Kinematic and muscle activation differences in prolonged standing, transient low back pain and non-pain developers during tasks with functional demand and variety

Movement and muscle activity involving the lumbopelvic region differ between individuals who develop transient LBP during prolonged standing, compared to their pain-free peers. However, these findings involved low-demand tasks. Challenging task variations may elicit group differences previously unseen. This study examined kinematics and muscle activity in PDs and non-PDs during a variety of functional tasks with increased challenge. Thirty-nine subjects participated and were categorized for pain status. Kinematics and muscle activity were measured during five functional tasks: BEND, LIFT, MSTAR, AHA, and RSB. Certain tasks were made more challenging with an increase in external load and/or speed of performance. Kinematics, muscle sequencing, and muscle fatigue were analyzed with mixed-design ANOVAs. Only AHA revealed a pain status and task difficulty interaction effect with lower-limb kinematic variability. Different adaptations were evident in lumbopelvic control for this stratified cohort, which may be related to LBP development.