Running endurance abnormality in mdx mice

The mdx mouse lacks dystrophin and has histological features of Duchenne muscular dystrophy but little weakness in the first year of life. We report here an early deficit in voluntary wheel running, as assayed with a computerized wheel. All mdx mice showed an intermittent running pattern, in contrast to the continuous running seen in controls. The average continuous running time differed significantly between mdx and control mice at all ages tested (5-21 weeks). This assay is noninvasive, has the advantage of unbiased automatic data collection, and should be useful for quantifying the mdx deficit in therapeutic studies.