It is claimed that weightlifting shoes with a raised heel may lead to a more upright trunk posture, and thus reduce the risk of back injuries during a barbell back squat. These proclaimed biomechanical effects have not been thoroughly investigated. The purpose of this study was to compare trunk and lower extremity biomechanics during barbell back squats in 3 foot postures.
14 recreational weightlifters (7 male and 7 female) between the ages of 18-50 performed barbell back squats in 3 conditions (barefoot on a flat surface, barefoot on a heel-raised platform, and wearing heel-raised weightlifting shoes) at 80% of their 1-RM. Surface electromyography (EMG) was used to assess the activation of the knee extensors and paraspinal muscles at L3 and T12 spinal levels. A 3D motion capture system and an electrogoniometer recorded the kinematics of the thoracic spine, lumbar spine, and knee during the back squat to a depth where the hip was at least at the same level to the knee.
Resultsindicated that none of the heel-raised foot postures significantly affected trunk and lower extremity muscle activation [thoracolumbar paraspinal (p=0.52), lumbar paraspinal (p=0.179), knee extensor (p=0.507)] or the trunk angles [thoracolumbar spine (p=0.348), lumbar spine (p=0.283)] during the squat.
Our results demonstrated that during barbell back squats, heel-raised foot postures do not significantly affect spinal and knee extensor muscle activations, and trunk and knee kinematics. Heel-raised weightlifting shoes are unlikely to provide significant protection against back injuries for recreational weightlifters during the barbell back squat.