title: How does heart rate recovery after sub-maximal exercise correlate with maximal exercise testing in children with CF?
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.
authors.affiliation: University of Pittsburgh School of Medicine, 5806 Ellsworth Ave #1, Pittsburgh, PA 15232, United States.
authors.forename: Sarah P
authors.initials: SP
authors.lastname: Cohen
authors.affiliation: Department of Pediatrics, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC, United States. Electronic address: davido@pitt.edu.
authors.forename: David M
authors.initials: DM
authors.lastname: Orenstein
mesh_terms: D000293:Adolescent; D002648:Child; D015331:Cohort Studies; D003550:Cystic Fibrosis / Q000503:physiopathology*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005240:Feasibility Studies; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D011237:Predictive Value of Tests; D020127:Recovery of Function / Q000502:physiology; D013997:Time Factors; D055815:Young Adult
keywords: Cystic fibrosis; Exercise testing; VO2max; heart rate recovery