title: Effects of obstructive sleep apnea and obesity on exercise function in children.
abstract: OBJECTIVE
  Evaluate the relative contributions of weight status and obstructive sleep apnea (OSA) to cardiopulmonary exercise responses in children.
  
  
  METHODS
  Prospective, cross-sectional study. Participants underwent anthropometric measurements, overnight polysomnography, spirometry, cardiopulmonary exercise function testing on a cycle ergometer, and cardiac doppler imaging. OSA was defined as ≥ 1 obstructive apnea or hypopnea per hour of sleep (OAHI). The effect of OSA on exercise function was evaluated after the parameters were corrected for body mass index (BMI) z-scores. Similarly, the effect of obesity on exercise function was examined when the variables were adjusted for OAHI.
  
  
  METHODS
  Tertiary pediatric hospital.
  
  
  METHODS
  Healthy weight and obese children, aged 7-12 y.
  
  
  METHODS
  N/A.
  
  
  RESULTS
  Seventy-one children were studied. In comparison with weight-matched children without OSA, children with OSA had a lower cardiac output, stroke volume index, heart rate, and oxygen consumption (VO2 peak) at peak exercise capacity. After adjusting for BMI z-score, children with OSA had 1.5 L/min (95% confidence interval -2.3 to -0.6 L/min; P = 0.001) lower cardiac output at peak exercise capacity, but minute ventilation and ventilatory responses to exercise were not affected. Obesity was only associated with physical deconditioning. Cardiac dysfunction was associated with the frequency of respiratory-related arousals, the severity of hypoxia, and heart rate during sleep.
  
  
  CONCLUSIONS
  Children with OSA are exercise limited due to a reduced cardiac output and VO2 peak at peak exercise capacity, independent of their weight status. Comorbid OSA can further decrease exercise performance in obese children.
authors.affiliation: The Children's Hospital at Westmead Clinical School, Discipline of Paediatrics & Child Health, Faculty of Medicine, The University of Sydney NSW Australia.
authors.forename: Carla A
authors.initials: CA
authors.lastname: Evans
authors.affiliation: The Children's Hospital at Westmead Clinical School, Discipline of Paediatrics & Child Health, Faculty of Medicine, The University of Sydney NSW Australia ; The Department of Respiratory Medicine, The Children's Hospital at Westmead, Westmead NSW Australia.
authors.forename: Hiran
authors.initials: H
authors.lastname: Selvadurai
authors.affiliation: The Children's Hospital at Westmead Clinical School, Discipline of Paediatrics & Child Health, Faculty of Medicine, The University of Sydney NSW Australia ; Weight Management Service, The Children's Hospital at Westmead, Westmead NSW Australia.
authors.forename: Louise A
authors.initials: LA
authors.lastname: Baur
authors.affiliation: The Children's Hospital at Westmead Clinical School, Discipline of Paediatrics & Child Health, Faculty of Medicine, The University of Sydney NSW Australia ; The Department of Respiratory Medicine, The Children's Hospital at Westmead, Westmead NSW Australia.
authors.forename: Karen A
authors.initials: KA
authors.lastname: Waters
mesh_terms: D015992:Body Mass Index; D001835:Body Weight; D002302:Cardiac Output; D002648:Child; D003430:Cross-Sectional Studies; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D009765:Obesity / Q000150:complications / Q000503:physiopathology*; D017286:Polysomnography; D011446:Prospective Studies; D012890:Sleep / Q000502:physiology; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000503:physiopathology*; D013147:Spirometry
keywords: child; exercise function; heart; obesity; obstructive sleep apnea