Effects of different hip rotations on gluteus medius and tensor fasciae latae muscle activity during isometric side-lying hip abduction.
BACKGROUND
Gluteus medius (Gmed) weakness is associated with some lower-extremity injuries. People with Gmed weakness might compensate by activating the tensor fasciae latae (TFL). Different hip rotations in the transverse plane may affect Gmed and TFL muscle activity during isometric side-lying hip abduction (SHA).


OBJECTIVE
To compare Gmed and TFL muscle activity and the Gmed:TFL muscle-activity ratio during SHA exercise with 3 different hip rotations.


METHODS
The effects of different hip rotations on Gmed, TFL, and the Gmed:TFL muscle-activity ratio during isometric SHA were analyzed with 1-way, repeated-measures analysis of variance.


METHODS
University research laboratory.


METHODS
20 healthy university students were recruited in this study.


METHODS
Participants performed isometric SHA: frontal SHA with neutral hip (frontal SHAN), frontal SHA with hip medial rotation (frontal SHA-MR), and frontal SHA with hip lateral rotation (frontal SHA-LR).


METHODS
Surface electromyography measured the activity of the Gmed and the TFL. A 1-way repeated-measures analysis of variance assessed the statistical significance of Gmed and TFL muscle activity. When there was a significant difference, a Bonferroni adjustment was performed.


RESULTS
Frontal SHA-MR showed significantly greater Gmed muscle activation than frontal SHA-N (P = .000) or frontal SHA-LR (P = .015). Frontal SHA-LR showed significantly greater TFL muscle activation than frontal SHA-N (P = .002). Frontal SHA-MR also resulted in a significantly greater Gmed:TFL muscle-activity ratio than frontal SHA-N (P = .004) or frontal SHA-LR (P = .000), and frontal SHA-N was significantly greater than frontal SHA-LR (P = .000).


CONCLUSIONS
Frontal SHA-MR results in greater Gmed muscle activation and a higher Gmed:TFL muscle ratio.
Dept of Physical Therapy, Yonsei University, Wonju, South Korea.
Ji-hyun
JH
Lee
Heon-seock
HS
Cynn
Sil-ah
SA
Choi
Tae-lim
TL
Yoon
Hyo-jung
HJ
Jeong
D000328:Adult; D002081:Buttocks; D004576:Electromyography; D006615:Hip / Q000502:physiology*; D006801:Humans; D007537:Isometric Contraction; D009068:Movement / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D012399:Rotation; D055815:Young Adult