The effect of load in a floor-to-bench lift during the WorkHab Functional Capacity Evaluation

Abstract

BACKGROUND: 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.

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

METHOD: 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.

RESULTS: 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)].

CONCLUSIONS: 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.