The effect of load on biomechanics during an overhead lift in the WorkHab Functional Capacity Evaluation

Objective: The role of biomechanics during the overhead lift has not been widely investigated. This study aimed to evaluate any change in biomechanics between safe minimum and safe maximum overhead lifts during the WorkHab Functional Capacity Evaluation. Method: Thirty healthy participants (age range 18–22 years) were videotaped completing the overhead lift. Images at the beginning (0/3), one-third (1/3), two-thirds (2/3), and end of lift (3/3) were collected for the minimum and safe maximum lifts Measurement of joint angles of the wrist, elbow, shoulder and sagittal spine using Dartfish Prosuite software was completed. Paired t-tests were used to analyse the differences in joint angles between lifts. Results: Participants' biomechanics changed between the minimum and maximum lifts In comparison to minimum lifts, there was increased wrist ulnar deviation (10.50, 95% CI 4.39, 16.61, p=0.002), increased shoulder flexion (7.26, 95% CI 0.50, 14.01, p=0.036), increased thoracic extension (−3.40, 95% CI −5.36, −1.45, p=0.001), increased lumbar extension (3.75, 95% CI 1.39, 6.12, p=0.003), and decreased elbow flexion (−11.28, 95% CI −18.57, −4.00, p=0.004) in the maximum lifts. Conclusions: The results of this study provide insight into biomechanical changes during the overhead lifting, and support the clinical judgements made by the WorkHab assessor in determining safe maximal lift.