Satoru Nishishita

Acute effects of static stretching on muscle hardness of the medial gastrocnemius muscle belly in humans: an ultrasonic shear-wave elastography study.

This study investigated the acute effects of static stretching (SS) on shear elastic modulus as an index of muscle hardness and muscle stiffness and the relationship between change in shear elastic modulus and change in muscle stiffness after SS. The patients were 17 healthy young males. Muscle stiffness was measured during passive ankle dorsiflexion using a dynamometer and ultrasonography before (pre) and immediately after (post) 2 min of SS. In addition, shear elastic modulus was measured by a new ultrasound technique called ultrasonic shear wave elastography. The post-SS values for muscle stiffness and shear elastic modulus were significantly lower than the pre-SS values. In addition, Spearmans rank correlation coefficient indicated a significant correlation between rate of change in shear elastic modulus and rate of change in muscle stiffness. These results suggest that SS is an effective method for decreasing shear elastic modulus as well as muscle stiffness and that shear elastic modulus measurement using the shear wave elastography technique is useful in determining the effects of SS.

Acute effects of static stretching on the hamstrings using shear elastic modulus determined by ultrasound shear wave elastography: Differences in flexibility between hamstring muscle components

BACKGROUND Static stretching (SS) with hip flexion and knee extension is often used to stretch the hamstrings. However, it is unclear whether there are the differences in the acute effect of this SS maneuver on flexibility between each component of the hamstrings, namely the semitendinosus (ST), semimembranosus (SM), and biceps femoris (BF) muscles. OBJECTIVES The aims of this study were to investigate the acute effects of SS on the flexibility of the individual muscle components of the hamstrings, and to examine the difference in the acute effect of SS between these components using shear elastic modulus as the index of muscle flexibility. METHOD Twenty healthy men (age, 23.4 ± 2.3 years) volunteered for this study. The shear elastic modulus of the ST, SM and BF muscles were measured using ultrasound shear wave elastography before (PRE) and immediately after (POST) 5 min of SS. Measurements of shear elastic modulus were taken with the knee at 90° (slack position) and 45° (extension position) of flexion. RESULTS In all muscles, the shear elastic modulus at both knee angles decreased significantly after SS. The percentage change in the shear elastic modulus from PRE to POST in the muscles at 45° of knee flexion was greatest in the SM. CONCLUSIONS These results suggest that SS with hip flexion and knee extension has acute effects on increasing flexibility of the hamstring muscle components, especially the SM muscle.

The effect of hip rotation on shear elastic modulus of the medial and lateral hamstrings during stretching

Regarding hamstring stretching methods, many studies have investigated the effect of stretching duration or frequency on muscle stiffness. However, the most effective stretching positions for hamstrings are unclear because it is impossible to quantify muscle elongation directly and noninvasively in vivo. Recently, a new ultrasound technology, ultrasonic shear wave elastography, has permitted noninvasive and reliable measurement of muscle shear elastic modulus, which has a strong linear relationship to the amount of muscle elongation. This study aimed to investigate the effect of hip internal and external rotation on shear elastic modulus of the lateral and medial hamstrings, respectively, during stretching in vivo using ultrasonic shear wave elastography. Twenty-three healthy men (age, 23.0 ± 2.1 years) were recruited for this study. To investigate the effect of hip rotation on the elongation of the medial and lateral hamstrings, shear elastic modulus of the biceps femoris (BF) and semitendinosus (ST) was measured at rest (a supine position with 90° knee flexion, 90° hip flexion, and hip neutral rotation) and in seven stretching positions (with 45° knee flexion and hip internal, external, and neutral rotation) using ultrasonic shear wave elastography. In both BF and ST, the shear elastic modulus in the rest position was significantly lower than that in all stretching positions. However, no significant differences were seen among stretching positions. Our results suggest that adding hip rotation at a stretching position for the hamstrings may not have a significant effect on muscle elongation of the medial and lateral hamstrings.

Effects of two stretching methods on shoulder range of motion and muscle stiffness in baseball players with posterior shoulder tightness: a randomized controlled trial.

BACKGROUND The cross-body stretch and sleeper stretch are widely used for improving flexibility of the posterior shoulder. These stretching methods were modified by Wilk. However, few quantitative data are available on the new, modified stretching methods. A recent study reported the immediate effects of stretching and soft tissue mobilization on the shoulder range of motion (ROM) and muscle stiffness in subjects with posterior shoulder tightness. However, the long-term effect of stretching for muscle stiffness is unknown. The objective of this study was to examine the effects of 2 stretching methods, the modified cross-body stretch (MCS) and the modified sleeper stretch (MSS), on shoulder ROM and muscle stiffness in baseball players with posterior shoulder tightness. METHODS Twenty-four college baseball players with ROM limitations in shoulder internal rotation were randomly assigned to the MCS or MSS group. We measured shoulder internal rotation and horizontal adduction ROM and assessed posterior shoulder muscle stiffness with ultrasonic shear wave elastography before and after a 4-week intervention. Subjects were asked to perform 3 repetitions of the stretching exercises every day, for 30 seconds, with their dominant shoulder. RESULTS In both groups, shoulder internal rotation and horizontal adduction ROM were significantly increased after the 4-week intervention. Muscle stiffness of the teres minor decreased in the MCS group, and that of the infraspinatus decreased in the MSS group. CONCLUSIONS The MCS and MSS are effective for increasing shoulder internal rotation and horizontal adduction ROM and decreasing muscle stiffness of the infraspinatus or teres minor.

The effects of a 4-week static stretching programme on the individual muscles comprising the hamstrings

ABSTRACT The aims of this study were to investigate the effects of a 4-week intervention of static stretching (SS) on muscle hardness of the semitendinosus (ST), semimembranosus (SM) and biceps femoris (BF) muscles. Shear elastic modulus was measured by using ultrasound shear wave elastography as the index of muscle hardness. Thirty healthy men (age 22.7 ± 2.2 years) volunteered for this study and were randomly assigned to the SS intervention group (n = 15) or the control group (n = 15). Participants in the SS intervention group received a 4-week stretch intervention for the hamstrings of their dominant leg. Shear elastic moduli of the hamstrings were measured at initial evaluation and after 4 weeks in both groups at a determined angle. In all muscles, the shear elastic modulus decreased significantly after SS intervention. The percentage change in the shear elastic modulus from the value at initial evaluation to after 4 weeks intervention was greatest in the SM. These results suggest that SS intervention has chronic effects on reducing hardness of the hamstring muscle components, especially the SM muscle.

Effect of hip and knee position on tensor fasciae latae elongation during stretching: An ultrasonic shear wave elastography study.

BACKGROUND Decreased flexibility of the tensor fasciae latae is one factor that causes iliotibial band syndrome. Stretching has been used to improve flexibility or tightness of the muscle. However, no studies have investigated the effective stretching position for the tensor fasciae latae using an index to quantify muscle elongation in vivo. The aim of this study was to investigate the effects of hip rotation and knee angle on tensor fasciae latae elongation during stretching in vivo using ultrasonic shear wave elastography. METHODS Twenty healthy men participated in this study. The shear elastic modulus of the tensor fasciae latae was calculated using ultrasonic shear wave elastography. Stretching was performed at maximal hip adduction and maximal hip extension in 12 different positions with three hip rotation conditions (neutral, internal, and external rotations) and four knee angles (0°, 45°, 90°, and 135°). FINDINGS Two-way analysis of variance showed a significant main effect for knee angle, but not for hip rotation. The post-hoc test for knee angle indicated that the shear elastic modulus at 90° and 135° were significantly greater than those at 0° and 45°. INTERPRETATION Our results suggest that adding hip rotation to the stretching position with hip adduction and extension may have less effect on tensor fasciae latae elongation, and that stretching at >90° of knee flexion may effectively elongate the tensor fasciae latae.

Shoulder horizontal abduction stretching effectively increases shear elastic modulus of pectoralis minor muscle

BACKGROUND Stretching maneuvers for the pectoralis minor muscle, which involve shoulder horizontal abduction or scapular retraction, are performed in clinical and sports settings because the tightness of this muscle may contribute to scapular dyskinesis. The effectiveness of stretching maneuvers for the pectoralis minor muscle is unclear in vivo. The purpose of this study was to verify the effectiveness of stretching maneuvers for the pectoralis minor muscle in vivo using ultrasonic shear wave elastography. METHODS Eighteen healthy men participated in this study. Elongation of the pectoralis minor muscle was measured for 3 stretching maneuvers (shoulder flexion, shoulder horizontal abduction, and scapular retraction) at 3 shoulder elevation angles (30°, 90°, and 150°). The shear elastic modulus, used as the index of muscle elongation, was computed using ultrasonic shear wave elastography for the 9 aforementioned stretching maneuver-angle combinations. RESULTS The shear elastic modulus was highest in horizontal abduction at 150°, followed by horizontal abduction at 90°, horizontal abduction at 30°, scapular retraction at 30°, scapular retraction at 90°, scapular retraction at 150°, flexion at 150°, flexion at 90°, and flexion at 30°. The shear elastic moduli of horizontal abduction at 90° and horizontal abduction at 150° were significantly higher than those of other stretching maneuvers. There was no significant difference between horizontal abduction at 90° and horizontal abduction at 150°. CONCLUSIONS This study determined that shoulder horizontal abduction at an elevation of 90° and horizontal abduction at an elevation of 150° were the most effective stretching maneuvers for the pectoralis minor muscle in vivo.

Changes in Passive Properties of the Gastrocnemius Muscle–Tendon Unit During a 4-Week Routine Static-Stretching Program

CONTEXT Static stretching (SS) is commonly performed in a warm-up routine to increase joint range of motion (ROM) and to decrease muscle stiffness. However, the time course of changes in ankle-dorsiflexion (DF) ROM and muscle stiffness during a routine SS program is unclear. OBJECTIVE To investigate changes in ankle-DF ROM, passive torque at DF ROM, and muscle stiffness during a routine SS program performed 3 times weekly for 4 wk. DESIGN A quasi-randomized controlled-trial design. PARTICIPANTS The subjects comprised 24 male volunteers (age 23.8 ± 2.3 y, height 172.0 ± 4.3 cm, body mass 63.1 ± 4.5 kg) randomly assigned to either a group performing a 4-wk stretching program (SS group) or a control group. MAIN OUTCOME MEASURES DF ROM, passive torque, and muscle stiffness were measured during passive ankle dorsiflexion in both groups using a dynamometer and ultrasonography once weekly during the 4-wk intervention period. RESULTS In the SS group, DF ROM and passive torque at DF ROM significantly increased after 2, 3, and 4 wk compared with the initial measurements. Muscle stiffness also decreased significantly after 3 and 4 wk in the SS group. However, there were no significant changes in the control group. CONCLUSIONS Based on these results, the SS program effectively increased DF ROM and decreased muscle stiffness. Furthermore, an SS program of more than 2 wk duration effectively increased DF ROM and changed the stretch tolerance, and an SS program more than 3 wk in duration effectively decreased muscle stiffness.

Acute effect and time course of extension and internal rotation stretching of the shoulder on infraspinatus muscle hardness

BACKGROUND A decrease in flexibility of the infraspinatus muscle causes limitations in the range of shoulder motion. Static stretching (SS) is a useful method to improve muscle flexibility and joint mobility. Previous researchers investigated effective stretching methods for the infraspinatus. However, few researchers investigated the acute effect of SS on the infraspinatus muscles flexibility. In addition, the minimum SS time required to increase the infraspinatus muscles flexibility remains unclear. The aims of this study included investigating the acute effect of SS on the infraspinatus muscles hardness (an index of muscle flexibility) by measuring shear elastic modulus and determining minimum SS time to decrease the infraspinatus muscles hardness. METHODS This included measuring the effect of SS with extension and internal rotation of the shoulder on the infraspinatus muscles hardness in 20 healthy men. Hence, shear elastic modulus of the infraspinatus was measured by ultrasonic shear wave elastography before and after every 10 seconds up to 120 seconds of SS. RESULTS Two-way analysis of variance indicated a significant main effect of SS duration on shear elastic modulus. The post hoc test indicated no significant difference between shear elastic modulus after 10 seconds of SS and that before SS. However, shear elastic modulus immediately after a period ranging from 20 seconds to 120 seconds of SS was significantly lower than that before SS. CONCLUSION The results suggested that shoulder extension and internal rotation SS effectively decreased the infraspinatus muscles hardness. In addition, the results indicated that a period exceeding 20 seconds of SS decreased the infraspinatus muscles hardness.

Influences of fascicle length during isometric training on improvement of muscle strength.

Abstract Tanaka, H, Ikezoe, T, Umehara, J, Nakamura, M, Umegaki, H, Kobayashi, T, Nishishita, S, Fujita, K, Araki, K, and Ichihashi, N. Influences of fascicle length during isometric training on improvement of muscle strength. J Strength Cond Res 30(11): 3249–3255, 2016—This study investigated whether low-intensity isometric training would elicit a greater improvement in maximum voluntary contraction (MVC) at the same fascicle length, rather than the joint angle, adopted during training. Sixteen healthy women (21.8 ± 1.5 years) were randomly divided into an intervention group and a control group. Before (Pre) and after (Post) training, isometric plantarflexion MVCs were measured every 10° through the range of ankle joint position from 20° dorsiflexion to 30° plantarflexion (i.e., 6 ankle angles). Medial gastrocnemius fascicle length was also measured at each position, using B-mode ultrasound under 3 conditions of muscle activation: at rest, 30%MVC at respective angles, and MVC. Plantarflexion resistance training at an angle of 20° plantarflexion was performed 3 days a week for 4 weeks at 30%MVC using 3 sets of twenty 3-second isometric contractions. Maximum voluntary contraction in the intervention group increased at 0 and 10° plantarflexion (0°; Pre: 81.2 ± 26.5 N·m, Post: 105.0 ± 21.6 N·m, 10°; Pre: 63.0 ± 23.6 N·m, Post: 81.3 ± 20.3 N·m), which was not the angle used in training (20°). However, the fascicle length adopted in training at 20° plantarflexion and 30%MVC was similar to the value at 0 or 10° plantarflexion at MVC. Low-intensity isometric training at a shortened muscle length may be effective for improving MVC at a lengthened muscle length because of specificity of the fascicle length than the joint angle.