The effect of abdominal muscle strengthening on pelvic tilt and lumbar lordosis

The purpose of this study was to examine the effects of abdominal strengthening on pelvic tilt and lumbar lordosis in healthy subjects with established abdominal weakness, in a relaxed standing position. Data were collected on 20 subjects, before and after an 8 week abdominal muscle strengthening programme. Abdominal muscle strength was tested using a modification of Kendall's leg-lowering test, pelvic tilt was measured using a pelvic inclinometer, and lumbar lordosis was measured using a flexible ruler. Twenty control subjects were used to determine reliability of the measurements over the 8 week period. The intra-class correlation coefficients calculated for measures of pelvic tilt, lumbar lordosis and abdominal strength were 0.87, 0.96 and 0.55 respectively, demonstrating reliability of these measures over the 8 week period. In the subsequent ANCOVA, controlling for pre-test scores, post-test mean muscle strength in the experimental group was found to be significantly greater than in the control group. However, there were no differences in mean post-test pelvic tilt or lumbar lordosis between the groups. Based on the results of this study, the clinical practice of strengthening the abdominal musculature to affect change in lumbar lordosis and pelvic tilt in standing posture needs to be reconsidered.