“From a perception standpoint, your LTHR is the point where you can’t speak very easily anymore while you are working out.”
Heart rate training experts will often say there is no such thing as a Maximum Heart Rate- instead, it is the point where your body starts to operated at its’ Lactate Threshold Heart Rate (LTHR) that you should be paying attention to.
Why? Because that is the point where your muscles are starting to build up more lactate as they are unable to clean out or burn. This build up will inhibit the ability for the muscle to function properly, and most people can operate in this zone only for a brief time. You can set your strategies for a race based on the length of the race and your current LTHR, for longer ones making sure you stay below LTHR until the end, or shorter where you want to be at and even above your LTHR as you go full out.
For ease of comparison, we equate your Lactate Threshold to be the 85% Max HR level, or the middle of Zone 4, for most people in good shape. The less in shape you are, the more potential your LTHR is less than 85%. From a perception standpoint, your LTHR is the point where you can’t speak very easily anymore while you are working out.
For a great workout to determine your Lactate Threshold, Fitdigits apps include a Critical Power 30 minute fitness assessment, based on the uber-heart rate training expert Joel Friel blog on the subject (requires performing at the maximum of your ability to maintain for 30 minutes, at a 30 minute maximum race pace). While the assessment is intensive, it should provide, especially over multiple times, an excellent basis for determining your heart rate training zones.