Restoration of Muscle Function During Rehabilitation

Many physiological conditions are associated with muscle weakness and can affect movement. This study will investigate which metabolic and morphological features of skeletal muscle are uniquely altered during the course of rehabilitation and how they affect muscle function and performance in daily ambulatory activities. This study will also examine how well the commonly used assessment measures reflect actual muscle capacity. Finally, because there is evidence that activity does not affect all fiber types uniformly, fiber-type specific metabolic and morphological measures will be performed.

Participants in this study will have had an ankle injury that has been treated surgically (Open Reduction Internal Fixation, or ORIF) followed by 5 to 10 weeks of cast immobilization. Following initial baseline measurements made after 1 week of re-ambulation, participants are enrolled in a 10-week rehabilitation program that focuses on restoration of both muscle strength and endurance. Assessments are made at Weeks 5 and 10 and include 31P-Magnetic Resonance Spectroscopy (MRS), Magnetic Resonance Imaging (MRI), muscle biopsy, and muscle function and functional performance tests. 31P-measurements monitor changes in the in vivo metabolic characteristics of skeletal muscle. 3D-MRI procedures will be used to quantify the maximal muscle cross-sectional area and total muscle volume. Muscle endurance and strength will be measured using an isokinetic dynamometer. Functional performance tests consist of self-selected walking pace, power for ascending and descending stairs, and toe raises while standing on one foot.

Nine participants (six patients and three control volunteers) will be studied each year. Control volunteers are submitted to the same measurements at similar time intervals in order to assess variability over time.