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TRAINING TOOL
Heart Rate Zone Calculator
Six Methods. One Tool. Your Numbers.
Enter your age and resting heart rate to calculate your personalised training zones. Six calculation methods including Karvonen, Zoladz, and LTHR — with Zone 2 guidance for Achilles tendinopathy rehab.
THE BASICS
Training Harder Isn't Always Training Smarter
Most people exercise in a grey zone — too hard to recover from properly, too easy to drive meaningful adaptation. Heart rate zones fix that by giving you a precise target for each session based on your own physiology,
not a generic percentage pulled from a chart.
When you know your zones, every session has a purpose. Zone 2 builds aerobic capacity and fat oxidation. Zone 4 pushes lactate threshold. Zone 5 develops peak output. Training without zones is like driving without a speedometer — you might get there, but you won't really know how or why.
For people managing Achilles tendinopathy, zones matter for a different reason: staying active without overloading a reactive tendon requires knowing exactly how hard you're working. Zone 2 is the sweet spot.
THE TOOL
Find Your Zones
Enter your details below. If you're not sure which method to use, leave it on Karvonen — it's the most personalised of the simple options and the one most exercise physiologists recommend.
Zones are estimates based on population formulas. For a personalised assessment, book a consult with Greg.
ZONE 2 & REHAB
Why Zone 2 Is the Rehab Zone
Zone 2 sits at roughly 60–70% of your heart rate reserve. It's the intensity where you can hold a full conversation, breathing is controlled, and you could sustain the effort for an hour without distress. It feels almost too easy. That's the point.
For someone managing Achilles tendinopathy, Zone 2 exercise on a bike, in a pool, or in the water delivers a genuine cardiovascular stimulus without placing meaningful mechanical load on the tendon.
Circulation improves. Cortisol drops. The parasympathetic nervous system — which governs tissue healing and recovery — gets the conditions it needs to function properly.
Tendons exist in a system. The state of that system — stress levels, sleep, nervous system regulation — shapes how well the tendon heals and how it responds to loading. Zone 2 work manages the system, not just the tendon.
Best Zone 2 options during Achilles rehab
→ Stationary or road cycling — minimal ankle load, easy to control intensity
→ Swimming — near-zero Achilles load, excellent cardiovascular stimulus
→ Aqua jogging — maintains running patterns without ground reaction forces
→ Walking on flat ground at a genuinely easy pace
THE METHODS
Which Calculation Method Should You Use?
Each method has different inputs, assumptions, and levels of accuracy.
Here's what separates them — and when each one is appropriate.
Karvonen
← Recommended default
Uses your resting heart rate alongside max HR to calculate Heart Rate Reserve. The most personalised of the simple methods — resting HR reflects your current fitness level, which makes the zones more
accurate to you specifically.
Best for: most people, general rehab, return to sportNeeds: age, resting HR
% of Maximum Heart Rate
The simplest method. Zones are straight percentages of your max HR with no adjustment for fitness level. Quick and widely used but less personalised — two people the same age get identical zones regardless
of fitness.
Best for: beginners, quick reference
Needs: age only
Zoladz Method
Developed by Polish exercise physiologist J.A. Zoladz. Zones are fixed BPM reductions from max HR — simple, requires no resting HR, and gives a target heart rate with a ±5 bpm tolerance rather than a range.
Best for: runners, field-based training
Needs: max HR only
Benson & Connolly
From Heart Rate Training by Roy Benson and Declan Connolly. A percentage of max HR method with refined zone boundaries developed through decades of coaching practice — slightly different thresholds
to the standard % MHR method.
Best for: coached athletes, endurance training
Needs: age only
LTHR — Lactate Threshold
Zones based on your Lactate Threshold Heart Rate — the point where lactate accumulates faster than it clears. The most accurate method for trained athletes. Ideally requires a field or lab test to
determine your true LTHR.
Best for: trained athletes, performance coaching
Needs: tested or estimated LTHR
210 − 0.5×Age (Fixed BPM)
Uses an alternative max HR formula — 210 minus half your age — then subtracts fixed BPM values per zone. A simple field-based method that doesn't require resting HR. Less common but useful as a cross-check
against other methods.
Best for: cross-checking, field use
Needs: age only
Managing Achilles Pain and Ready to Do Something About It?
Zone 2 cardio keeps you moving. But rebuilding a genuinely load-tolerant Achilles tendon requires a structured progressive loading program. The Achilles Load Restoration™ system takes you through 12 weeks of evidence-informed rehab — from isometric loading to pre-elastic readiness.