Metabolic and cardiopulmonary responses to acute progressive resistive exercise in a person with C4 spinal cord injury

Abstract

Study Design: Single-subject (female, 38 years of age) case. Objectives: To describe metabolic and cardiopulmonary responses to progressive resistive exercise in an individual with C4 ASIA A tetraplegia, and to review the relationship between level of spinal cord injury (SCI) and exercise responses. Setting: Large, urban mid-western city rehabilitation hospital in United States of America. Methods: Bilateral shoulder elevation/depression (shoulder shrug) exercise with two different resistances (0.7 kg/shoulder, 1.4 kg/shoulder) at two different frequencies (20 min., 40 min.), for 2 min per bout, deployed in a discontinuous protocol. Results: Compared to rest heart rate (HR), exercise HR increased the greatest (13 bpm) for the 1.4 kg resistance at 40 min. and the least (6 bpm) during the 0.7 kg at 20 min. Blood pressure (BP) response was lower than resting BP for all four exercise conditions with the lowest (74/56 mmHg) at 1.4 kg at 40 min. Oxygen uptake was highest (4.6 ml.kg-1 min-1) during 1.4 kg at 20 min and VE was greatest (18.2 L/min) during 1.4 kg at 40 min. Rate of perceived exertion (RPE) was the highest (17) during the 1.4 kg at 40 min. Conclusions: Progressive resistance exercise provoked intense perceived physical effort, but only small metabolic and cardiopulmonary increases in a person with C4 SCI. Exercise recommended at a 'somewhat hard' intensity should avoid significant hypotension and still impressively increase oxygen uptake and ventilation compared to rest. An inverse relation between level of injury and aerobic responses may extend rostrally to the C4 level.