Compared with barefoot walking, a standard flexible shoe and stability running shoe significantly altered electromyographic activation of leg muscles in individuals with flat-arched feet. Their wear demonstrated a similar pattern of lower leg muscle activity in adults walking short distances in either type of shoe, according to a recently published study.

“Over the last two decades, the construction of athletic footwear has evolved dramatically to now include a range of materials with properties that are thought to support and cushion the lower limb to assist with locomotion,” the researchers wrote in the Journal of Electromyography and Kinesiology. “It is not possible to generalize findings of current research to individuals who use stability running shoes for activities of daily living. Accordingly, it is unknown whether stability running footwear systematically alters lower limb muscle activity during walking, compared to standard, less supportive footwear. The aim of this study was to compare lower limb muscle activity during walking in people with excessively pronated feet whilst wearing a commercially available stability running shoe and a standard flexible shoe compared to a barefoot condition.”

Muscle activity assessment

Researchers recruited 28 young asymptomatic adults with flat-arched feet who were assessed while walking barefoot with a standard flexible shoe and with a stability running shoe. Electromyographic (EMG) activity was recorded from the tibialis posterior and peroneus longus muscles via intramuscular electrodes and from the tibialis anterior and medial gastrocnemius muscles via surface electrodes while walking.

According to the results, peak amplitude significantly increased in the tibialis anterior with both shoe conditions vs. walking barefoot and occurred temporally earlier with the flexible shoe condition compared with walking barefoot. Medial gastrocnemius peak amplitude also significantly increased with the running shoe condition vs. walking barefoot, but was temporally delayed with the running shoe compared with walking barefoot and the flexible shoe conditions. Study results showed that, with both shoe conditions, peroneus longus peak amplitude was reduced compared with walking barefoot and occurred temporally earlier with the running shoe condition compared with walking barefoot.

“There were no significant findings detected for tibialis posterior comparing the footwear and barefoot conditions. This was surprising because tibialis posterior is regarded as a dynamic invertor and stabilizer of the medial longitudinal arch and in those with a pronated foot posture there is evidence to suggest this muscle has greater EMG activation during walking,” George S. Murley, PhD, of the Department of Podiatry and the Lower Extremity and Gait Studies Program at La Trobe University in Australia, told O&P Business News. “Therefore, we expected the stability running shoe to decrease EMG amplitude of tibialis posterior as a result of the support/bracing features incorporated into the shoe (ie, rigid heel counter and dual density midsole); however, this was not detected in the results.”

Limitations and future studies

The researchers acknowledged that the stability running shoe is designed for running gait rather than walking, and that the study should be retried under running conditions. They also recognized that the study did not include an extended habituation period for participants to adjust to the two styles of footwear and no data was collected on participants’ level of physical activity or chosen sport.

Although the results of this study may contribute to understanding how footwear influences lower limb biomechanics, according to Murley, these results do not have any clinical implications since they investigated asymptomatic individuals.

“Individuals with flat-arched feet display a similar pattern of lower leg muscle activity when they are walking short distances in either stability or casual/flexible shoes,” Murley said. “Further research, such as clinical trials, is required to explore the effects of stability and motion control footwear on lower limb muscle activity and in symptomatic participants with musculoskeletal pathology.”— by Casey Murphy

For more information:
Scott LA. J Electromyogr Kinesiol. 2012;22:1010-1016.

Disclosure: The study was supported by the Australian Podiatry Education and Research Foundation.

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