Rapid vascular adaptations to training and detraining in persons with spinal cord injury.

OBJECTIVE: To assess the time course of arterial adaptations during 6 weeks of functional electric stimulation (FES) training and 6 weeks of detraining in subjects with spinal cord injury (SCI).

DESIGN: Intervention study (before-after trial).

SETTING: University medical center.

PARTICIPANTS: Volunteer sample of 9 subjects with SCI.

INTERVENTIONS: Six weeks of twice weekly FES cycling and 6 weeks of detraining.

MAIN OUTCOME MEASURES: Vascular characteristics were measured by plethysmography (baseline and peak blood flow of the thigh) and echo Doppler (diameter of the femoral artery and flow-mediated dilation [FMD]).

RESULTS: After 2 weeks of FES training, arterial characteristics changed significantly; there was an increase in baseline and peak blood flow, an increase in femoral artery diameter, and a decrease in FMD of the femoral artery. Detraining reversed baseline and peak thigh blood flow, vascular resistance, and femoral diameter toward pretraining values within 1 week. However, detraining did not restore the FMD of the femoral artery, even after 6 weeks.

CONCLUSIONS: Two weeks of hybrid FES training (4 exercise bouts) is sufficient to improve peak leg blood flow and arterial diameter, and to normalize FMD. In addition, detraining results in rapidly reversed vascular characteristics within 1 week.