Training Zone Overview

Training Zones are the various levels at which athletes train in order to acheive specific results. Every training program, regardless of level / sport / athlete, must include a variety of training stimuli to achieve improved fitness. Doing 20 sit ups is helpful, but after you have mastered this, you mus move on to new challenges if you seek to improve. Always doing 20 sit ups will only get you so far.


Recovery days or between intervals. A very easy, aerobic effort.

Basic Endurance

Long endurance training and base building. Spending time in Zone 2 enables athletes to build durability, boost aerobic fitness and develop the proper technique. Also referred to as "Steady".
The infamous gray area…it’s either either too hard or too easy and should be avoided in favor of Z2 or Z4+ workout. At the end of longer workouts, athletes may drift into this area. Also referred to as "Moderate".
Z4 is just below threshold. Training at this level is extremely beneficial as it avoids lactate build-up. Results in improved lactate buffering and economy. Also referred to as "Mod Hard".
Same as above, only intervals are shorter due to lactate accumulation.
Anaerobic Endurance
Improved lactate tolerance and economy. Useful for Sprint and Olympic training, less so for endurance athletes. Also referred to as "Hard".
Very short, max effort burst. Not very useful for endurance training. Recruits "fast-twitch" muscle fibers.

Zone 1 – Recovery: This is the zone most commonly used during recovery between intervals, or on easy "recovery" days. Intensity is well below LTHR, and you are focusing on improving technique and staying loose.

Zone 2 – Basic Endurance: Most long endurance training sessions are done within Zone 2, aka at a "conversational effort." Exercise in Zone 2 is measured in hours. Valuable time can be spent here by athletes of all abilities.

Zone 3 – Tempo: With the exception of early base training, if you find yourself in Zone 3, its is more efficient either move down Zone 2 or up to Zone 4+.

Zone 4 – Sub-Threshold: In this zone, your body is at its maximally aerobic state. This is the fastest you can go and not be anaerobic. Because you are still aerobic (technically), you can maintain this pace for several minutes, allowing your body to learn how to deal with onset of lactate without the hassle of having to process it. Be cautious here. Requires 50% to as little as 25% of the work interval for recover.

Zone 5a – Super-Threshold: In this zone, your body is anaerobic. This IS redlining it. Great for boosting lactate tolerance, but hard on the body. Requires 100% to 150% of the work interval for recovery.

Zone 5b – Anaerobic Endurance: Training in this zone increases the body’s tolerance of high levels of lactate. Because you can only maintain this effort for a short period, intervals are the most common Zone 5b workout. During interval training, intensity is maintained for a few minutes in Zone 5b, triggering an adaptive response. We then rest, allow the body time to flush out the lactate, and then repeat the exposure. Requires 100% to 200% of the work interval for recovery.

Zone 5c – Power: These are extremely short, maximum effort bursts of intensity. Their value to the multisport athlete is limited, with the exception of those severely lacking in force and power. Usually done in sets of close succession w/ a long rest interval between each set: so 3 x 20 seconds of Z5c effort with 40 seconds of rest after each and 10 minutes of rest until the next set.

(Source: "Triathlete’s Training Bible," by Joe Friel.)