STUDY DESIGN: Secondary analysis of a clinical trial. OBJECTIVE: To assess the impact of 6 months of arm cycle ergometry training (ACET), or body weight-supported treadmill training (BWSTT), on autonomic cardiovascular responses to a laboratory sit-up test (SUT) in individuals with chronic (>= 1-year post-injury) spinal cord injury (SCI). SETTING: Tertiary Rehabilitation Centre, Vancouver, Canada. METHODS: Sixteen individuals with motor-complete (American Spinal Injury Association Impairment Scale A-B) SCI between the fourth cervical and sixth thoracic spinal cord segments, aged 39 +/- 11 years, were assessed. Participants were randomized to receive 72 sessions of moderate-to-vigorous intensity ACET (n = 8) or passive BWSTT (n = 8). Changes in mean arterial pressure (finger plethysmography), hemodynamics (Modelflow R method), and heart rate/heart rate variability (HR/HRV; electrocardiography) were measured in response to a SUT before and after 6 months of exercise training. Spontaneous cardiovagal baroreflex sensitivity (cvBRS) was assessed using the sequence method. RESULTS: Neither ACET nor BWSTT impacted hemodynamic responses to SUT or the incidence of orthostatic hypotension (all p > 0.36). ACET increased HR (p < 0.01, etap2 = 0.34) and high frequency (HF) power HRV responses (p < 0.01, etap2 = 0.42) to SUT following 6 months of training while BWSTT did not. Consistent with this, cvBRS improved (p < 0.05, etap2 = 0.16) only following ACET. Improvements in cvBRS were correlated with both the HR (r = 0.726, p < 0.0001) and HF power (r = -0.484, p < 0.01) responses to SUT. CONCLUSION: Six months of ACET, but not BWSTT, improved cardiovagal baroreflex control of HR but had no effect on BP responses to SUT in individuals with chronic, motor-complete SCI. SPONSORSHIP: Canadian Institutes of Health Research (CIHR) CLINICAL TRIAL REGISTRATION: NCT01718977.
Reprinted by permission from Spinal Cord, Macmillan Publishers Ltd.

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