title: Influence of Low Peak Respiratory Exchange Ratio on Cardiac Rehabilitation in Patients With Coronary Artery Disease.
abstract: OBJECTIVE
  To compare and analyze the effects of cardiac rehabilitation (CR) in two groups based on the peak respiratory exchange ratio (RERpeak) 1.1 values using the exercise tolerance test (ETT) results, and to investigate the reasons for early termination of ETT.
  
  
  METHODS
  Patients with acute coronary syndrome who participated in CR exercise training were selected and all subjects underwent 6 weeks of CR exercise training. ETT was performed on a treadmill using a Modified Bruce Protocol before and after CR exercise training. According to the result of the first ETT, the subjects were divided into two groups: those with an RERpeak≥1.1 (n=33) and those with an RERpeak<1.1 (n=22). We investigated the reasons for ETT termination and compared the effect of CR between the groups.
  
  
  RESULTS
  The reasons for the early termination of the first ETT in the RERpeak<1.1 group were subjective dyspnea, abnormal cardiovascular responses, leg fatigue and other problems. After a 6-week CR, the peak oxygen consumption (VO2peak) and ETT time increased, and the rate of perceived exertion (RPE) and RPP (rate pressure product) at stage 3 decreased in both the RERpeak<1.1 and RERpeak≥1.1 groups.
  
  
  CONCLUSIONS
  CR exercise training improved exercise capacity, not only in the RERpeak≥1.1 group, but also in the RERpeak<1.1 group. This means that patients with a lower exercise tolerance could also benefit from the effects of CR. Thoughtful consideration to identify the direct and indirect causes for the early termination of ETT would be necessary to improve the efficiency of CR.
authors.affiliation: Department of Rehabilitation Medicine, Inje University Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea.
authors.forename: Chul
authors.identifier: 0000-0001-8223-2945
authors.initials: C
authors.lastname: Kim
authors.affiliation: Department of Rehabilitation Medicine, Inje University Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea.
authors.forename: Hee Eun
authors.identifier: 0000-0002-8753-929X
authors.initials: HE
authors.lastname: Choi
authors.affiliation: Department of Rehabilitation Medicine, Inje University Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea.
authors.forename: Ki Hoon
authors.identifier: 0000-0001-7445-832X
authors.initials: KH
authors.lastname: Lee
authors.affiliation: Department of Rehabilitation Medicine, Inje University Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea.
authors.forename: Young Joo
authors.identifier: 0000-0001-9379-656X
authors.initials: YJ
authors.lastname: Kim
authors.affiliation: Department of Rehabilitation Medicine, Inje University Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea.
authors.forename: Sang Jae
authors.identifier: 0000-0001-9499-3979
authors.initials: SJ
authors.lastname: Lee
keywords: Coronary artery disease; Exercise test; Oxygen consumption; Rehabilitation