A training zone is a range of exertion that defines the upper and lower limits of training intensities. It determines a set intensity for athletes to work at during an activity. Zones are defined by pulse, power (in watts), or even pace. Whether you are training according to speed, heart rate or power, your training zones are individual and constantly change according to your fitness level. 2PEAK training plans use the standard system of 5 training zones. Each training session is displayed according to these zones. 2PEAK Performance test: MAS Test Blog article: Automatic Running Training Zones