Investigation on the measurement sites of the cross-sectional areas of the gluteus maximus and gluteus medius.

PURPOSES: To verify the relationship between muscle volume and muscular strength of different cross-sectional areas (CSAs) of the gluteus maximus and medius, and to clarify the effective evaluation index. METHODS: Twenty healthy adults were enrolled in this cross-sectional study. Magnetic resonance images were evaluated, and CSAs of the gluteus maximus and medius were calculated. Calculation sites were the peak CSA, lowest end of the sacroiliac joint CSA, and just above the femoral head CSA. Muscle volume and muscular strength were measured. The correlation between muscular CSA, muscle volume, and muscular strength was verified using Pearson's correlation coefficient (p < 0.05). One-way analysis of variance and the Tukey-Kramer test were used to verify differences in each CSA (p < 0.05). RESULTS: A significantly positive correlation was found between muscular CSA, muscle volume, and muscular strength of both muscles (p < 0.05). For the gluteus maximus, the muscular CSA calculated just above the femoral head showed a significantly larger value than that calculated at the lowest end of the sacroiliac joint (p < 0.05). For the gluteus medius, the peak CSA and muscular CSA calculated at the lowest end of the sacroiliac joint were significantly larger than that calculated just above the femoral head (p < 0.05). CONCLUSIONS: The maximum CSA of the gluteus maximus was found just above the femoral head and that of the gluteus medius was near the lowest end of the sacroiliac joint; hence, CSAs should be calculated at these sites. The CSA reflected muscle volume and strength.