Validation of shuttle tests in children with cystic fibrosis

Shuttle tests are simple, inexpensive field tests that have been used to estimate the cardiorespiratory status of children. It has yet to be validated in children with CF. The aim of this study was to assess the reproducibility and criterion validity of shuttle tests in children with cystic fibrosis (CF). Ninety-three CF patients aged 6 to 16 years of age with a wide range of disease severity performed the study. The 10-m shuttle test was used for children 7 years of age and younger and those deemed too chronically ill by their physicians to perform the longer test (n = 35.) All other children performed the 20-m shuttle test (n = 58). Reproducibility and criterion validity were assessed for each child over a two week period. Gas analysis was performed throughout testing using a polargraphic gas analyzer. The 10-m shuttle tests were reproducible (mean difference between tests VO(2) 2.41 mL/kg/min, CI 3.46,-0.18) and the difference from treadmill testing was not statistically significant (mean difference VO(2) 5.30 mL/kg/min, CI-7.46, 1.18). The 20-m shuttle tests were reproducible (mean difference between tests VO(2) 2.07 mL/kg/min, CI-3.90,0.60) and the difference from treadmill testing was not statistically significant (mean difference VO(2) 3.50 mL/kg/min, CI-4.90, 1.60). We conclude that when formal exercise testing with treadmill or cycle ergometer cannot be performed, the shuttle tests provide a reproducible and valid alternative.