Physiological correlates of simulated wheelchair racing in trained quadriplegics

This study examined the physiological responses during a 7.5-km simulated wheelchair race (SR) performed on rollers by 8 male quadriplegic marathon racers and analyzed the factors associated with SR time. Cardiac output (Q) was estimated during the SR using carbon dioxide rebreathing, from which stroke volume (SV) and (alpha-v)O2 diff were calculated. Subjects raced at 90 and 93% of peak oxygen uptake (VO2) and peak heart rate, respectively. SR time was inversely related (p < 0.05) to peak VO2, and VO2, Q, and SV during the SR, but not (alpha-v)O2 diff, age, and lesion level. Multiple regression analysis included only absolute SR VO2 in the equation to predict SR time: Y = -29.7X + 65.9; SE = 5.8. SR VO2 was significantly (p < 0.05) related to Q and SV but not to (alpha-v)O2 diff. These descriptive data suggest that SR performance in trained male quadriplegics might be limited by central, as opposed to peripheral, factors that determine VO2.