Responses of subjects with spinal cord injuries to maximal wheelchair exercise: comparison of discontinuous and continuous protocols.

Six male subjects with spinal cord injuries (SCI) participated in this investigation to compare peak values of oxygen uptake (VO2), heart rate (fc), ventilation (VE), respiratory exchange ratio (R) and power output (W) obtained using a discontinuous (DP) and a continuous jump max protocol (JMP) in a maximal wheelchair exercise test on a treadmill. The W increments were achieved by imposing an extra mass upon the wheelchair through a pulley system. The DP involved exercise periods of 3 min separated by 2-min intervals at relative rest. Increments in W consisted of 0.10 or 0.15 W.kg-1 total mass. During the rest intervals no mass was imposed on the wheelchair. The JMP involved an increase in W each minute. Increments and velocity in the JMP were the same as during the exercise periods for DP. Mean peak values for W [99.5 (SD 13.6) W], VO2 [2.13 (SD 0.27) l.min-1, standard temperature and pressure, dry], R [1.25 (SD 0.16)] and VE [82.8 (SD 11.2) l.min-1, body temperature and pressure, saturated] in DP were not different from values observed for W [103.5 (SD 13.1)], VO2 [2.18 (SD 0.31) l.min-1], R [1.17 (SD 0.16)] and VE [78.9 (SD 16.0) l.min-1] in the JMP. The only significant difference was observed for fc: 198 (SD 11) beats.min-1 in DP and 187 (SD 11) beats.min-1 in JMP. The higher values for fc elicited using DP have been discussed. It was concluded that both a DP and a JMP seem to be equally appropriate in determining peak VO2 and peak W in SCI persons.(ABSTRACT TRUNCATED AT 250 WORDS)