• Mark Turnbull

The difference between monitoring training intensity with power and heart rate

Updated: Jan 7



There is one big difference between power and heart rate that carries great practical implications when monitoring the intensity of your workouts.

Power is a split second expression of the absolute external load to your system right now. In contrast, your heart rate is a compensatory mechanism that adjusts depending what the oxygen demand is on your muscles over a period of time. Compared to your power output, this mechanism can fluctuate depending on the clients fatigue, hydration, temperature and there is also a delay when matched against watts. As a result, when you increase your watt output, it takes some time before your heart rate increases enough to sufficiently reflect the resulting increase in oxygen demand. Using recommended heart rate values to guide a high intensity interval training session, you normally cannot expect to reach the recommended HR values for the higher intensity zones until quite some time into your session. By comparison, recommended power values (% of FTP) can be reached immediately, and maintained throughout each interval in its entirety. This makes the power meter a more effective tool to gauge the intensity of your interval training by. An even stronger level of certainty is of course achieved by monitoring both power output and heart rate simultaneously.

Why you will benefit from monitoring your training intensity


These days the majority of keen cyclists use power meters and heart rate monitors to monitor intensity during your workout.



However, research suggests that rating your perceived exertion (RPE) on a scale from 6-20 can regulate training intensity just as well as a heart rate monitor (11-12). RPE method is used by cycling coaches when conducting ramp and MAP tests on cyclists. I would also make the case that having a good (RPE) has the added benefit of gauging your effort in a race situation. At the end of the day you have to make split second decisions on the road and power can be all over the place, glance down and it could be 400w 2 seconds later 280w. RPE is essential in these situations and is for the majority of race situations you watch on TV. Yes, use the power file after the race, but to know yourself through repetition and routine in your training intensity is critical. Training stimulates different physiological pathways depending on your exercise intensity. Low-intensity training has a different effect on your body than does high-intensity training. Different intensities also require different post-workout recovery duration. What is more, there is compelling data to suggest how to organise your training between different exercise intensities. As a cycling coach will provide training plans built around ‘A’ races and structured progression towards these goals with specific training and recovery. The benefit of working with a coach and recording your training intensity is twofold:

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