Protocol dependency of VO2max during arm cycle ergometry in males with quadriplegia

The purpose of this study was to determine whether maximal oxygen uptake (VO2max) is protocol dependent during arm cycle ergometry (ACE) for quadriplegic males with spinal cord injuries (SCI). Twenty-four non-ambulatory subjects (aged 20-38 yr) with cervical SCI were divided into two groups based on wheelchair sports classification (IA group = 14; IB/IC group = 10). They underwent three different, continuous graded exercise tests spaced at least 1 wk apart on an electronically braked arm cycle ergometer. Following a 3-min, unloaded warm-up at 60 rpm, the work rate was increased 2, 4, or 6 W.min-1 for the IA group and 4, 6, or 8 W.min-1 for the IB/IC group. Ventilation and gas exchange were measured breath-by-breath with a SensorMedics 4400 computerized system. Repeated-measures ANOVA showed no significant difference among the three protocols for VO2max in the IA group (P greater than 0.05). The mean (+/- SD) VO2max values (ml.kg-1.min-1) were 10.8 (+/- 3.4), 11.0 (+/- 2.7), and 10.2 (+/- 2.9) for the 2, 4, and 6 W.min-1 protocols, respectively. In contrast, the IB/IC group showed a significant difference among the protocols for VO2max (P less than 0.05). The mean (+/- SD) VO2max values (ml.kg-1.min-1) were 16.8 (+/- 4.5), 15.3 (+/- 4.3), and 14.6 (+/- 4.3) for 4, 6, and 8 W.min-1, respectively. Post hoc analysis revealed a difference between the 4 and 8 W.min-1 protocols. Our results suggest that graded exercise testing of SCI persons with quadriplegia, using ACE, should employ work rate increments between 2-6 W.min-1 and that work rate increments of 8 W.min-1 or greater will underestimate VO2max.