Decreased task duration and unchanged trunk muscle activity in low-back pain patients during stair climbing after back extensor muscle fatigue

Low-back pain (LBP) is a major problem. Spine control and stability mechanisms are important but the knowledge of these parameters in functions is sparse.
7 healthy / 5 recurrent mild-to-moderate LBP patients participated in assessment of abdominal, lumbar and gluteal muscles' surface EMG and video recording during 10 concurrent stair steps pre / post lumbar extensor muscle exhaustion.
Duration of gait tasks were shorter in LBP patients generally and longer during load and shorter during transfer in descend stepping after back extensor fatigue.
Back extensor fatigue resulted in higher back- and abdominal muscle activity in healthy than in patients in most phases, but during descend transfer patients activity decreased.
In LBP patients back extensor fatigue resulted in decreased muscular activity in the trunk muscles during stair stepping compared to healthy. Decreased duration of the motor tasks generally could indicate decreased functional stability and during descend transfer with high stability demands, LBP patients could be at higher risk of load to the lumbar structures.
Affected control of the spine in high stability demands could be important in evaluation of recurrent LBP, but more research is needed to explore the mechanisms and the potential role in LBP development.