Here in Tucson we have a 60- to 85-degree swing from one day to the next. I will see my HR go up 10+ beats at a given power. How does one account for heat when training to heart rate? —Ted Zuhlsdorf
Many factors affect heart rate: heat, fatigue, hydration, and cardiac drift to name a few.
This is where the art of training comes in. The best way to gauge your true intensity is to use a mix of three metrics: heart rate, power, and RPE (rate of perceived exertion).
There is a technique to “calibrate” the three metrics on your rides. First, make sure you’re warmed up and your power meter is calibrated. Then, ride at a wattage that normally feels just slightly hard – 120 to 200 watts or so. Hold it for a few minutes and monitor your heart rate response and RPE. You’ll quickly learn your typical heart rate and RPE for that intensity.
Once you’ve learned what’s typical, watch for variations. For example, if heart rate and RPE are normal, you’re good to do your training as planned. If heart rate is sluggish and the effort feels a lot harder than normal, you may be fatigued. If RPE is normal but heart rate seems high and it’s a hot day, then you just need to adjust your heart rate ranges up five to six beats per minute for that ride. And of course make sure you’re hydrating.
Seeing how those three metrics interact at a known wattage tells you a lot about where you’re at on that day and if you need to do anything to adjust your training or targets.
Trevor Connor is a long-time cycling coach and elite racer. He holds degrees in exercise physiology and nutrition from Colorado State University.