Background Trunk flexion and extension have already been found to have different
characteristics, such as those in lumbopelvic rhythm. Although a more advanced method of
quantifying such rhythm, lumbopelvic continuous relative phase and phase variability have
not been used to explore the differences between trunk flexion and extension motions. This
information is important since abnormal lumbopelvic coordination patterns increase the risk
of low back pain. The current study investigated the differences in lumbopelvic rhythm …