Influence of Achilles Tendon Gear Length on Foot Gearing

The foot gear ratio is defined as the ground reaction force lever (R) divided by the Achilles tendon gear (r) and provides insight on how efficiently one lands and pushes off the ground. The gear ratio informs us about the load and mechanical efficiency of the foot and ankle. Typical biomechanical studies do not measure r directly and therefore to investigate foot gear ratios, new data is often required to be collected. Therefore, the purpose of this study is to determine if the length of r can be taken as a constant, or if it must be measured throughout time when calculating the foot gear ratio. Foot gearing calculations and data collection may be simplified if the length of r can be taken as a constant during movement tasks. Additionally, equations for estimating the length of r are investigated to determine the most appropriate method to use when r is not measured directly. This study will specifically look at the length of r during regular walking, fast walking, running, and drop vertical jump.