Effect of hip angle on neuromuscular activation of the adductor longus and adductor magnus muscles during isometric hip flexion and extension
Neuromuscular activation of the adductor longus (AL) and adductor magnus (AM) muscles at different hip flexion angles during hip flexion and extension has not been clarified. This study aimed to compare the relationship between hip flexion angle and the electromyogram of the AL muscle with that of the AM muscle during isometric hip flexion and extension.
Fifteen healthy young men were included in this study. Participants performed maximal voluntary contractions during hip flexion and extension at six different hip flexion angles: − 20°, 0°, 20°, 40°, 60°, and 80°. The surface electromyograms of the AL and AM muscles were recorded. The root mean square (RMS) was calculated and normalized by the RMS during hip adduction for each individual muscle.
The normalized RMS of the AL muscle was significantly higher than that of the AM muscle at a hip flexion angle of − 20° during hip flexion (P < 0.05). The mean normalized RMS of the AM muscle was significantly higher than that of the AL muscle during hip extension (P < 0.01).
These results suggest that the AL muscle is recruited specifically at the hip-extended position during hip flexion, and that the AM muscle is recruited regardless of the hip position during hip extension. Thus, the AL and AM muscles may have different functional roles in different hip flexion angles.
KeywordsHip adductor muscle group Isometric contraction Hip angle Neuromuscular activation
Analysis of variance
Maximal voluntary contraction
Root mean square
We thank all of the volunteers who participated in this study.
TK, TA, and IY conceived and designed the study. HA, KW, and MK were involved in the research design. TA, TK, and IY conducted the experiments. TA, TA, and IY analyzed the data. TA wrote the manuscript. All authors read and approved the manuscript.
This study received no funding.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All experimental protocols were approved by the Medical Research Ethics Committee at Sapporo Medical University (approval number: 27-2-27).
The procedure, purpose, and risks associated with this study were explained to the subjects, and written informed consent was obtained.
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