Why do two apps show different zones?
They may use different thresholds, percentages or models. Heart-rate reserve zones are not the same as lactate-threshold zones. Compare the definitions before comparing numbers.
How should I choose running paces?
Start with a recent representative race and use a range. Easy pace needs room for fatigue, terrain and conditions. A model should support the session, not dominate it.
Is 95% of a 20-minute test my FTP?
It is a common estimate. Anaerobic contribution and fatigue vary between athletes, so training response and repeated testing should check the value.
Can a zone tell me when to recover?
A zone describes intensity. It cannot see your entire week, sleep or developing fatigue. Use the numbers alongside feedback.
Where does this guidance come from?
Primary source and methodology. Use the calculator’s method notes for assumptions. Coaching decisions still require your context.
Use the related calculator