Does the ventilatory anaerobic threshold precede the ischemic threshold in cardiac patients undergoing exercise testing?
Exercising at the ventilatory anaerobic threshold precedes the ischemic threshold in the vast majority of patients, suggesting it is a safe and suitable target heart rate for cardiac rehabilitation.
BACKGROUND: Exercise prescription for patients with cardiovascular disease remains a challenge. The concept of exercising at an intensity equivalent to one's anaerobic threshold has been well studied and highly recommended in the fitness industry for other populations. For this concept to be applicable to patients with cardiovascular disease, the level and intensity of activity must not trigger myocardial ischemia. HYPOTHESIS: in a majority >50% of patients). METHODS: In this retrospective pilot study, 19 patients, mean age at baseline of 45.0 ± 15.6 years, who had positive cardiopulmonary exercise stress testing were included. Heart rate at ventilatory anaerobic threshold (VAT) was derived from a computer-analyzed V-slope method. The ischemic threshold (IT) was determined from electrocardiogram. The exercise test parameters at VAT in relation to IT were examined. RESULTS: Heart rate at VAT preceded heart rate at IT in 89.5% of patients. On average, achievement of VAT preceded IT relative to workload (119.5 ± 49.6 vs 132.6 ± 47.5; P < 0.01), heart rate (121.2 ± 15.9 vs 133.3 ± 17.5; P < 0.01), oxygen consumption (19.3 ± 4.9 vs 20.8 ± 3.7; P < 0.01), and respiratory exchange ratio (0.96 ± 0.10 vs 1.01 ± 0.07; P < 0.01). CONCLUSIONS: ; therefore, we propose that anaerobic threshold is a suitable target aerobic exercise heart rate for all patients with cardiovascular diseases indicated for cardiopulmonary rehabilitation.
Tan et al. (Thu,) studied this question.