Effects of Sex, Lift Origin, Handedness, and Normalization on Spinal Loads in Maximal Box Lifting With Risk Assessment

The objectives of this work were to investigate the influence of sex, handedness, and lift origin and their interactions on peak lumbar moments and loads at the L5–S1 disc level during maximally loaded box lifting tasks, examine how different normalization techniques can affect these results, and perform a risk assessment of maximum lifting where individuals self‐select a safe maximum weight to lift. Twenty participants (sex, 10 women and 10 men; handedness, 10 left‐dominant and 10 right‐dominant) performed individualized maximally weighted box lifts from five lift origins. The OpenSim Lifting Full‐Body Model was used to predict peak lumbar moments and loads. Box lift origin had a consistent influence on peak lumbar moments and loads at the L5–S1 disc level during maximally loaded box lifting tasks, where symmetric lifts produced higher lumbar flexion moments, compression loads, and shear loads than asymmetric lifts. Handedness did not have a consistent influence on peak lumbar moments or loads. Sex consistently influenced lumbar loading, with men experiencing higher lumbar loads than women. It was determined that normalization techniques can alter statistical findings, which can lead to misinterpretations if the approach does not ensure a direct comparison between groups. The risk assessment of maximum lifting revealed that a large percentage of the lifts exceeded the recommended thresholds established in the literature, indicating that individuals are unlikely to self‐select a safe maximum weight to lift.