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

Study Design: Single-subject (female, 38 years of age) case. Objectives: To describe metabolic and cardiopulmonary responses to progress ive resistive exercise in an individual with C4 ASIA A tetraplegia, and to review the relationship between level of spinal cord injury (SCI) and exerc ise responses. Setting: Large, urban mid-western city rehabilitation hospital in United St ates of America. Methods: Bilateral shoulder elevation/depression (shoulder shrug) exercise with two different resistances (0.7 kg/shoulder, 1.4 kg/shoulder) at two di fferent frequencies (20 min., 30 min.), for 2 min per bout, deployed in a d iscontinuous protocol. Results: Compared to rest heart rate (HR), exercise HR increased the greate st (13 bpm) for the 1.4 kg resistance at 40 min. and the least (6 bpm) duri ng the 0.7 kg at 20 min. Blood pressure (BP) response was lower than restin g BP for all four exercise conditions with the lowest (74/56 mmHg) at 1.4 k g at 40 min. Oxygen uptake was highest (4.6 ml.kg(-1) min(-1)) during 1.4 k g 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 mi n. Conclusions: Progressive resistance exercise provoked intense perceived phy sical effort, but only small metabolic and cardiopulmonary increases in a p erson with C4 SCI. Exercise recommended at a 'somewhat hard' intensity shou ld avoid significant hypotension and still impressively increase oxygen upt ake and ventilation compared to rest. An inverse relation between level of injury and aerobic responses may extend rostrally to the C4 level.