title: The effect of hip rotation on shear elastic modulus of the medial and lateral hamstrings during stretching.
abstract: 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.
authors.affiliation: Human Health Sciences, Graduate School of Medicine, Kyoto University, Japan. Electronic address: umegaki.hiroki.86x@st.kyoto-u.ac.jp.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Umegaki
authors.affiliation: Human Health Sciences, Graduate School of Medicine, Kyoto University, Japan.
authors.forename: Tome
authors.initials: T
authors.lastname: Ikezoe
authors.affiliation: Human Health Sciences, Graduate School of Medicine, Kyoto University, Japan; Faculty of Health and Sports Science, Doshisha University, Kyoto, Japan.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Nakamura
authors.affiliation: Human Health Sciences, Graduate School of Medicine, Kyoto University, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Nishishita
authors.affiliation: Human Health Sciences, Graduate School of Medicine, Kyoto University, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: Human Health Sciences, Graduate School of Medicine, Kyoto University, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Fujita
authors.affiliation: Human Health Sciences, Graduate School of Medicine, Kyoto University, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Tanaka
authors.affiliation: Human Health Sciences, Graduate School of Medicine, Kyoto University, Japan.
authors.forename: Noriaki
authors.initials: N
authors.lastname: Ichihashi
mesh_terms: D055119:Elastic Modulus; D054459:Elasticity Imaging Techniques / Q000379:methods*; D064368:Healthy Volunteers; D006621:Hip Joint / Q000000981:diagnostic imaging* / Q000502:physiology*; D006801:Humans; D007866:Leg / Q000000981:diagnostic imaging* / Q000502:physiology*; D008297:Male; D052580:Muscle Stretching Exercises; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging* / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology; D012399:Rotation; D055815:Young Adult
keywords: Hamstrings; Hip rotation; Stretching; Ultrasonic shear wave elastography