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QOTW: How Do You Figure Out Your Lactate Threshold?

This week’s question came to use from Reddit user Reddit_at_work91 who asks

I want to get a bit more accurate on my bike workouts (have just signed up to my first full next year), and thought some lactate threshold intervals would be worthwhile. What’s the best way to figure my lactate threshold heart rate out?


You’re smart to start out training with properly testing your zones! If you look at any forum where new triathletes gather whether it be redditbeginner triathlete, or even Slowtwitch, there still exists much confusion over the use of heart rate and the proper use of zones. I am consistently surprised by the number of people who use the default Garmin Connect zones in their profile as gospel. These zones are calculated off of max heart rate and are virtually meaningless unless you get lucky and happen to have both the same max and derivative zones in their formula.


Now that wrist heart rate has brought  more common this issue of using heart rate without context has become more common, as many athletes who may not be interested in the science of training now have heart rate information readily accessible. Thus, it is not unusual to hear athletes claiming to do all their runs in zone 5, perform three hour rides at an IF of 1.2 or other impossible feats.


In order for heart rate to mean anything,  you require a north star and that star is your lactic threshold heart rate. There are a few good ways to find this value, which by the way, will likely be different on the bike versus the run. If you don’t have a coach to help you, then consider getting a lab test to help you get started. If you’re on your own, check out Joe Friel field tests to get a good sense of where you’re at. Or, if you’re local and training with us, hit up an Energy Lab FTP test (happening the last week of each month) to get a good estimate of your cycling lactic threshold heart rate.


There is much to be said about zone training after you’ve properly set your zones. But the first step is getting both your run and cycling zones, nailed down accurately. Happy training!



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