Comparison of physiological responses to maximal arm exercise among able-bodied, paraplegics and quadriplegics

A comparison of pulmonary, cardiovascular and metabolic responses was made in 32 subjects consisting of 11 able-bodied, 8 paraplegics (T4-L3 lesions) and 13 quadriplegics (C5-C8 lesions) during maximal arm cranking exercise. A progressive continuous arm cranking test, modified for each group, was employed to elicit maximal responses with pulmonary and metabolic determinations made with open circuit spirometry and selected cardiovascular measurements made by impedance cardiography. Additionally, non-exercise static and dynamic lung function assessments were made. Quadriplegics had significantly lower (p less than 0.05) tidal volumes, vital capacities, forced expiratory volumes at 1 seconds, and maximal breathing capacities than the other two groups. The mean peak VO2 during maximal arm cranking was 28.2, 25.3 and 12.0 ml/kg.min for the able-bodied (AB), paraplegics (PP) and quadriplegics (QP), respectively. Furthermore, reduced cardiovascular function was observed in the QP as evident in the low peak HR (109 b/min), peak SV (52 ml/b) and peak Q (5.7 l/min). Values for the QP were 64% and 64% peak HR, 89% and 50% peak SV and 54% and 33% peak Q of values observed for the PP and AB groups, respectively. The peak SV and Q values were significantly lower (P less than 0.05) for the PP group when compared with the AB group. Although not statistically significant the estimated a-v O2 difference was higher for both spinal cord injured groups (14.0 and 14.6 ml O2/100 ml, PP and QP respectively). The impaired work capacity and reduced oxygen transport and utilisation of the QP group can be attributed to impaired sympathetic cardiac stimulation and a smaller available active muscle mass.