Most training plans are based on Intensity. Intensity is described by five training zones, Zone 1 to Zone 5. Many triathlon training plans divide the top zone in three: Zone 5a, 5b, and 5c. Athletes can use these zones to "tune" each workout for the best results.
The zones are set based on percentages of generally one of three values:- Lactate Threshold
- VO2 Max
- Maximum Heart Rate
Of these, Lactate Threshold has been shown to be one of the best predictors of endurance performance. Lactate threshold is the point at which your body can no longer get rid of the lactic acid produced by your muscles, and it starts to accumulate in the blood. This lactate threshold is closely correlated with heart rate and breathing rate.
VO2 Max represents the maximum amount of oxygen that can be used by the muscles during a specified period. Your base VO2 Max is genetically determined, but you can increase it by training. Maximum heart rate is, well, maximum heart rate.
Measuring lactate threshold require a medical test while on a treadmill or stationary bike. It can also be estimated based on very specific "field tests" on the bike or run. However, since there is the correlation to heart rate, which is easier to estimate, we most often talk about heart rate zones.
You can see how to estimate your Maximum Heart Rate and heart rate training zones here. An alternative is the Borg Rate of Perceived Exertion, which is explained here.
Note: Heart Rate Zone values are based on running. For each zone, subtract 10 beats per minute for biking and 10-15 beats per minute for swimming.
- Zone 1: Recovery
- Also known as: Overdistance
Intensity: Very Low
% Lactate Threshold: 65%-84%
% VO2 Max: 55%-65%
% Max Heart Rate: 60%-70%
RPE Scale: 6-9
Used for: These are the easiest workouts, used to promote recovery after harder workouts. It is also generally the intensity level used during the recovery period of interval work and long slow distance (LSD) runs. - Zone 2: Endurance
- Also known as: Extensive Endurance
Intensity: Moderate
% Lactate Threshold: 85%-91%
% VO2 Max: 66%-75%
% Max Heart Rate: 71%-75%
RPE Scale: 10-12
Used for: Used for long, endurance workouts and easy speed workout; builds and maintains aerobic endurance. - Zone 3: Lactate Threshold
- Also known as: Intensive Endurance
Intensity: Moderate Plus
% Lactate Threshold: 92%-95%
% VO2 Max: 76%-80%
% Max Heart Rate: 76%-80%
RPE Scale: 13-14
Used for: Used for Tempo workouts, training in Zone 3 is usually done in the preparation and base phases. Generally, in the later phases you want to bump up to Zone 4. - Zone 4: VO2 Max Intervals
- Also known as: Anaerobic Threshold, Race/Pace
Intensity: Race/Pace
% Lactate Threshold: 96%-100%
% VO2 Max: 81%-90%
% Max Heart Rate: 81%-90%
RPE Scale: 15-16
Used for: Intervals, hill work, and tempo work. Intervals in this zone generally have work-to-rest ratio of 3:1 or 4:1. Training at or slightly below your Lactate Threshold (a.k.a. Anaerobic Threshold) helps your body lean to "recycle" the lactic acid during high intensity work. - Zone 5a: Threshold Endurance
- Also known as: Superthreshold
% Lactate Threshold: 100%-102%
% VO2 Max: 91%-93%
% Max Heart Rate: 91%-93%
RPE Scale: 17
Used for: Intervals, hill work, and tempo work; typically used after some Zone 4 time has already been done. Zone 5 workouts are very short because it is difficult to maintain this level for any length of time. - Zone 5b: Anaerobic Endurance
- Also known as: Speed Endurance
% Lactate Threshold: 103%-105%
% VO2 Max: 94%-98%
% Max Heart Rate: 94%-98%
RPE Scale: 18-19
Used for: Intervals and hill work to improve anaerobic endurance. Intervals in this zone generally have work-to-rest ratio of 1:1, for example, a 20 second sprint followed by 20 seconds of easy recovery (Zone 1). - Zone 5c: Anaerobic Capacity
- Also known as: Power
% Lactate Threshold: 106%+
% VO2 Max: 98%-100%
% Max Heart Rate: 98%-100%
RPE Scale: 20
Used for: Short-term Sprinting. Intervals in this zone have a work to rest ratio of 1:2 or more.
For More Information, See:
Training Plans for Multisport Athletes, by Gale Bernhardt
Serious Training for Endurance Athletes, by Rob Sleamaker and Ray Browning
The Triathlete's Training Bible, by Joe Friel