Training Zone Check-IN

Effective training zones correspond with specific energy systems. If training zones are off, an athlete could train one system too much and another not enough, leading to under-achieving or over-training.


Here is an example of a Training Zone system an athlete might use:


Zone 1 – Easy / Recovery

Zone 2 – Endurance

Zone 3 – Tempo

Zone 4 – Sub-Threshold / Threshold

Zone 5 – Above Threshold / VO2 max

Zone 6 – Anaerobic / Sprint


Here is an overview of energy systems involved in a purposefully designed training zones system:

Lipolysis: the metabolism of fat.                                                        (Zone 1, 2)

Aerobic Glycolysis: aerobic metabolism of carbohydrates.        (Zone 1,2, 3, 4)

Lactate Acid Cycle: reconverts lactate into glycogen                    (Zone 1,2,3,4,5,6)

Anaerobic Glycolysis: anaerobic metabolism of carbohydrates    (Zone 5,6)

Stored ATP access: quick anaerobic bursts of energy for sprints   (Zone 6)

Creatine Phosphate Shuttle:  reconverts ADP into ATP.              (Zone 6)


Our fitness changes from year to year and throughout the season. How significantly training zones change will depend largely on how you train and your training history. An injury, sickness, length of break, years of experience, etc. can also affect this.  The heart rate zones will often stay the same, but the watts or pace may vary considerably (ideally go up 😀).  For instance, if you used the same Functional Threshold Power for workouts in July as in March, you might be undercutting your potential. In contrast, if riding at the heart rate correlated with your Functional Threshold Power from March in July, you would most likely be riding at watts higher than the FTP-modeled workouts from March.  In this case, lactate stays lower, and fat oxidation remains high at higher workloads, which is good!


Heart Rate zones can also change.  Typically, we see more significant changes in Heart Rate zones in athletes with less endurance training experience or returning from time off.  Heart Rate changes can result from increased stroke volume, where the athlete pumps more blood with every beat.  Additionally, heart rate zones can shift as plasma volume shifts throughout a season. 


Assessing your training zones through a metabolic test once or twice a year can help you get the most out of your workouts. Three or four weeks into the base-building period, following a peak, taper, and rest, is an ideal time to re-assess your physiology. Assessing at this time ensures you are training the intended physiological systems as you build into larger training volumes.