The effect of pelvic position on popliteal angle achieved during 90:90 hamstring-length test.

CONTEXT Hamstring muscle length is commonly measured because of its perceived relationship to injury of both the hamstrings themselves and the pelvis and lumbar spine. The popliteal (knee-extension) angle measured from the starting position hip and knee at 90° is a commonly used indirect measure of hamstring muscle length. When this measure has been undertaken in the literature previously, little attention was paid to the position of the pelvis, which may significantly influence measurements taken. DESIGN Repeated-measures. SETTING University human performance laboratory. PARTICIPANTS 60 healthy physically active males (mean age 20.1 ± 1.8 y, range 18-24 y). INTERVENTION The 2 extremes of pelvic position (anterior and posterior). MAIN OUTCOME MEASURE Popliteal angle (with maximal knee extension) was measured in 2 positions, 1 of full anterior and 1 of full posterior pelvic tilt. RESULTS The mean difference in popliteal angle between anterior to posterior pelvic positions was 13.4° ± 9° (range 0-26°); this was statistically significant (P = .0001). CONCLUSION The findings of the study indicate that pelvic position has a significant effect on popliteal angle and therefore should be taken into account when measuring hamstring muscle length.