Rehabilitation research in children with cerebral palsy (CP) is increasingly addressing cardiorespiratory fitness testing. However, evidence on the reliability of peak oxygen uptake (V̇o2peak) measurements, thought to be the best indicator of aerobic fitness, is unavailable in this population. This study’s aim was to establish the reliability of a progressive maximal cycle ergometer test when assessing V̇o2peak in children with mild to moderate CP. Repeated measures were used to assess test-retest reliability. Eligible participants were ambulant, 6 to 14 years of age, and classified as level I, II, or III according to the Gross Motor Function Classification System (GMFCS). Two progressive maximal cycle ergometer tests were conducted (separated by 3 weeks), with the workload increasing every minute in steps of 3 to 11 W, dependent on height and GMFCS level. Reliability was determined by means of the intraclass correlation coefficient (ICC [2,1]) and smallest detectable change (SDC). Twenty-one children took part (GMFCS I: n=4; GMFCS II: n=12; and GMFCS III: n=5). Sixteen of them (9 boys, 7 girls; GMFCS I: n=3; GMFCS II: n=11; and GMFCS III: n=2) performed 2 successful tests, separated by 9.5 days on average. Reliability for V̇o2peak was excellent (ICC=.94, 95% confidence interval=.83–.98). The SDC was 5.72 mL/kg/min, reflecting 14.6% of the mean. This study was limited due to the small sample size, which did not allow separate analysis of reliability per GMFCS level.
This study found that in children with CP of GMFCS levels I and II, a progressive maximal cycle ergometer test to assess V̇o2peak is reliable and has the potential to detect change in cardiorespiratory fitness over time. Additional study is required to establish the reliability of V̇o2peak in children of GMFCS level III.