Tempo Zone 3

Zone 3 is the first zone that should be used for training sessions involving specific efforts. 

Often referred to as the “grey zone”, the intensity of exercise performed in this zone can be described as hard but not too hard, just enough to give you that feeling of having done work as well as an impressive average pace to show on Strava. 

It corresponds to the intensity at which a marathon (for faster runners <4hrs) or half marathon (for slower runners >2hrs) is run. 

The aim of training in zone 3 is to develop an athlete’s aerobic capacity at higher power outputs than those reached in zones 1-2. However, the added fatigue associated with training at this higher intensity means that its use should be restricted to prevent injury development or overtraining.

My advice is to be careful with Zone 3, making sure to use it only for targeted efforts.