title: Comparison of cardiorespiratory responses during aquatic and land treadmill exercise in patients with coronary artery disease.
abstract: OBJECTIVE
  To investigate cardiorespiratory responses during exercise stress tests using an aquatic treadmill and a land-based treadmill in patients with coronary artery disease (CAD).
  
  
  METHODS
  Twenty-one stable CAD patients were enrolled. All patients participated in 2 symptom-limited incremental exercise tests, using both an aquatic and a land treadmill. For the aquatic treadmill protocol, patients were submerged to the upper waist in 28°C water. The treadmill speed started at 2.0 km/h and increased 0.5 km/h every minute thereafter. For the land treadmill protocol, the speed and gradient were started at 2.4 km/h and 1.5%, respectively. The speed was increased by 0.3 km/h and grade by 1% every minute thereafter. Oxygen consumption ((Equation is included in full-text article.)O2), heart rate (HR), and respiratory exchange ratio were measured continuously and peak values recorded. Rating of perceived exertion, percentage of age-predicted maximal HR, and total exercise duration were also recorded.
  
  
  RESULTS
  Peak cardiorespiratory responses during both protocols were compared. The peak (Equation is included in full-text article.)O2 and peak HR did not show any significant differences. The peak respiratory exchange ratio was significantly greater using the land treadmill than the aquatic treadmill protocol. Rating of perceived exertion, age-predicted maximal HR percentage, and total exercise duration were similar for both protocols. There was a significant linear relationship between HR and (Equation is included in full-text article.)O2 with both protocols.
  
  
  CONCLUSIONS
  This study demonstrated that aquatic treadmill exercise elicits similar peak cardiorespiratory responses compared with land treadmill exercise, suggesting that aquatic treadmill exercise may be effective for CAD patients in cardiac rehabilitation.
authors.affiliation: Department of Rehabilitation Medicine (Drs Choi, Kim, Han, Kim, and Lee, and Mr Yoon) and Division of Cardiology, Department of Internal Medicine (Drs Joo and Kim), Jeju National University Hospital, University of Jeju School of Medicine, Jeju, Republic of Korea.
authors.forename: Jun Hwan
authors.initials: JH
authors.lastname: Choi
authors.forename: Bo Ryun
authors.initials: BR
authors.lastname: Kim
authors.forename: Seung Jae
authors.initials: SJ
authors.lastname: Joo
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Han
authors.forename: Song Yi
authors.initials: SY
authors.lastname: Kim
authors.forename: Sun Mi
authors.initials: SM
authors.lastname: Kim
authors.forename: So Young
authors.initials: SY
authors.lastname: Lee
authors.forename: Ho Min
authors.initials: HM
authors.lastname: Yoon
mesh_terms: D000368:Aged; D003324:Coronary Artery Disease / Q000503:physiopathology / Q000534:rehabilitation*; D004734:Energy Metabolism; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006875:Hydrotherapy; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D012123:Pulmonary Ventilation / Q000502:physiology