Stöggl & Sperlich 2015, Training-intensity distribution and the three-zone model

Review of intensity distribution in endurance athletes using the three-zone model, anchored to the two thresholds: Zone 1 below the first threshold, Zone 2 between the thresholds, Zone 3 above the second. This is a different construction from a five-zone percentage-of-maximum-heart-rate scheme or a seven-zone power scheme, which is why the same “zone number” denotes different intensities across systems. Well-trained athletes concentrate most work in Zone 1. Strong (for the model definitions).