In this study, we analyzed the correlations between hip flexion power, sprint performance, lumbar lordosis (LL) and the cross-sectional area (CSA) of the psoas muscle (PM). Ten young adults performed two sprint tests and isokinetic tests to determine hip flexion power. Magnetic resonance imaging was used to determine LL and PM CSA. There were correlations between hip flexion power, sprint performance, and PM CSA, but LL showed no correlation with any parameter. The impact of hip flexion power and LL on sprint stride pattern efficiency was considered. Hip flexion might not have a simple role in the passive knee replacement of the stride pattern; instead, it may be an active parameter. Other investigations are needed to determine the influence of pelvic architecture on sprint performance. (Contains 3 tables and 4 figures.)