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How I Calculate Your Training Zones

Ok so I’ve seen a few different training zones from different apps such as Training Peaks, Peloton, and Garmin. I use the ones from Ironman University, because that is my certification and it is super easy for athletes to follow. Below are the IM training zones based on %THR Run and %THR Bike. I am going to show you how I calculate my athlete’s training zones based on these numbers.

A field test can be performed to find the point at which an athlete’s body is producing more lactate than it can remove, the lactate threshold. This is done at the track with a 30 minute effort as follows.

The other option for this test is to do it at the exercise lab on the treadmill. I take local athletes to the lab here at Texas A&M for this test. They wear a mouthpiece that captures VO2 max as well as LTHR for run (or bike). The test for the run involves starting out very slow and progressing to a steeper hill and a faster pace until the athletes can’t hold on any longer. This test captures a lot of data, but most importantly, the athlete’s lactate threshold heart rate.

The results of this test are used to assign training intensities based on a percentage of heart rate at the predicted lactate threshold. For example, Rob is a 42 year old male athlete with a lactate threshold HR of 157. Here are his run training zones:

For the bike, power is a common method of measuring intensity for cyclists and is expressed in watts (force, or how hard the athlete pushes on the pedals) multiplied by angular velocity (cadence). Functional threshold power is the exercise intensity at which the athlete reaches a predicted lactate threshold. There are a few options on how this number is achieved. The athlete can do either a 20 min test or a one hour test on the bike. Percent FTP can be used as a measure of training intensity for the bike.

So, using the same example of Rob, his FTP after testing is 168. Using that number, I calculated his bike training zones as follows:

Throughout an athlete’s Ironman program, they progress from the easier aerobic zones to moderate to threshold and above. The majority of an athlete’s workouts for the entire program are mostly in the aerobic to moderate aerobic zones (Z2/Z3).

I hope you found this article helpful for helping you calculate your training zones. Are you thinking about hiring a coach for your next iron distance event? Set up a FREE 15 minute chat with me by clicking the box below with your name and phone!

Mary Timoney

Ironman University Certified Coach

USA Cycling Coach

ACSM Trainer


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