A less taxing option is to determine your lactate threshold heart rate by perceived effort. As I mentioned in the previous section, the lactate threshold heart rate corresponds to a rating of 6 on a 1 to 10 scale of perceived effort. So you can estimate your lactate threshold heart rate by starting a run at a perceived effort of 1 and then increasing your effort point by point until you give it a rating of 6. Your heart rate at this point is your lactate threshold heart rate. The downside of this test is that a little practice is needed to master the art of quantifying subjective effort.
