Role of the interaction between lumbar kinematics and accelerometer-measured physical activity in bodily pain, physical functioning and work ability among health care workers with low back pain

The aim of this study was to examine the associations of spinal kinematics and physical activity (PA) with bodily pain, physical functioning, and work ability among health care workers with low back pain (LBP). Spinal kinematics and PA were measured with a wireless Inertial Measurement Unit system (ValedoMotion®) and a waist-worn tri-axial accelerometer (Hookie AM20), respectively. Their association was assessed in relation to Work Ability Index (WAI), bodily pain and physical functioning (RAND-36) in 210 health care workers with recurrent LBP. Greater lumbar movement variability/less deterministic lumbar movement (in angular velocity) during a “Pick Up a Box” functional task was correlated with higher amounts of step counts (r = -0.29, p = 0.01) and moderate PA (r = -0.24, p = 0.03). A higher amount of PA (p = 0.03) as well as less movement control impairment (p = 0.04) and movement variability (p = 0.03) were associated with greater work ability, whilst greater vigorous PA was the only parameter to explain higher physical functioning (p = 0.02). PA and movement variability were relative to each other to explain bodily pain (p = 0.01). These findings show the importance of considering the interaction between lumbar kinematics and physical activity while planning strategies to improve bodily pain, physical functioning and work ability among health care workers with LBP.