I usually ride with a heart rate monitor. I have a screen on my Garmin that shows, among other things, my heart rate.
I know the disadvantages of using a heart rate monitor. Such as heart rate being affected by ambient temperature, your emotional state, whether you are tired, or whether you are over-trained. The monitor itself can generate spurious data.
Nevertheless, my heart rate monitor gives me some data to quantify my level of effort, and more importantly, it tells me when I need to back off, or run the risk of blowing up. Over time I have learnt that 160bpm is when I need to back off.
I could use a power meter instead. Power output is a more precise way to gauge performance than heart rate is. However a power meter is too expensive, despite where prices have fallen to, given the non-competitive riding that I do.
I got to 157bpm last weekend, for the first time in ages. It was at the end of a 500 meter, 7.1% average gradient climb. That climb came after 110km / 68mi of riding at about 32kph / 20mph. Faster than I normally ride, so cardiac drift had already pushed my average heart rate to about 140bpm.
The highest I got to the the six weeks prior was 155bpm, during the 141km / 88mi CIMB Cycle @ Seri Menanti event. That ride had 1,100 meters / 3,600 feet of climbing.
Soon after the CIMB ride I went on holiday for a fortnight or so. I ate a lot, and did minimal exercise. It was a holiday after all. But I was still very surprised when my Garmin showed 160bpm on my first ride after that holiday.
Six days later I did another ride, and I hit 164bpm. My maximum heart rate during those two rides was about 20bpm higher than is usual for me. What was going on?
For better or for worse, I went to Google for answers. Google didn’t tell me anything I didn’t already know. Fatigue, overreaching, overtraining, too much caffeine, or a hot day could all be reasons why my heart rate rose above what I normally see.
I didn’t have any of the symptoms which would set off alarm bells, such as lightheadedness, nausea, or pressure, pain or discomfort in my chest, arm, neck or jaw. Still, I wondered.
I needn’t have worried. I went on a 70km / 43.5mi ride the next day, and my maximum heart rate was 125bpm. Since then I have maxed out at an average of 147bpm, including last weekend’s outlier.
So what caused that two ride blip? I’m not sure. Probably a combination of jet lag and low blood sugar.
It is time for my annual physical exam. Just to be on the safe side.