Mistake #2: Using Your HR Monitor During Speed Workouts
Heart rate monitors are not useful in high-intensity interval workouts featuring individual efforts lasting one minute or less. That’s because of a phenomenon called cardiac lag. When you suddenly increase your exercise intensity, it takes a while for your heart rate to climb to the level at which it will ultimately plateau. Therefore, in short, fast intervals, you may find your heart rate climbing most or all the way through each. In this type of workout, it’s best to use pace and perceived effort to regulate your intensity.