Effective stretching position for the supraspinatus muscle evaluated by shear wave elastography in vivo

Abstract

[Background]Stretching is useful for increasing flexibility in clinical and athletic situations. Although several authors have recommended various stretching techniques for the supraspinatus muscle, there is no consensus on the effective stretching position owing to a lack of quantitative analysis in vivo. This study used ultrasonic shear wave elastography in vivo to verify the effective stretching positions for the supraspinatus muscle. [Methods]The study participants were 15 healthy male volunteers. The shear elastic modulus, used as the index of supraspinatus muscle elongation, was computed using ultrasonic shear wave elastography. The shear elastic modulus was measured at neutral position and maximum internal rotation in 9 positions: 0° elevation, 90° abduction, 90° flexion, maximum extension, maximum horizontal adduction at 45° and 90° elevation, and maximum horizontal abduction at 20°, 45°, and 90° elevation. [Results]The shear elastic moduli were significantly greater in maximum internal rotation at maximum horizontal abduction with 45° and 90° elevation and maximum internal rotation at maximum extension than those in the other positions. There were no significant differences in the shear elastic moduli among these 3 positions. [Conclusions]This study demonstrated that maximum internal rotation at maximum extension, maximum internal rotation at maximum horizontal abduction with 90° elevation, and maximum internal rotation at maximum horizontal abduction with 45° elevation are effective stretching positions for the supraspinatus muscle.