The effect of load in a floor-to-bench lift during the WorkHab functional capacity evaluation

The safe maximal lift for a person is often determined during a functional capacity evaluation. This determination is based upon observation of unsafe lifting techniques, however there is limited information on specific kinematic changes that assist a therapist's clinical reasoning and determination of the safe maximal lift.

To evaluate any change in kinematics between safe minimum and safe maximum floor-to-bench lifts during the WorkHab Functional Capacity Evaluation.

Twenty-eight healthy participants (age range 18-22 years) were digitally recorded completing the evaluation. Lumbar spine, hip, knee and ankle joint angles were measured using Dartfish Pro-suite software at the beginning (0/3), one third (1/3), two thirds (2/3) and end (3/3) of the lift in descending and ascending phases. Paired t-tests were used to compare joint angles at each point of minimum and safe maximum lifts.

Significant changes in joint angles occurred lifting safe maximum weight compared to minimum weight. The lumbar spine was in greater flexion [4.9, 95% CI 2.1:7.7, p=0.001]; the knee joint was in less flexion descending [-4.5, 95% CI -8.1: -0.8, p=0.004 (3/3)] and ascending [-9.7, 95% CI -18.3: -1.16, p=0.027 (0/3)] and hip flexion increased at all points of the ascending phase (p⩽ 0.021). The ankle joint was in less dorsiflexion while descending [8.0, 95% CI 3.4:12.7, p=0.001(2/3); 6.7, 95% CI 4.4:9.0, p⩽0.001(3/3)] and ascending [8.9, 95% CI 6.24:11.6, p=0.001(0/3); 3.6, 95% CI 1.5:5.7, p⩽0.001(3/3)].

This study provides insight into kinematic changes and support observations made by the WorkHab assessor in determining a safe maximal lift during floor-to-bench lifts.