Effects of treadmill training on microvascular remodeling in the rat following spinal cord injury

Introduction: The morphological characteristics of skeletal muscles innervated caudal to a spinal cord injury (SCI) undergo dramatic phenotypic and microvascular changes.

Method: Female Sprague Dawley rats received a severe contusion at thoracic level 9/10, and were randomly assigned to locomotor training (TR), epidural stimulation (ES) or a combination of the treatment groups (CB). Fibre type composition and capillary distribution were assessed in phenotypically distinct compartments of the tibialis anterior.

Results: SCI induced a shift in Type II fibre phenotype from oxidative to glycolytic (P<0.05) as well as capillary loss within the oxidative core and glycolytic cortex; the CB treatment best maintained capillary supply within both compartments.

Discussion: The angiogenic response of CB training improved capillary distribution across the muscle, becoming spatially more homogeneous and decreasing mean capillary supply area, potentially improving oxygenation. There is an important role for weight bearing training in maintaining the oxidative phenotype of muscle following SCI.