The effect of wearing high-heels and carrying a backpack on trunk biomechanics

Abstract

Carrying a bag while wearing high-heels during daily life could potentially cause back pain. No study has investigated the combined effects of wearing a backpack and high-heels on trunk biomechanics from a system-level interaction viewpoint. Consequently, this study aimed to investigate the effects of high-heel height, backpack weight, and habituation in high-heels use on upper body biomechanics. Sixteen female study participants, all in their 20s, were divided into high-heel USER and NON-USER groups, and asked to carry a backpack with 0%, 5% and 10% of their body weight while either not wearing or wearing (0 cm and 9 cm) high-heels. Trunk kinematics and muscle activations were measured under the neutral standing posture while gazing straight ahead in experimental trials. First, the USERS tended to show hyper-lumbar lordosis when wearing high-heels, but the NON-USERS experienced lumbar kyphosis. In line with this, the USERS showed significantly greater recruitment of back muscles (35.5%), but the NON-USERS tended to recruit significantly more abdominal muscles (80%) to control their posture. Second, carrying a backpack sequentially induced posterior pelvic tilting, lumbar kyphosis, and forward head posture which is a stereotype posture of the hyper-kyphotic back and which suggests a system-level interaction from the lower extremity to the head. Third, the backpack weight eliminated the effect of wearing high-heels in the lumbar flexion angle, which may act as a counterbalance to pull the center of gravity (CoG) posteriorly.

Relevance to industry

Caution must be taken in the long-term use of high-heels and a backpack. Carrying a backpack weighing about 5% of the body weight is recommended to counterbalance the hyper-lordotic lumbar posture when wearing high-heels if unavoidable.