You Are Better than Your Fitbit

I am now going to add you to an exercise experiment—with one caveat. For the purpose of this experiment, everyone is 50 years old. If you are younger, I am sorry, you are now 50 years old. If you are older—and far too wise to participate in such trivial nonsense—then I am sorry, you are now 50 years old.

The first person in your group is 5'4" and weighs 200 pounds. She has a high fat mass, a low muscle mass and a limited history of exercise.

The second person is 5'10" and weighs 160 pounds. He has low fat mass and low muscle mass. He has asthma from smoking and has survived one heart attack.

The third person is 6' and weighs 165 pounds. She has low fat mass and high muscle mass. She is a world champion masters rower.

The fourth person is you. You are X tall and weigh X pounds. You have X fat mass and X muscle mass. Your exercise and dietary habits are X. And you are 50 years old. Again, sorry.

For this experiment, all four of you will go see your physician for an exercise prescription. Granted, you don’t have the same physician, and that’s OK because, since 1970, doctors have generally been following the same guidelines for cardiovascular health. Your physician points toward an exercise poster on his wall that shows a heart rate intensity graph based on your age. He shows you on the graph that your heart rate, during exercise, should be 119 beats per minute, representing 70 percent of 220 minus your age. Based on the work of doctors Fox and Haskell circa 1970, this is gospel—and this gospel is embedded in the electronics of countless gym machines that will squawk at you if you don’t follow it.

But you tell me, based on you and the other three people in this experiment, does this make any sense? I think not, and I hope that you think not. A few years ago I implemented a postcardiac rehab program with a nearby hospital and every patient was given an expensive heart rate monitor, so we had the opportunity to test the 220 minus age formula. It did not work—at all. It was too hard for most, too easy for some, and for others on medications like beta blockers it was simply impossible.

We now know that hearts, like people, come in different shapes and sizes. Some hearts perform optimally at very high rates and some at comparatively low rates. One type of heart isn’t better than the other. It is simply that they are different. So we got rid of the heart rate monitors.

So what do we do? Well, the answer is wonderfully simple, and it’s called RPE, Rate of Perceived Exertion. It’s a scale from one to 10. One is breathing. Ten is barely being able to catch your breath. One is sitting on the couch eating Cheetos. Ten is sprinting up a hill with the couch on your back and the Cheetos cheetah on the couch snarling. You get to create your own metaphor, your own one to ten10. That’s part of what makes it so brilliant. The other part is that the scale automatically adjusts to your body and your physical condition from one moment to the next.

Now here is the equation for basic aerobic exercise: Your effort level should be 3–4 out of your 10. Not 5, not 6, not the intensity of the guy working out next to you because your ego is threatened, not 9 because the girl next to you is inadvertently threatening your masculinity, and not necessarily the same pace that your 3–4 was yesterday. It’s 3–4, right this moment.

This 3 to 4 pace may seem too easy to some, and it is somewhat counterintuitive to our “more/harder/better” culture, but less stress actually leads to more adaptation and more fitness. Adaptation trumps stress, and this has been proved, time and time again, even at the Olympic level.

So if you want to train effectively and at the right intensity, dial in to a conversational pace of 3–4 out of 10, and know that you are training smarter, at a seemingly lower intensity, while achieving better results. Sing a few lines of a favorite tune while you exercise. If you can’t, you’re working too hard.

Because a Good Life Involves Intervals of Exertion

Let’s say your basic exercise is on a stationary bike or is a walk in the park. After about 10 minutes at your RPE of 3–4, increase your pace for 15 seconds to an RPE of 5–6. Then return to your RPE 3–4 pace for 45 seconds. Repeat that for a total of three to five sets. Congratulations! You have just completed a High Intensity Interval Training session with a work/rest ration of 1:3.

You can manipulate a HIIT session by fiddling with three variables: the volume of work, the ratio of work to rest, and the intensity of the work.

If you are exercising aerobically five days a week, add one or two HIIT sessions per week at an RPE of 5, maybe Tuesday and Friday. After a couple of weeks at 15 seconds on/45 seconds off, increase to 30 seconds on/90 seconds off. You have now changed the volume of work while maintaining the same work/rest ratio of 1:3. After a couple more weeks, switch to 30 on and 60 off. Now you have changed the work/rest ratio to 1:2. Next try the same thing at an RPE of 6, changing the intensity. Books have been written on the best formulas, but you don’t need them. Just tune in to your own body and play.