Every workout needs to be done with a specific purpose in mind, and planned. Training, whether done on your own or following a coaching plan, typically has three dimensions: frequency, duration and intensity. Frequency is how often, and duration how long — distance, e.g., a 1,000-meter swim in the pool, or time, e.g., a one-hour run. Intensity is harder to quantify, but basically means how hard.

If you’ve looked at multisport training plans from a coach or online, you’ll often see intensity specified in terms of training zones. Different coaches may use a different number of training zones, but traditionally in triathlon training we’ve had five zones, known as Zone 1, Zone 2, Zone 3, Zone 4 and Zone 5. For more advanced endurance athletes, Zone 5 is sometimes subdivided into three zones: Zone 5a, 5b and 5c.

Training in a specific zone leads to specific adaptations. Zone 1 is the lowest intensity, used for warm-up, cooldown and recovery workouts. Zone 5 is the highest intensity. Zones 1 through 4 are aerobic, Zone 5 (and its subdivisions) are anaerobic. Simplifying things quite a bit, Zone 2 trains for endurance, Zone 3 trains for endurance during early season training, and Zone 4 trains the body to better tolerate and remove lactic acid (the waste product produced by muscles during exercise). Zone 5 trains for speed and power, and to work longer in an anaerobic state.

So how to you know what your training zones are? One of the easiest to use is the Rate of Perceived Exertion, also known as the Borg scale. Here intensity is estimated based on your breathing rate; the harder you breathe, the more intense you’re exercising. In Zone 2, for example, you’re breathing harder but can still carry on a conversation with your workout partner. In Zone 4 it’s uncomfortable to talk, and in Zone 5 you don’t want to talk!

Borg Rate of Perceived Exertion

Breathing rate is somewhat subjective, and triathletes like nothing better than objective numbers, so training zones are often calculated as a range of heart rates. And that calculation depends on a value that isn’t that easy to determine exactly — the maximum heart rate or HRmax. You can get a good idea of maximum heart rate by going to a lab and getting tested (which is expensive and typically involves being wired up, having a hose stuck in your mouth and your nose pinched and running on a treadmill until you can’t run any longer). Luckily, there are several ways to estimate your maximum heart rate and heart rate training zones.

(By the way, forget the “220-age” formula you see on many pieces of exercise equipment. That formula is not based on original research and has been shown to have large prediction errors, particularly in older adults.)

One of the most popular HRmax calculations is called the Karvonen method. This calculation uses your age, sex and resting heart rate. The resting heart rate is an average of your morning heart rate (before getting out of bed) over several days. These steps will give you the HRmax and training zones:

1. Your estimated HRmax is 220 minus age if you’re male, and 226 minus age if female.
2. Calculate your Resting Heart Rate (RHR) by averaging your morning heart rate over several days.
3. Calculate your Heart Rate Reserve (HRR) by subtracting the RHR from your estimated HRmax.

Now calculate your training zones by adding a percentage of RHR to the HRR:

You’re not done with the calculations yet though; what you have here are your running training zones. In triathlon training, you have to adjust because of the different muscles involved and particularly the reduced effects of gravity when your body is supported by the bike or by water. Subtract 10 beats per minute from each running zone for cycling, and subtract 15 bpm from each running zone for swimming.

The scientific literature gives us two more ways to estimate HRmax based on age. In 2001, Dr. Hirofumi Tanaka from the Department of Kinesiology and Applied Physiology, University of Colorado at Boulder, proposed the HRmax formula of 209 – (0.7 × age). This was developed from a review of 351 studies involving over 18,000 subjects, and then validated with laboratory testing of 514 healthy subjects. The 209 – (0.7 × age) formula held for both men and women, and was not influenced by a wide range of physical activity levels.

In 2012 researchers from the Norwegian University of Science and Technology proposed a different age-related formula. Reviewing data collected from 3,320 healthy men and women over a two-year period as part of the HUNT Fitness Study (a sub-study of a large, population-based health study in Nord-Trøndelag county, Norway), researchers proposed a new HRmax formula, 211 − (0.64 x age). This formula offered significant predictive value regardless of gender, level of physical activity, VO2 max level or BMI.

To help you calculate your training zones, you can use the accompanying Excel spreadsheet. Simply enter your age, sex and resting heart rate measurements, and you’ll see the five training zones as calculated by the Karvonen method, the Tanaka formula and the HUNT formula. And the Borg Rate of Perceived Exertion table. Whichever you use, get out there and train with purpose!

References

Borg, G. (1998). Borg’s perceived exertion and pain scales (Vol. viii). Champaign, IL, US: Human Kinetics.

Gale Bernhardt. (2007). Training Plans for Multisport Athletes (Second Edition). Boulder, Colorado: VeloPress.

Joe Friel. (2004). The Triathlete’s Training Bible (Second Edition). Boulder, Colorado: VeloPress.

May2002JEPonline. (n.d.). Retrieved February 12, 2016, from https://www.asep.org/asep/asep/May2002JEPonline.html

Nes, B. M., Janszky, I., Wisløff, U., Støylen, A., & Karlsen, T. (2013). Age‐predicted maximal heart rate in healthy subjects: The HUNT Fitness Study. Scandinavian Journal of Medicine & Science in Sports, 23(6), 697–704. http://doi.org/10.1111/j.1600-0838.2012.01445.x

Physical Activity for Everyone: Measuring Intensity: Perceived Exertion | DNPAO | CDC. (n.d.). Retrieved February 12, 2016, from http://www.cdc.gov/physicalactivity/basics/measuring/exertion.htm

Robert A. Robergs, & Roberto Landwehr. (2002). THE SURPRISING HISTORY OF THE “HRmax=220 - age” EQUATION. Journal of Exercise Physiology Online, 5. Retrieved from https://www.asep.org/asep/asep/Robergs2.pdf

Tanaka, H., Monahan, K. D., & Seals, D. R. (2001). Age-predicted maximal heart rate revisited. Journal of the American College of Cardiology, 37(1), 153–156. http://doi.org/10.1016/S0735-1097(00)01054-8

Ken Johnson is a USA Triathlon Level I Certified Coach and writes on triathlon and endurance sports for examiner.com. Ten years the triathlon coach at the largest municipal fitness center in the U.S., he is currently a health coach in the corporate wellness field. He can be reached at ken.johnson.writer@gmail.com.

The views expressed in this article are the opinion of the author and not necessarily the practices of USA Triathlon. Before starting any new diet or exercise program, you should check with your physician and/or coach.