The Case Against Monitoring Heart Rate
Heart Rate Is Not A Super-Reliable Metric Of Exercise Intensity
Strap on a heart rate monitor and ride a rollercoaster. As you fly along with a death grip on the safety bar, your heart rate will climb near its maximum. Does that mean you’re getting a great workout? No, it means your sympathetic nervous system is highly stimulated, just as it is likely to be during races, which is why heart rate is often 10+ BPM higher in races than it is at the same work output level in workouts.
For this reason, you can’t trust heart rate to properly control your pacing in races. My greater point is that your heart rate is affected by a variety of factors besides exercise intensity, so it’s a dubious choice as the metric by which to measure and control exercise intensity.
Heart Rate Training Formulas Are Iffy
Every heart rate-based training system relies on the use of formulas to establish target heart rate zones for different types of workouts. Even the best of these formulas are too one-size-fits-all to establish truly custom-fitting intensity targets.
For example, some systems assume that every athlete who has a threshold heart rate of 168 has a VO2 max heart rate of 175-179, but that’s not true. Heart rate profiles are very different from one athlete to the next, even when there is some overlap, making the use of one-size-fits-all formulas dubious.
Heart Rate Monitoring Is Useless At Very High Intensities
You can’t effectively use heart rate to monitor and control the intensity of very fast intervals, because the heart rate climbs throughout them. Anytime there is a sudden, drastic increase in exercise intensity, there is a substantial cardiac lag that makes the numbers on your HR monitor display not worth paying attention to.
Heart Rate Is Not Performance-Relevant
In my opinion, the greatest flaw of heart rate monitoring as a means of monitoring and controlling workout intensity is that heart rate is not performance-relevant. You can’t set heart rate goals that will help you race better. For this reason, heart rate is not a very motivating type of workout feedback. Pace and power are.
When you train sensibly with pace or power output as your primary form of feedback, you tend to push a bit harder in an effort to beat your previous standards. The introduction of this self-competitive aspect into training leads to faster progress.