Heart Rate at the Estimated Lactate Threshold in Patients With Chronic Obstructive Pulmonary Disease: Effects on the Target Intensity for Dynamic Exercise Training

BACKGROUND: Physical training at the range of exercise intensities associated with sustained blood lactate accumulation seems to rapidly improve aerobic performance in both healthy subjects and patients with chronic obstructive pulmonary disease (COPD). However, it is still unclear whether patients' heart rate (HR) at the estimated lactate threshold (HR [symbol: see text]L)--as expressed in percent attained peak HR (AHR), predicted peak HR (PHR) and HR reserve (HRR)--are comparable with the ranges of intensity that are commonly used for target exercise training in control subjects. METHODS: The authors evaluated 26 patients with stable COPD (forced expiratory volume in 1 second = 1.17 +/- 0.28 L) who were submitted for spirometric evaluation, and, after familiarization, to a symptom-limited ramp-incremental cardiopulmonary exercise testing on a cycle ergometer. RESULTS: The authors were able to identify [symbol: see text]L in only 18 patients (69%). The HR [symbol: see text]L corresponded to wide range of exercise intensities according to the three methods (ranging from 70-95% AHR, 50-90% PHR, and 35-60% HRR). However, most of the subjects would be trained within +/- 5% HR [symbol: see text]L if they had been exercised at 80 to 85% AHR and 40 to 45% HRR; these values correspond to higher (AHR) and lower (HRR) intensities than usually recommended for healthy subjects. CONCLUSIONS: Considering that [symbol: see text]L was not identified in approximately one third of the patients and there was ample variability on HR [symbol: see text]L as %AHR, %PHR, and %HRR, the use of HR and [symbol: see text]L targets for routine exercise prescription does not seem to be clinically justifiable in patients with COPD submitted to pulmonary rehabilitation.