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Relationship between training heart rate and aerobic threshold in exercising cardiac patients

University of British Columbia

The purpose of this study was to examine the relationship between training heart rate (THR) and the HR occurring at the Aerobic Threshold (AerTHR), and to examine the AerT as an index of training intensity in selected coronary artery disease (CAD), post-myocardial infarction (MI), and post-coronary artery bypass surgery (CABS) patients. Twenty male subjects (age=54.9; wt=73.7 kg; %body fat=25.8) were recruited on the basis of regular participation in a cardiac rehabilitation program (CRP) (3/week at 70 - 85% HRmax) for 6 months; no beta-adrenergic medication; and symptom-free during exercise. Field measurements of THR during the aerobic phase at CRP was carried out by computer-assisted portable telemetry with mean THR computed from each 30 minute value per subject. A maximal treadmill test starting at 2.5 mph at 0% grade with speed increasing 0.5 mph each minute was carried out using a Beckman MMC for 30 second determinations of respiratory gas values. The AerT was determined by visual inspection of the first departure from linearity of Ve and excess CO₂. VO₂max was 35.6 ±5.6 ml/kg/min⁻¹, with HRmax 166.2 ±11.8 bpm. Paired t-tests were performed; AerTHR was 124.8 ±15.3 bpm with THR 133.7 ±13.4 bpm (p < .03). Percent HRmaxAerT was 75.1 ±8.05 and %HRmaxTHR was 80.6 ±8.3 (p < .03). Mean %VO₂maxAerT (54.4 ±6.7) is consistent with other reported data showing .lower values in less trained individuals. Stepwise correlations were performed, and a regression equation was produced to predict AerT grom HRmax, height, and weight with a multiple r = .74 (p < .01). These data suggest that in this population, THR, as calculated by the relative percentage of maximum method, produces training intensities above the AerT expressed as absolute or relative percents of HRmax. This finding may have implications for optimal body fat reductions, patient compliance to the exercise program, and safety in CRP's.

Text

2010-03-31

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http://hdl.handle.net/2429/23236

Physical Education

University of British Columbia

Graduate