Acute and prolonged effect of static stretching on the passive stiffness of the human gastrocnemius muscle tendon unit in vivo

Abstract

Static stretching (SS) is commonly used to prevent or improve limited joint mobility. However, it is unclear whether the components of the muscle-tendon unit (MTU) are affected by 5 min of SS. This study investigated the acute and prolonged effect of SS on the mechanical properties of the MTU. The subjects comprised 15 male participants (mean age: 21.5 AE 1.6 years). MTU stiffness, muscle stiffness, tendon stiffness, and fascicle length of the gastrocnemius muscle were measured by ultrasonography and a dynamometer while the ankle was passively dorsiflexed. The measurements were performed prior to the 5 min of SS, immediately after the SS, and 10 min after the SS. MTU stiffness and muscle stiffness significantly decreased at both immediately and 10 min after SS, whereas no significant differences in MTU stiffness and muscle stiffness were found between immediately and 10 min after SS. Tendon stiffness immediately after SS was significantly higher than prior to and 10 min after SS. No significant change in the fascicle length occurred after SS. These results suggest that 5 min of SS affects MTU and muscle stiffness both immediately and 10 min after SS, which may be associated with a change in the connective tissue properties. ß

Efeitos agudos do alongamento estático passivo sobre a arquitetura muscular do vasto lateral de jovens saudáveis

“…In the present study, there was an increase in FL with concomitant reduction in FA immediately after static stretching only in the extended knee position, which reinforces some findings in literature 1,12 . However, no change was observed for the flexed knee position.…”

“…Some studies have reported the acute effect of static stretching on muscle architecture 1,[11][12][13] , but the results were inconsistent with each other. While some authors observed an increase in FL and a reduction of FA 1,12 in the gastrocnemius muscle after 5 1-min repetitions of static stretching, others only found FL changes for the vastus lateralis muscle, but not for the femoral biceps muscle 13 after three 30-s repetitions, and did not find any type of alteration for the gastrocnemius muscle after six 45-s repetitions 11 . Differences in the amount of stretching exercises in the protocols to acquire US images, in the joint position in which the measurements were made and in the muscle groups tested, may explain such discrepancies in results.…”

“…This hypothesis has already been demonstrated in literature 18,19 . Although studies have already investigated the acute effect of static stretching on muscle architecture, a large part of them verified this during stretching and used unusual volumes (e.g., 5 min) in a specific group (gastrocnemius) and in only one joint position 1,12 . Another study that measured the muscle architecture parameters after static stretching 13 had influence of strength training performed after stretching, which makes it impossible to know its isolated effect.…”

“…Most studies indicate alterations generated in muscle architecture during stretching exercises and not the acute effect generated after this routine 10 . Moreover, the few studies that verified the acute effect of static stretching on muscle architecture showed controversial results, possibly due to the different methods adopted and muscles tested [11][12][13] . In the study conducted by Morse et al 1 , no significant changes were observed in FL and FA immediately after an extensive routine of five 1-min repetitions of static stretching in the triceps sural muscle.…”

Neuromuscular Diseases and Rehabilitation

“…It has been reported that ROM increases with stretching frequency and the improvement was maintained for 4 weeks after the exercise ends [173]. Surveys show that a little 5-min static stretching causes a change in the muscle-tendon unit [174]. Resting splints can be used during sleep to prevent contractures.…”