Relationship between pelvic floor muscle function and changes in lumbar spine and hip motion due to pelvic floor muscle contraction

BACKGROUND: Pelvic floor muscles (PFM) are important for lumbar stability. However, the relationship between lumbar and hip motion angle changes (MAC) caused by PFM contraction and each PFM's function remains unclear. OBJECTIVE: To clarify the lumbar spine and hip motion changes produced by PFM contraction and the relationship between MAC and PFM function. METHODS: In 21 healthy females, motion angle was measured for prone hip extension movement using natural movement (NM), PFM contracting movement (PM), and reducing lumbar movement (RM) methods. The PFM functional indices were bladder base elevation distance, continuous bladder base elevation time, and pelvic floor location. RESULTS: The PM showed no significant difference in lumbar motion angle but had significantly smaller hip motion than the NM (NM; 26.1 +/- 8.3, PM; 29.2 +/- 11.0). MAC was significantly greater in RM (lumbar spine; 4.4 +/- 3.2, hip; 5.9 +/- 8.7) than in PM (lumbar spine; 0.4 +/- 4.4, hip; 3.1 +/- 5.1) for both the lumbar spine and hip. Lumbar spine and hip MAC of PM was significantly correlated with pelvic floor location (lumbar spine; r = -0.44, hip; r = 0.54). CONCLUSION: PFM contraction does not attenuate lumbar spine motion but reduces hip motion. MAC due to PFM contraction during lumbar movement tasks is related to the PFM functional index.