Background and aims
“Lifting an object with a round back is dangerous!” This is a widespread belief among the general public, which might influence an individual’s lifting technique. We therefore aimed at investigating the relationship between the perceived threat value of lifting with a round back and lumbar spine motion during repetitive lifting maneuvers.
Twenty pain-free adults (mean age=32.4y, 12 females) completed the Photograph-Daily-Activities-Series-Short-Electronic-Version (PHODA-total), including pictures showing a person lifting a flowerpot with a round- and straight back (PHODA-round-back and PHODA-straight-back, respectively). Subsequently, participants were equipped with 58 retro-reflective markers and asked to lift a 5kg-box. Marker data were collected with a 20-camera optical-motion-capture system and used to calculate sagittal spinal curvature angles. To investigate the relationship between PHODA scores (0 ‘Not harmful at all’,100 ‘Extremely harmful’) and kinematics, linear regression analyses were carried out using one-dimensional Statistical-Parametric-Mapping (alpha-level=0.05).
Mean scores were 20.68(SD=±13.87) for PHODA-total, 13.95(SD=±11.39) for PHODA-straight-back and 43.1(SD=±27.21) for PHODA-round-back, respectively. Linear regression analysis revealed a negative relationship between the PHODA-round-back score and lumbar curvature angles during 0-72% of the lifting-up (-0.53≤r≥-0.57,p=0.010) and 28-73% of the putting-down cycles (-0.52≤r≥-0.54,p=0.026). No relationships were found for PHODA-total and PHODA-straight-back scores.
Healthy adults with “round back danger” beliefs demonstrated less lumbar spine flexion during distinct time periods of the lifting maneuver, potentially driven by lumbar stiffening. This might predispose these individuals for a lumbar stiffening strategy when they experience low back pain, potentially aggravating symptoms through pronociceptive triggers such as increased paraspinal tissue loading and muscle fatigue.