Abstract
Background: Nowadays, different types of exercise machines are being used in the field of athletic training, recreation, post-injury and post-operation rehabilitation. Leg press is a commonly-used one that retrains muscles and simulates natural functional activities. In this activity, feet are in contact with a footrest to exert muscular forces. In addition, the footrest inserts reactive forces to feet and from the feet load would transfer to structures that are more proximal. Any misalignment in foot structure may interfere its function. Objective: The aim of this study was to assess the effect of shoes and using a prefabricated medial arch support on the activity of Tibialis anterior and medial gastrocnemius muscles while doing leg press exercise in normal feet subjects. Method: 14 men with normal Medial Longitudinal Arch and normal Body Mass Index aged between 18-35 years old, with at least 6 months experience of doing leg press volunteered to participate in this study. Medial gastrocnemius and Tibialis anterior activity were measured by surface electromyography while doing leg press with 70% of subjects 1 Repetition Maximum. To increase accuracy, motion was divided into knee flexion and knee extension phases. Peak Amplitude, Time to Peak Amplitude and Root Mean Square variables were used for analysis. Wilcoxon nonparametric test was used to compare the results. Results: No statistically significant difference was found in the electromyographic parameters of Medial gastrocnemius nor Tibialis anterior in any phases of motion, except for an increase in Tibialis anterior time to peak amplitude in shod condition compared with barefoot in knee extension phase of motion (p-value=0.008) and Tibialis anterior RMS in knee flexion phase in orthotic condition compared to shod (p-value=0.03). Conclusion: It seems that in high loads shoes or medial arch supports cannot change electromyographic parameters in Medial gastrocnemius nor Tibialis anterior in any phase of motion while working with leg press device.
Highlights
Foot is one of the most important parts of the body that bears and distributes weight in close kinetic chain activities. This ability occurs through the complexity of its joints and its well-known Medial Longitudinal Arch (MLA) that has the ability to compress and recoil in response to different contact surfaces (Kelly, Cresswell, Racinais, Whiteley, & Lichtwark, 2014; Letafatkar, Zandi, Khodayi, & Vashmesara, 2013)
The results of current study demonstrated that wearing shoes or using a prefabricated medial arch support could not change Medial gastrocnemius and Tibialis anterior muscular activity in normal feet subjects while doing leg press
Time to peak increased in both studied muscles during knee flexion and knee extension phases in shod and prefabricated medial insole conditions in comparison with barefoot and in prefabricated medial insole condition compared to shoes alone
Summary
Foot is one of the most important parts of the body that bears and distributes weight in close kinetic chain activities This ability occurs through the complexity of its joints and its well-known Medial Longitudinal Arch (MLA) that has the ability to compress and recoil in response to different contact surfaces (Kelly, Cresswell, Racinais, Whiteley, & Lichtwark, 2014; Letafatkar, Zandi, Khodayi, & Vashmesara, 2013). Leg press is a commonly-used one that retrains muscles and simulates natural functional activities In this activity, feet are in contact with a footrest to exert muscular forces. Objective: The aim of this study was to assess the effect of shoes and using a prefabricated medial arch support on the activity of Tibialis anterior and medial gastrocnemius muscles while doing leg press exercise in normal feet subjects. Conclusion: It seems that in high loads shoes or medial arch supports cannot change electromyographic parameters in Medial gastrocnemius nor Tibialis anterior in any phase of motion while working with leg press device
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