Calories burned
FeedbackSee Calories Burned After Every Session
The session summary now shows an estimated calorie burn for every workout, along with two facts to put it in context: how much extra your metabolism burns in the hours afterward (the “afterburn” effect), and how many sessions like this one add up to 1 kg of fat loss.
The Afterburn Effect (EPOC)
Intense cardio keeps your metabolism raised for a while after you stop. This is called EPOC. Excess Post-exercise Oxygen Consumption. EPOC isn’t a fixed percentage of calories burned. It scales non-linearly with intensity. Research (Bahr & Sejersted, 1991; LaForgia et al., 2006) finds it rises exponentially with effort but never exceeds about 15% of the extra calories the workout cost. How afterburn is estimated has the formula.
ZonePoints uses the time you spent in each zone (already tracked for your zone points score) to calculate a weighted afterburn that shows exactly how hard each part of the session was. A session spent mostly in Zone 4 and 5 shows a proportionally larger afterburn than the same total calories at Zone 1 and 2.
Fat-Loss Context
One kilogram of body fat stores about 7,700 kcal. ZonePoints shows how many sessions at your current intensity (workout plus afterburn) add up to that milestone. That gives you a clear target to aim for.
Personalise Your Estimate
By default the app assumes a weight of 70 kg. For a more accurate number, open Settings → Calorie estimation and enter your weight and sex. Weight scales calorie output directly. Sex adjusts the aerobic capacity coefficient to reflect documented differences at the same training status. Everything you enter stays on your device.
How It Works
The app builds the estimate directly from your zone points (no extra data needed. Zone points accumulate as speed × minutes, where speed encodes your heart-rate reserve (%HRR) at each moment. So total zone points are mathematically equal to the sum of %HRR × minutes across your session) exactly the workload integral exercise physiologists use to measure cardiovascular effort. Dividing by training time gives your average %HRR in one step.
Next, the app uses the standard Karvonen VO₂ model, established by Swain et al. (1994, 1997), who showed that %HRR and %VO₂max are essentially interchangeable:
VO₂ = VO₂rest + %HRR × (VO₂max − VO₂rest)
The app estimates VO₂max from your stored max and resting heart rates using the Uth–Sørensen–Overgaard–Pedersen formula (2004): VO₂max ≈ 15.3 × HRmax / HRrest. Fitter people have a lower resting rate compared to their max so they get a higher VO₂max. One litre of O₂ releases roughly 5 kcal. That gives calories per minute, which the app multiplies by training time.