A Computational Simulation of Running Stability: Using the Spring Mass Model to Explore the Interaction of Body Weight and Shoe Softness

Abstract

Shoe softness is a crucial factor that influences people’s performance, comfort and potential risk of injuries while running, and directly affects the stability of running gait. While people with different body weights choose shoes with different levels of softness, how exactly the relationship between body weight and shoe softness plays a role in running is relatively overlooked. This study presents a computational model to investigate how body weight and shoe softness interact to influence the gait of running using the Spring Mass Model. As in this model, human leg is regarded as a compressible spring that provides rebound against the ground to support running, spring stiffness ( ) and body mass ( ) were respectively used to reflect shoe softness and body weight. Two experimental rounds were conducted via a Matlab simulator to simulate motion trajectories when running. In Round 1 where  was held constant and  varied, the results showed that excessively soft shoes (low ) caused the running gait to collapse and excessively stiff shoes (high ) would potentially lead to unstable running with too much rebound. In Round 2 where  was held constant and  varied, the results showed that on shoes that were identically soft, lighter runners experienced uncontrolled bouncing and heavier runners were more likely to experience collapse in running. To conclude, for people with different body weights, it is crucial for them to consider shoe softness accordingly in order to facilitate comfort and avoid fatigue and injuries when running. This study demonstrates how computational methodology can be utilized to inform human locomotion as well as footwear design and the broad scheme of physical health. Necessity to tailor shoe softness to different individuals was also enlightened.