An unstable shoe with a rocker bottom redistributes external work

Abstract

The purpose of this study was to examine the external work performed by individuals wearing a rocker bottom shoe compared to a standard shoe. It was hypothesized that individuals wearing a rocker bottom shoe would have changes in the amount of work over the course of contact with the ground. External work on the body's centre of mass (BCOM) was calculated for individuals in both conditions. Comparisons for external work were done for positive and negative work for the entire stance phase as well as the initial double support, single support and terminal double support periods. The results revealed that while wearing the rocker bottom shoes, individuals performed an increased amount of negative work and decreased positive work in the initial double support followed by increased positive work in single support compared to a standard sole shoe. Individuals also performed a decreased amount of positive and negative work in terminal double support when wearing the rocker bottom shoes. There were no differences, however, when the stance phase was considered undivided to subphases for either positive or negative work. The results indicate that use of rocker bottom shoes redistributes external work to earlier in the gait cycle, which may not be as energetically efficient. This shift will probably result in increased metabolic energy expenditure as it will require more energy output from proximal hip musculature, which is not as mechanically efficient as the ankle joint in late stance. This could be desirable for individuals who are wearing the shoes for increased caloric burn such as an exercise setting. Furthermore, the increased external work in single support may be causing additional work from the hip extensor musculature (i.e. gluteus maximus). This could possibly be desirable for strengthening and conditioning of the hip extensors.