Learn to feel the right effort by heart rate

Heart rate is different. It is measured, not felt. That is what makes it useful. It gives you an outside check while you learn the inside signs. Once you have learned them, you can hold each effort by feel, with or without a watch.

Heart-rate efforts are percentages of your maximum. If your maximum is wrong, every effort is wrong with it. The usual shortcut is a formula based on your age. One is 208 minus 0.7 times your age. It is a little better than the older one, 220 minus your age, which was never based on research. For a typical person, both are off by about ten beats either way. For some people, they are off by 20 or more.

Find your own peak with a hill test instead. It gives you your number, not the average person's. It is the peak you reached that day, so do it fresh. On a tired day, it will read low.

With your maximum, you can find each effort on foot. Base is 65 to 80 percent of your maximum. Threshold is 85 to 92 percent. VO2 max is 92 to 100 percent.

Now use the number to calibrate the feel. Run in each range and pay attention. In the base range, you should be breathing in and out through your nose, and you could keep going for hours. At threshold, you breathe in through your nose and out through your mouth, and you could hold it for about 20 minutes, not much more. At VO2 max, you breathe in and out through your mouth, and you could keep it up for a few minutes.

Remember what it feels like. That memory is what you are really training. On hard efforts, give the number time. Heart rate is slow to catch up when you start working hard. It can take a couple of minutes to settle. So on short, hard efforts, read it near the end, not at the start.

The same effort gives a lower heart rate on a bike than on foot. In one study, 143 triathletes each did a running test and a cycling test in a lab. At the point where easy turns into moderate, their heart rate was about 10 to 13 beats lower on the bike. So the riding ranges sit lower. Base is 62 to 76 percent of your maximum. Threshold is 82 to 89. VO2 max is 89 to 96. Never take a running number onto the bike.

In the water, heart rate is lower again, and it is a weak guide. Use no heart-rate range for swimming at all. There, how long you could keep going is your reference. That is another reason to learn the feel on land first. You take it with you into the water.

Your pace, or your power on the bike, measures what you produce. It tells you how fast you are moving. Your heart rate measures what that costs you. That cost is your effort. They are not the same thing, and the difference matters every time you train.

The same pace costs more uphill. It costs more into the wind, on rough ground, and in choppy water. It costs more on a hot day, and late in a long session. The conditions change what a pace costs. So on those days, holding your usual pace means working harder than you planned.

Heat shows it clearly. In one lab study, seven trained cyclists rode at a steady power in 35-degree heat for just over two hours. Drinking as they rode, their heart rate still rose from about 147 to 158. On a day they did not drink, it rose from 150 to 186, close to their maximum. The power never changed. The effort climbed the whole time. This is called cardiac drift.

Your body does not know your pace. It knows how hard it is working. That is what builds your fitness, and that is what tires you out. So the effort is what you train, and the speed is whatever the day gives you.

Hold the effort and let the pace go. Slow down on the climb. Slow down into the wind, on the trail and in the heat. Your heart rate shows you the effort from the outside. Your breath, and how long you could keep going, show it to you from the inside. When they all say the right effort, you are doing the right session, whatever the watch says about your speed.

A slow day is not a bad day. A base run up a mountain is still a base run. A threshold ride into a headwind is still a threshold ride. The effort was right, so the training was right.

Find your maximum. You need a hill, a heart-rate monitor and 20 minutes on a fresh day. Jog easy for four minutes, then fast for four. Then run three all-out climbs of two and a half minutes each, jogging back down between them. Your maximum is the highest heart rate you reach.

Find your base effort. On your next base run, stay between 65 and 80 percent of your maximum. Notice your breath and how long you could keep going. On a hilly, windy or hot day, hold the effort and let the pace drop.

Find threshold and VO2 max the same way, in the sessions where they belong. Each time, match the number to your breath, to how long you could hold it, and to how hard it feels.

Then check the monitor less. Guess the effort first, then look. When your guess keeps matching the number, you have learned it.

What you get is a feel for every effort that you can trust, in any sport, on any day and on any ground, with or without a watch. Your base sessions stay base, and your threshold and VO2 max sessions hit the right effort. And you can train again tomorrow. Consistency is king in endurance sports.

• Price et al. 2022. International Journal of Environmental Research and Public Health 19(6):3557. Heart rate in running and cycling tests, 143 triathletes.
• Olstad et al. 2019. Maximal heart rate for swimmers. Sports 7(11):235. 12 elite swimmers.
• Robergs and Landwehr 2002. Journal of Exercise Physiology Online 5(2):1-10. The history of the 220 minus age formula.
• Tanaka, Monahan and Seals 2001. Journal of the American College of Cardiology 37:153-156. The 208 minus 0.7 times age formula.
• Kasiak et al. 2023. Journal of Clinical Medicine 12:2884. How far age formulas miss in athletes.
• Lai et al. 2016. Physiological Reports 4:e12970. How fast heart rate responds to harder work.
• González-Alonso, Calbet and Nielsen 1998. Journal of Physiology 513:895-905. Heart rate over two hours of cycling in the heat.