Changes of Lumbar Muscle Flexion Relaxation Phenomenon When Standing on Unilaterally Elevated Ground

Occupational tasks performed on uneven ground surfaces are common in agriculture and construction industries. The influence of unilaterally elevated ground surface on lumbar muscle flexion relaxation phenomenon (FRP) during trunk flexion and extension motion has been investigated in the current study. Ten subjects performed trunk flexion and extension motion on flat ground and two unilaterally elevated ground conditions while lumbar muscle EMG and trunk kinematics data were recorded. Results of this study demonstrated clear difference in bilateral lumbar muscle FRP under elevated ground conditions. The current finding can be used to better understand uneven ground surfaces as a risk factor for the development of low back pain.