Thursday, August 26, 2021

Target Heart Rate

It’s Just a Number, After All 

For decades the accepted wisdom for maximizing cardiovascular fittness levels has been the “target heart rate” defined very simply and roughly as 80% of your age subtracted from 220. 

In a formula, ( 220 - age ) * 0.8. 

For example: 

  • For a 20 year old ... 200 * 0.8 or 160 
  • For a 50 year old ... 170 * 0.8 or 136 
  • For an 80 year old ... 140 * 0.8 or 112 

You can see that for every 10 years of increase in age, target heart rate drops by 8. 

This target heart rate is an ideal to maximize the beneficial cardiovascular effects, it’s not the minimum before any beneficial effects occur. 

This point is the single most important thing to understand about cardiovascular exercise:  any kind of movement is a good start and will be better for you than sitting on your butt. Going beyond that is fine tuning for personal goals, whatever those might be. 

Benefits occur within a range. You will definitely still realize some benefit from hitting 70%, or 60% — probably even 50% — as long as you do it long enough, compared to a baseline of sitting and doing nothing.

This debate often shows up in opinions on whether or not walking “counts” as cardiovascular exercise. Just asking the question is evidence of a classifcation error for people under the spell of counting and measuring, and “data”, and studies, and every damn thing under the Sun except for the only thing that matters: trying it and evaluating what it does for you.

Active is active and your body doesn’t much care what you are doing, as long as you are somehow moving your legs, which are by far the biggest muscles in your body and kick the entire cardiovascular machinery into gear. Leg exercise also engages your core — glutes, abdominals, lower back, hip flexors, pelvic floor, etc.

Leg exercise of any kind *is* cardiovascular exercise, as long as you do it long enough. 

I fell victim to the “what good could walking possibly do, it’s too easy” fallacy myself, until I actually ... you know ... tried it. In the winter of 2010 or 2011, after years of knowing I missed outdoor exercise during the winter (I like biking in warmer weather), I decided to try walking 30 minutes or more several times per week, in the middle of the day during the best daylight hours, as part of a lunch break, and see what happens.

I was impressed and amazed at the energy and focus I gained afterward, the mood improvement, and then — a most welcome surprise — the improvement in sleep quality. It was quite the discovery and really opened my eyes to the benefits of moving your legs, for long stretches of time, even at lower intensity levels — much lower than we’ve been taught are required.

Sleep quality! It was life-changing. Just from walking 30 minutes at 2pm. Who knew? 

Key point: I only discovered this by doing it myself and learning how it helped me. 

I didn’t pay any attention to target heart rate, either. I just treated it like an activity break, as much for mental and emotional recharging as anything else. And yet, the other benefits were obvious and pronounced. I became a big fan, and have been walking ever since, along with biking and other activities. And I do not stress about counting steps, or target heart rate, at all.

Target heart rate is of course a fine concept and we need it to have something to aim towards, especially for cardiac patients and the ultra-competitive among us. But at the end of the day, it’s a very simplistic, rough guideline based on the idea that, well, people need a number to aim for, so let’s give them one. It’s not magic and it’s not a mimimum, and it obscures the more important divide, the only divide that really matters: sedentary vs. active. All else is details.

I’ve learned a lot over the years about exercise, and I can say with confidence that there’s just something magic about moving your legs at a steady pace, outside, for at least 25 minutes, that produces real results for your entire cardiovascular sytem plus better sleep quality, mood, energy, focus, and more. 

You may find these same results, or they may be different, but either way, you really should try it for yourself and stop listening to people’s opinions about what “counts” as cardiovascular exercise. It’s your heart, you own the condition it’s in, and you want to keep it healthy as long as you can.

Dr James Meschino does a great job of explaining this.

Here’s the Cleveland Clinic on the benefits of aerobic exercise and how to realize them — they say as little as 30 minutes a week will at least help a little bit, and I have no reason to doubt it.