Reliability of the maximal aerobic power and ventilatory threshold in adults with cerebral palsy

This study examines the test-retest reliability of the ventilatory threshold (VT) and the maximum oxygen uptake (VO2max) in adults with cerebral palsy (CP). Nine subjects completed two continuous incremental tests on either a wheelchair ergometer (WE, n = 5) or a cycle ergometer (CE, n = 4) to volitional fatigue. Metabolic and cardiorespiratory responses were continuously monitored during the tests with an automated metabolic cart interfaced with an electrocardiogram. Two experienced evaluators identified the VT using standardized respiratory gas exchange criteria. The reliability coefficient for the VO2max during the two trials was significant (r = 0.83, p < .05). However, there was no significant relationship (p > .05) between the two trials for the oxygen uptake (VO2) at the VT identified by the two evaluators (r = 0.45 and 0.43). The correlations for this variable between the two evaluators were highly significant on each trial (r = 0.99 and 1.00, p < .01). No significant differences were observed between the two trials for the VO2 at the VT and the VO2max. These results suggest that when monitoring the cardiorespiratory fitness of adults with CP, it may be more appropriate to evaluate the VO2max rather than the VT, because the former variable can be reliably determined in these individuals whereas the latter lacks consistency.