Use Lactate Threshold instead of Maximum Heart Rate

My report on the unreliable Maximum Heart Rate formula brought many questions on how heart rate SHOULD be used for training. Competitive athletes often use a guide called lactate threshold (LT). When you exercise, your muscles require oxygen to convert food to energy. If you exercise so intensely that you cannot get enough oxygen, lactic acid accumulates in your muscles and spills over into your bloodstream. This makes your muscles more acidic which causes terrible burning, and you to become short of breath and slow down as you struggle to get more oxygen. Your lactate threshold occurs when you exercise at the highest average heart rate you can maintain for 45-60 minutes. offers the following guidelines for cyclists; the same principles can be used in any other endurance sport.

"A good way to find your LT is to ride a fairly flat 15-mile course at a hard pace. Use a heart monitor that averages heart rate for the distance or just check it occasionally to see where HR settles.

You'll quickly find that you can maintain a certain high HR, but if you go a few beats higher you'll start panting and be unable to control your breathing. Trial and error will reveal the highest HR you can maintain for the distance. That's your LT.

Three simple exercise zones based on your LT heart rate are sufficient. These guidelines should work for most riders:
Recovery takes place about 40 beats below LT
Endurance is built on rides about 25 beats below LT
Breakthrough training is done from 10 beats below LT to about 5 beats above LT
No heart monitor? You can do just as well by monitoring your perceived exertion. For instance, recovery rides should be so easy that you barely feel the pedals. The idea is to take a 'walk' on the bike. Hard efforts, such as intervals and climbing, should be at the limit separating steady-but-labored breathing from panting and gasping. By experimenting you'll find this LT boundary."

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