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. Design: Repeated measures. Setting: Subjects were recruited from the general community. Participants: Twelve recreational runners who were symptomatic for lower extremity pain. Clinical and radiographic findings confirmed the presence of structural malalignment of the foot. Intervention: Semirigid orthotics were fabricated for each subject, and like footwear provided. Main Outcome Measures: 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. Conclusion: 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.
Bibliographical noteFunding Information:
From the Department of Physical Therapy, Ithaca College-University of Rochester campus, Rochester, NY (Dr. Nawoczenski); and the Physical Therapy Program, Department of Physical Medicine and Rehabilitation, The University of Minnesota, Minneapolis, MN (Dr. Ludewig). This work was initiated while both authors were affiliated with the Graduate Program in Physical Therapy at The University of Iowa, Iowa City, IA. Submitted for publication August 17, 1998. Accepted in revised form November 12, 1998. Supported in part by the Foundation for Physical Therapy. Presented at the Annual Conference of the American Physical Therapy Association, June 1993, Cincinnati, OH. No commercial party having a direct financial interest in the results of the research suouorting I. this article has or will confer a benefit uoon the authors or upon any orzaniza&n with which the authors are associated. keprint requests to Deborah A. Nawoczenski, Associate Professor, Department of Physical Therapy, Ithaca College-University of Rochester campus, 300 E. River Road, Suite 1.102, Rochester, NY 14623. @ 1999 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation 0003-9993/99/8005-5169$3.00/O