The Influence of Footwear with Different Sole on the EMG Activity of Lower Limb Muscle During Walking

This study examined the effect of the footwear sole flexibility on the lower limb muscle activity during normal walking. Thirty healthy adult males $(\text{mean age}: 30.93\pm 6.78)$ walk on 8.0 m walkway, while wearing three different kinds of shoes. The first shoe is flexible sole (the Skechers Elite flex - Aelhill Men's Sneakers Shoes, mass: 250 g), the second one is slightly-flexible sole (the Skechers Flex Advantage 3.0-Morwick, mass: 2803 g), and the third shoe is rigid sole (the Skechers Heston Rogic, mass: 680 g). During walking, the muscle activity of Gastrocnemius Medialis, Tibialis Anterior, and Vastus Medialis from both legs were recorded by electromyographic (EMG) via surface electrodes. Four experimental conditions were evaluated: (i) barefoot (BF), (ii) the flexible sole shoe (Shoe A), (iii) the slightly-flexible sole shoe (Shoe B), (iv) the rigid sole shoe (Shoe C). They repeated each those conditions four times. In this experiment, the muscle activity pattern of barefoot is used as the golden standard to compare with other individual muscle activity. The hypothesis is that the most flexible shoe should activate muscle activity pattern close to the barefoot muscle activity during normal walking. The repeated measures analysis of variance (RM-ANOVA) was conducted to analyze the different effects of each shoe condition. Results showed that significant differences happen for several statistical parameters such as peak, time of peak, duration of the peak, and onset time of peak amplitude for muscles: Gastrocnemius Medialis, Tibialis Anterior, and Vastus Medialis when comparing the four walking conditions. Since Barefoot is the baseline for this study, the conclusion is that onset time for tibialis anterior muscle pattern with Shoe A (Flexible Sole) was the closest pattern to the barefoot (BF) muscle activity during normal walking.