Target Heart Rate Calculator

The target heart rate calculator uses the Karvonen formula to prescribe safe exercise intensities. Essential for cardiac rehabilitation, fitness programs, and sports physiotherapy.

Clinical Applications

• Exercise prescription in cardiac rehabilitation programmes — ensuring safe training intensity within prescribed HR zones
• Progressive loading in post-MI, heart failure, and post-CABG physiotherapy
• Sports physiotherapy — optimising training zones for endurance athletes using heart rate reserve
• Pulmonary rehabilitation — titrating aerobic exercise intensity for COPD and ILD patients

How to Interpret Results

• The Karvonen formula accounts for resting heart rate (heart rate reserve), making it more individualised than simple percentage-of-HRmax methods
• Always verify resting heart rate in a true resting state (supine, 5 minutes quiet rest) — errors here propagate through the entire calculation
• Beta-blockers and other chronotropic medications attenuate HRmax and HRreserve — in medicated patients, use Borg RPE scale as a parallel measure

1. 1.Karvonen MJ, Kentala E, Mustala O (1957). The effects of training on heart rate: a longitudinal study. Annales Medicinae Experimentalis et Biologiae Fenniae, 35(3), 307–315.
2. 2.American College of Sports Medicine (2013). ACSM's Guidelines for Exercise Testing and Prescription, 9th ed. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins.
3. 3.Swain DP, Leutholtz BC (1997). Heart rate reserve is equivalent to %VO2 reserve, not to %VO2max. Medicine & Science in Sports & Exercise, 29(3), 410–414.