Personalized determination of target training heart rates for all ages, including patients with heart disease
Authors: Traninger Heimo , Haidinger Manuela , Zemljic-Harpf Alice H. , Harpf Hanns H. 
Published: April 2020

Background

Lack of physical exercise was recently accepted as a clinical diagnosis (ICD‐10‐CM Z72.3). The prescription of exercise requires a personalized training plan. Currently the Karvonen formula is used to calculate a target training heart rate (HR) by subtracting the age from 220. Because of individual differences in aerobic exercise capacities, resting parasympathetic tone, cardiac disease state, co‐morbidities, and medications (especially beta blocker), we suggest applying treadmill exercise tolerance testing to determine a personalized training HR zone, including patients with heart disease.

Methods and study protocol

In 1999, the Austrian ambulatory cardiac rehabilitation was established and currently includes 12 centers. The cardiac rehabilitation program consists of three phases; phase I begins during the hospital stay, while phase II (6 weeks, 4 times/week) and phase III (up to 13 months, 2 times/week) are conducted in ambulatory cardiac rehabilitation centers under physician supervision. Additional home‐based training is recommended every day of the week. Male and female subjects participating in phase II and phase III rehabilitation underwent initial screening, and subjects with aortic stenosis, low systolic output (EF% < 15), and dyspnea at rest (NYHA Class IV) were excluded. Bicycle ergometer exercise protocols used were 10W/10W/min (~90% of subjects) or 20W/20W/min (~10% of subjects) and HR was monitored continuously to generate a continuous HR curve to show a clear HR deflection point.

Results

We retrospectively analyzed 9042 ECG treadmill test results (male = 7053, female = 1989) conducted at the Center for Ambulatory Rehabilitation Graz between 1‐1‐1999 and 10‐31‐2019. No significant difference in maximal training capacities was found between male and female subjects. Under physician supervision treadmill exercise tolerance testing was safe and well tolerated by maximally challenged male and female subjects of all ages, and no cardiac or cerebral events occurred during or after treadmill testing. The HR deflection point was assessed for each subject. The personalized training HR zone was compiled of 80–95% of the HR deflection point (not 220‐age), and training initiated during phase II and continued during phase III. Subjects were encouraged to achieve optimal training HR for 30 minutes daily and advised to perform muscle strengthening exercises twice per week.

Conclusion

Our study shows that optimal training heart rates can be determined by treadmill exercise testing, when patients are maximally challenged. Once “true” exhaustion is tested (which is often not achieved) a personalized target training HR zone can be calculated utilizing the individual HR deflection point. This approach will offer two advantages: 1) evaluation of underlying cardiovascular disease (cardiac ischemia), and 2) determination of an individualized and recommended target training heart rates for the “medical prescription of exercise”.