The effect of lift teams on kinematics and muscle activity of the upper extremity and trunk in bricklayers.

STUDY DESIGN: Workplace-simulation study using a crossover design.

OBJECTIVES: To evaluate the effect of lift teams on trunk and upper extremity kinematics and muscle activity among bricklayers.

BACKGROUND: Healthcare practitioners often instruct individuals with work-related musculoskeletal disorders in proper lifting techniques. Bricklayers are especially affected by lifting-related musculoskeletal disorders. Lift teams are a possible intervention for reducing exposure to heavy lifting.

METHODS: Eighteen apprentice bricklayers constructed walls with concrete blocks alone (1 person) and in 2-person lift teams. Peak shoulder and trunk kinematics and normalized mean surface electromyography of the upper trapezius, lumbar paraspinals, and flexor forearm muscles were collected bilaterally. Differences between construction methods and rows 1, 3, and 6 of the wall were calculated with repeated-measures analyses of variance.

RESULTS: Working in lift teams required less trunk flexion (P = .008) at row 1 but more sidebending at row 6 (P<.001) than working alone. Dominant-side lumbar paraspinal activity was lower at row 3 (P = .008) among lift-team workers. Lift-team peak shoulder flexion was lower at row 3 (P = .002), whereas abduction was higher at rows 1 (P = .007) and 6 (P<.001). Concomitantly, nondominant upper trapezius activity and flexor forearm activity were significantly higher for lift teams at row 6 (P<.001 and P = .007). Block moment arm was significantly greater for lift teams at all rows (P≤.002).

CONCLUSION: Working in lift teams may be a beneficial intervention for reducing trunk flexion and lumbar paraspinal activity when bricklayers work at heights between the knees and waist, but lift teams are not recommended at higher working heights.