition. After the intervention, significantly greater maximal ROM and significantly lower MTU stiffness were observed in the 100% CTS condition than the control condition, whereas there were no significant differences between the submaximal intensity condition (i.e., 50 or 75% intensity) and the control condition. Therefore, our findings suggest that maximal intensity stretching is the most effective approach for improving both flexibility and MTU stiffness with CTS.

Acute effects of combined static stretching and electrical stimulation on joint range of motion and passive stiffness

“…SS also decreased MTU stiffness, which is in accordance with previous studies 25‐27 . The relative stretching intensity is one of the important factors that affects the amount of change after SS 3,5,14,31 . Freitas et al 3 showed that SS at the maximum intensity without pain increases the knee joint ROM, whereas SS at intensities of 50% and 75% causes no significant changes in ROM.…”

“…Freitas et al 3 showed that SS at the maximum intensity without pain increases the knee joint ROM, whereas SS at intensities of 50% and 75% causes no significant changes in ROM. Another study also reported that SS at maximum intensity induces greater changes in ankle ROM and MTU stiffness than SS at intensities of 75% and 50% 31 . An animal study reported that SS + ES preserves the number of sarcomeres in series tenotomy, whereas SS does not prevent sarcomere shortening 11 .…”

“…[25][26][27] The relative stretching intensity is one of the important factors that affects the amount of change after SS. 3,5,14,31 Freitas et al 3 showed that SS at the maximum intensity without pain increases the knee joint ROM, whereas SS at intensities of 50% and 75% causes no significant changes in ROM. Another study also reported that SS at maximum intensity induces greater changes in ankle ROM and MTU stiffness than SS at intensities of 75% and 50%.…”

“…Another study also reported that SS at maximum intensity induces greater changes in ankle ROM and MTU stiffness than SS at intensities of 75% and 50%. 31 An animal study reported that SS + ES preserves the number of sarcomeres in series tenotomy, whereas SS does not prevent sarcomere shortening. 11 This suggests that SS + ES may induce greater tension on the muscle than SS alone.…”

Effects of Intermittent and Continuous Static Stretching on Range of Motion and Musculotendinous Viscoelastic Properties Based on a Duration-Matched Protocol

“…Static stretching (SS) increases range of motion (ROM) and reduces musculotendinous stiffness (MTS) [1]. SS has been used in various situations, such as sports, rehabilitation, and health promotion.…”