Do Clinical Exercise Tests Permit Exercise Threshold Identification in Patients Referred to Cardiac Rehabilitation?

Randi R. Keltz, The University of Western Ontario

Abstract

The purpose of this thesis was to quantify the proportion of patients whose clinical cardiopulmonary exercise test (CPET) permitted identification of estimated lactate threshold (θ_LT) and respiratory compensation point (RCP) and to characterize the variability at which these thresholds occur to evaluate the feasibility of “threshold-based” aerobic exercise prescription. We retrospectively analyzed CPET data of 1102 patients (65±12 yrs; 306 females) referred to cardiac rehabilitation. θ_LT and RCP were identified and reported as oxygen uptake (V̇O₂), heart rate (HR), %V̇O_2peak, and %HR_peak. Patients were grouped by threshold identification: group 0) neither θ_LT nor RCP (n=556; 50%); 1) θ_LT only (n=196; 18%); 2) both θ_LT and RCP (n=350; 32%). Compared to group 1, θ_LT in group 2 occurred at a higher V̇O₂ and HR, but lower %V̇O_2peak and %HR_peak (p