Five Reasons NOT to Train With Heart Rate.

"Despite the increased ease of heart rate measurement through the development of wrist-based sensors, many athletes and coaches have moved away from heart-rate-based training."



1. Cardiovascular vs Metabolic

2. Cardiovascular vs Mechanical

3. Pacing at the start of a race (short or long)

4. Training load for intervals

5. Reliability with wrist-based heart rate



Heart Rate Defined.


The term “heart rate” describes the frequency (in beats per minute) at which the heart is beating at a given point in time. Combined with the stroke volume (the amount of blood ejected from the heart per beat) it determines the total quantity of blood being pumped from the heart to circulate around the body per minute (the cardiac output). Blood carries oxygen and fuel to the muscles and removes carbon dioxide as a waste product. At rest, our need for this process is low, so the heart can beat relatively slowly to fulfill requirements. However, during exercise, the demand for blood increases dramatically, and, as the ability for stroke rate to increase is low, this is primarily met by increasing heart rate, making heart rate a good indicator of how hard the body is working to produce energy. Consequently, heart rate has been used by athletes and coaches for several decades to objectively measure exercise intensity and prescribe training.


However, despite its advantage over earlier training metrics, such as perceived exertion, heart rate is not a perfect training tool. In fact, despite the increased ease of heart rate measurement through the development of wrist-based sensors, many athletes and coaches have moved away from heart-rate-based training in recent years with the rise of alternative training devices, such as running power meters.

Following this trend, we outline five reasons why heart rate shouldn’t be your key training metric.


First, a recap of some important terms:


  • Heart rate (bpm). The number of heartbeats per minute.

  • Stroke Volume (Liters). The volume of blood pumped out of the heart per beat.

  • Cardiac output (L/min). The volume of blood pumped out of the heart per minute.

  • Cardiac output (CO) = Heart Rate (HR) x Stroke Volume (SV)