Effects of asymmetric trunk muscle fatigue on pelvic inclination and rotation

Although the influence of muscle activity on the pelvic position has been proven, research on the influence of (asymmetric) muscle fatigue on the pelvic position is inconsistent. The purpose of the present study was to assess the effects of asymmetric fatigue of the lateral trunk muscles on the pelvic position based on a pre/post/follow-up design. For the final data analysis, 38 subjects (20 men, 18 women; age 22.63 ± 3.91 years) were asked to perform side bends in sets of 20 repetitions on a Roman chair until complete exhaustion. For pre-, post-, and follow-up test (24 h after treatment), pelvic positions were recorded with a 3D photogrammetric scan. Statistical analysis showed no systematic changes in pelvic inclination and rotation after unilateral exhaustion for the three measuring times. However, highly individual, non-systematic changes in pelvic positions were present, especially between pre- and post-test. The follow-up measurements tend to return to the initial pre-test state. Unilateral fatigue of the lateral flexors of the trunk affects the pelvic position in a non-systematic way.