Absence of cardiovascular drift during prolonged arm-crank exercise in individuals with spinal cord injury.

Abstract

Observational study OBJECTIVE: To investigate the effects of prolonged arm-crank exercise on cardiovascular drift (CV_drift) in spinal cord injury (SCI). This is a community-based supervision study METHODS: Ten participants with motor -complete or incomplete SCI (lesion level T7-L1), and 10 able-bodied (AB) participants matched for age performed a 40-min arm-crank exercise at an intensity of 50% of peak oxygen uptake (VO₂). During the exercise, there were no significant differences between the groups in VO₂, tissue O₂ saturation in the biceps brachii (active muscle), and chest and arm skin temperature (all P > 0.05). In the AB, heart rate (HR) increased within the first 15 min of the exercise and continued to increase until the end of the exercise; however, in the SCI, HR increased within first 15 min of the exercise and then remained constant until the end of exercise. After 10 min of exercise, thigh skin temperature had increased more in the SCI than in the AB (P < 0.05). Thigh skin blood flow (SkBF) continued to increase after 10 min of exercise in the AB but remained almost stable in the SCI. Relative changes in the thigh SkBF were associated with changes in HR during exercise between the values at 10 min and 40 min in the pooled data (R² = 0.706, P < 0.001). CV_drift during the prolonged arm-crank exercise was not observed in individuals with SCI. This might be partially explained by different responses in cutaneous circulation within the inactive muscles of these participants.