EFFECT OF RESTRICTED HIP FLEXOR MUSCLE LENGTH ON HIP EXTENSOR MUSCLE ACTIVITY AND LOWER EXTREMITY BIOMECHANICS IN COLLEGE-AGED FEMALE SOCCER PLAYERS.
Level 4 - case-series / case-control
Cross-sectional comparative study evaluating neuromuscular parameters across two predefined anatomical groups.
What was done
Forty college-aged female soccer players were classified into two groups based on a modified Thomas Test: restricted hip flexor length (>0° above horizontal, n=20) or normal length (>15° below horizontal, n=20). Surface electromyography (sEMG) of the gluteus maximus and biceps femoris, along with internal hip and knee extension moments, was measured during a double-leg squat. Isometric gluteus maximus strength was evaluated using handheld dynamometry.
What was found
Athletes with restricted hip flexor length demonstrated significantly lower gluteus maximus sEMG activation (p = 0.008) and a reduced gluteus maximus to biceps femoris co-activation ratio (p = 0.004) compared to controls. No significant differences (p > 0.05) were found between groups for net internal hip or knee extension moments, biceps femoris activation alone, or isometric gluteus maximus strength. Absolute numerical means and variances for sEMG and joint moment measures were not reported in the abstract.
Why it matters
These findings suggest that hip flexor tightness is associated with altered neuromuscular coordination strategies during bilateral squatting, partially supporting theories of reciprocal inhibition and synergistic dominance.
Limits
The study is restricted to a small cohort of female collegiate soccer players, limiting generalizability to males, older adults, or other athletic populations. The cross-sectional design cannot establish whether hip flexor tightness caused the altered activation patterns or whether these neuromuscular differences lead to increased injury risk in dynamic sports tasks.
Cited by
- context Due to reciprocal inhibition, squeezing the left glute signals the right hip flexor to turn off, increasing range of motion.