Exercise Prescription Cardiac Safety Index (HR Zones + Meds) Calculator

Exercise Prescription Cardiac Safety Index (HR Zones + Meds): Explanation and Clinical Context This calculator provides individualized heart rate training zones integrating medication effects and cardiac safety factors. It uses the heart rate reserve (HRR) formula when resting HR is available and adjusts predicted HRmax for patients on beta-blockers using the Brawner equation (HRmax ≈ 164 − 0.7×age), otherwise the Tanaka formula (HRmax ≈ 208 − 0.7×age). Training zones follow ACSM guidelines: light (30–39% HRR), moderate (40–59% HRR), vigorous (60–89% HRR).

For patients on rate-limiting medications or with non-sinus rhythm, intensity should be guided by perceived exertion (RPE) and clinical judgment. When ischemic threshold is known, HR targets should remain at least 10 bpm below that value.