The missing Newton law in Podiatric Medicine

The first Newton’s laws of motion states that ‘A body at rest stays at rest, and a body in motion stays in motion, unless it is acted on by an external force’. This important law suggests that changing in speed of locomotion will cause a mechanical resistance by any mass. Consequently the persistence of speed fluctuation may cause a wearing effect on any involved mechanical component, which in turn will reduce its life time performance. Probably you have heard that it is better to drive with a constant speed to economize on gas consummation as well as increasing the life time of mechanical components. But do we have a similar phenomenon in Human motion?

Recent studies revealed that human brain controls inter-cycle gait variability during walking. In other words, even without paying attention, we have naturally a stable gait. This not only helps us to minimize the energy cost of locomotion but also helps to reduce the wearing of body joints. However gait steadiness may be challenged by several factors including joint deformity, pain, fatigue, cognitive disorders, as well as lost of foot sensation due to neuropathy. Designing an appropriate foot Orthotics may reduce the risk of gait unsteadiness and hence reducing risk of further complications such as back pain and osteoarthritis. Despite of this important fact, surprisingly a very little attention has been paid to gait variability in podiatry community.

Our students at Scholl’s College of podiatric medicine recently explored gait variability as a function of different Orthoses. Gait parameters were extracted using novel technology based on body worn sensors in free condition over a distance of minimum 100 feet. The purpose of the study was examining the effect of functional Orthoses versus Dr. Scholl’s prefabricated, over the counter Orthoses (OTC). Results revealed that although functional Orthoses may improve subject’s gait speed, it may also impact the subject gait inter-cycle variability, which increase energy cost and possible joint degeneration! Further investigation is required to assess whether this phenomenon is temporary and might be due to lack of footwear adaptation or the gait unsteadiness due to functional Orthoses is persistence and consequently may trigger other complications in long term.