Electromyographic effects of foot orthotics on selected lower extremity muscles during running.
OBJECTIVE
To study the effects of foot orthotics on the mean electromyographic amplitude of proximal and distal lower extremity muscle groups during the first 50% of the stance phase during treadmill running.


METHODS
Repeated measures.


METHODS
Subjects were recruited from the general community.


METHODS
Twelve recreational runners who were symptomatic for lower extremity pain. Clinical and radiographic findings confirmed the presence of structural malalignment of the foot.


METHODS
Semirigid orthotics were fabricated for each subject, and like footwear provided.


METHODS
Surface electromyogram activity from the tibialis anterior, medial gastrocnemius, vastus medialis, vastus lateralis, and biceps femoris was collected during treadmill running at self-selected speeds for orthotic and nonorthotic conditions. Root mean square values were averaged across 10 cycles, normalized to time and expressed as a percentage of the nonorthotic condition.


RESULTS
Paired t test results showed statistically significant changes (p<.05) for the biceps femoris (-11.1%) and tibialis anterior (+37.5%) muscle groups during the orthotic condition. Electromyographic activity in the medial gastrocnemius, vastus medialis, and vastus lateralis with orthotic use was not significantly different from the nonorthotic condition.


CONCLUSIONS
Although subjects' electromyographic responses to orthotic use were highly individualized, the findings of this study may enhance our understanding of muscle activity changes associated with positive outcomes from orthotic use.
D000328:Adult; D004576:Electromyography; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007866:Leg / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D009989:Orthotic Devices; D012420:Running / Q000502:physiology*