The Effects of Hip Abductor and External Rotator Strengthening on Pelvic Position in ‎Frontal Plane in Men with Dynamic Knee Valgus During Single-leg Landing

It has been theorized that contralateral pelvic drop indicates weakness of the stance hip-abductor and external rotator musculature, results in impaired load transfer, which may contribute to lower extremity injuries. In spite of the relationship between hip weakness and pelvic tilt, unfortunately few studies have been investigated the effect of hip strengthening on pelvic position. Therefore, the purpose of the present study was to investigate the effect of hip abductor and external rotator strengthening on pelvic position in frontal plane during single-leg landing.  

Thirty-two males with knee valgus angle more than 8 degree were selected through non-probability inconvenient sampling and randomized into an experimental (n=16, age: 22.35 ± 1.82 year, height: 1.78 ± 0.07 meter, weight: 70.92 ± 11.6 kg) and control groups (n=16, age: 22.66 ± 1.79 year, height: 1.8 ± 0.05 meter, weight: 71.01 ± 11.61 kg). The experimental group carried out 8 weeks of bilateral hip abductor and external rotator strengthening 3 times per week (each session 45-60 minutes) and control group continue to daily activity as usual. Pre and post-tests hip strength were measured with isokinetic dynamometer (Kin-Com) and motion capture data were collected during 3 single-leg landing trials before and after training. Pelvic tilts were estimated using QTM and Visual 3D software. Data were analyzed via SPSS software applying the repeated measures ANOVA at a significant level of p < 0.05.

Significant group-by-time interactions were observed for concentric and eccentric hip abduction (p < 0.001, p < 0.001) and external rotation (p < 0.02, p < 0.001) strength and upward pelvic tilt (p=0.047) and range of motion of pelvic drop (P=0/005), respectively. Post hoc testing revealed that concentric and eccentric hip abductor (p < 0.001, p=0.004) and external rotator (p=0.01, p < 0.001) strength increased and upward pelvic tilt (P=0.04) and range of motion of pelvic drop (p=0.008) respectively, decreased in the experimental group following the 8-week intervention but did not change in the control group (p> 0.05).

An eight week hip abductor and external rotator strengthening programs was effective in improvement concentric and eccentric hip abductor and external rotator strength and pelvic position in frontal plane.