What is Heart Rate Reserve (HRR)?

Heart Rate Reserve is the difference between your maximum heart rate and your resting heart rate. It represents your body's usable dynamic range for physical exertion.

Updated: August 2026 • Verified v1.2

Heart Rate Reserve (Karvonen) Exercise Training Zones Calculator

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HRR = MaxHR - RestingHR; TargetHR = (HRR * Intensity%) + RestingHR

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Understanding Your Results

Calculates estimated Max HR (Tanaka clinical formula: $208 - 0.7 \times \text{age}$), Heart Rate Reserve ($HRR = MaxHR - RHR$), and exact BPM thresholds for Zones 1 through 5 with physiological benefits.

Practical Guidance & Next Steps

Zone 2 (60% - 70% HRR) is the optimal training zone for mitochondrial density, capillary growth, and metabolic efficiency without accumulating systemic fatigue.

What is this?

A cardiovascular health utility that calculates personalized exercise heart rate training zones based on resting and maximum heart rates.

How does it work?

1. Enter age and resting heart rate (bpm). 2. Optionally enter a tested custom Max HR or use the Tanaka clinical formula. 3. View Heart Rate Reserve (HRR) and exact BPM boundaries for Zones 1 through 5.

Why use it?

Delivers personalized training zones far more accurate than crude standard formulas.

Technical Scope & Calculation Limitations

Calculates clinical Karvonen and Tanaka exercise physiology formulas.

Frequently Asked Questions

The standard `220 - age` formula completely ignores resting fitness. A fit athlete with a resting heart rate of 45 bpm has a vastly different cardiovascular reserve than a sedentary person with a resting heart rate of 80 bpm, even if they are the exact same age. Karvonen accounts for this individual baseline.

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