What is the training zone for improving anaerobic fitness?

What do your training zones mean in terms of intensity levels and the types of training effects you are trying to achieve? Read this guide to find out–excerpted from The Triathlete’s Training Guide.

Your training zones are the target ranges (of heart rate, pace or perceived exertion) that will be used to prescribe workout intensities. It is important to recognize that there are different nomenclatures used to talk about training zones. Some systems use fewer zones (as few as four) and some more (up to eight). Each zone corresponds to a different intensity level.

Figure 3-1 depicts a common system that uses seven zones. The first four zones correspond to aerobic intensity levels. The last three zones fall within the anaerobic range. The lactate threshold falls right at the bottom of Zone 5a, acting as the boundary between aerobic and anaerobic intensity.

Of the four aerobic zones, Zone 1 is used primarily for recovery and warmup or warmdown efforts. Zone 2 is the primary aerobic base building zone. This is the zone for long slow distance (LSD).

Zone 3 represents a more challenging aerobic pace. It’s still well within the aerobic range but involves a peppier tempo that can be hard for the uninitiated or untrained. Think of this as aerobic tempo pace. Working in this zone is a stepping stone to tempo work that is closer to lactate threshold. But the intensity of this zone is typically too slow to gain much benefit for raising the lactate threshold and too fast to achieve the aerobic benefits of Zone 2 without causing undue wear and fatigue. Since there is little direct benefit to working in this zone, it is used sparingly and mostly avoided.

Zone 4 moves toward the lactate threshold but remains sub-threshold. This is the “comfortably hard” effort that runners refer to when talking about tempo runs.

The lactate threshold arrives at the bottom of Zone 5a, so Zone 5a corresponds to the super-threshold range. The sub- and super-threshold zones represent an important range that targets increases in the lactate threshold. Tempo workouts and cruise intervals in Zone 4 or Zones 4-5a improve lactate tolerance and decrease lactate accumulation, which enhances the ability to sustain race pace.

Zone 5b is the next step in the anaerobic range. This range corresponds to the athlete’s maximal oxygen consumption, or VO2max. Working in this zone expands aerobic capacity.

Finally, Zone 5c emphasizes anaerobic capacity. Work in this zone targets the ability to work anaerobically for events or portions of events that last a few minutes in length—such as starts, race surges, and finishing kicks.

Remember, the nomenclature used here is but one way to talk about intensity levels. It is particularly useful if you use the Training Peaks online training log to track and analyze your training. Triathlon and cycling coach Joe Friel, one of the founders of Training Peaks, uses the system; and many tools provided on Training Peaks make it easy to plug in your individual heart rate and pace data to calculate your zones according to this system.

Description and uses of training zones

Learn more in The Triathlete’s Training Guide

Zone 1 (Recovery)
Easy effort. Used for warmups and warmdowns, recovery workouts, and easy workouts that add to aerobic base.

Zone 2 (Aerobic Base / Extensive Endurance)
Used more than any other training zone to build the aerobic base, which allows the athlete to better metabolize fat and spare glycogen (stored carbohydrate) as a long duration energy source. Typical workouts involve continuous efforts with durations of 20 minutes up to several hours.

Zone 3 (Aerobic Tempo / Intensive Endurance)
Used to build intensive aerobic endurance and improve lactate tolerance. Typical workouts involve sustained tempo for up to an hour or long intervals (e.g. 5-20 min) with a 5:1 work to recovery ratio.

Zone 4 (Sub-Lactate Threshold, or LT)
Used to raise the lactate threshold by improving lactate tolerance and decreasing lactate accumulation, which allows the athlete to stay aerobic at faster speeds. Typical workouts involves sustained tempo for up to an hour or long intervals (e.g. 5-20 min) with a 5:1 work to recovery ratio.

Zone 5a (Super-Lactate Threshold, or LT)
Used to raise the lactate threshold by improving lactate tolerance and decreasing lactate accumulation, which allows the athlete to stay aerobic at faster speeds. Typical workouts involves sustained tempo for up to an hour or long intervals (e.g. 5-20 min) with a 5:1 work to recovery ratio.

Zone 5b (Aerobic Capacity, or VO2max)
Used to increase the maximal rate of oxygen transport (aerobic capacity or VO2max), build lactate tolerance, and increase anaerobic endurance. Typical workouts involve work intervals of 3-7 minutes in duration with recovery interval equal to or slightly less than work interval.

Zone 5c (Anaerobic Capacity)
Used to improve the ability to maintain short durations of speed of up to 2 minutes in duration (starts, race surges, finishing kicks). Typical workouts involve work intervals up to 2 minutes in duration with recovery interval equal to or greater than work interval to allow full recovery.