Sarah P Cohen1, David M Orenstein2. 1. University of Pittsburgh School of Medicine, 5806 Ellsworth Ave #1, Pittsburgh, PA 15232, United States. 2. Department of Pediatrics, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC, United States. Electronic address: davido@pitt.edu.
Abstract
BACKGROUND: Disease progression in cystic fibrosis (CF) is marked by worsening exercise tolerance. Further, maximal exercise capacity (VO2 peak) correlates with survival in CF, but maximal tests are uncomfortable and resource-intensive. A three-minute step test (STEP) has been validated in CF. Heart rate (HR) recovery after exercise correlates with all-cause mortality in adult non-CF populations. We compared HR recovery after the three-minute step test with VO2 peak in children with CF. METHODS: Twenty-four children with CF performed STEP and a maximal exercise test. Correlation between the tests was assessed. RESULTS: Maximum HR on STEP was lower than on the maximal test (140 vs. 190, p<0.01). Peak HR during STEP correlated inversely with VO2 peak. In subjects with mild lung disease, faster HR recovery after STEP correlated with higher VO2 peak. CONCLUSIONS: The three-minute step test is a feasible submaximal test in this patient population. HR during and after a three-minute step test may reflect VO2 peak in children with CF.
BACKGROUND: Disease progression in cystic fibrosis (CF) is marked by worsening exercise tolerance. Further, maximal exercise capacity (VO2 peak) correlates with survival in CF, but maximal tests are uncomfortable and resource-intensive. A three-minute step test (STEP) has been validated in CF. Heart rate (HR) recovery after exercise correlates with all-cause mortality in adult non-CF populations. We compared HR recovery after the three-minute step test with VO2 peak in children with CF. METHODS: Twenty-four children with CF performed STEP and a maximal exercise test. Correlation between the tests was assessed. RESULTS: Maximum HR on STEP was lower than on the maximal test (140 vs. 190, p<0.01). Peak HR during STEP correlated inversely with VO2 peak. In subjects with mild lung disease, faster HR recovery after STEP correlated with higher VO2 peak. CONCLUSIONS: The three-minute step test is a feasible submaximal test in this patient population. HR during and after a three-minute step test may reflect VO2 peak in children with CF.