Not long ago, my sister-in-law threw down the gauntlet and issued a “lockdown challenge” to see who could run 5 kilometers (3 miles) the fastest.
I ended up doing it in a little over 25 minutes, which I was reasonably happy with given that I’m not much of a runner.
What’s interesting (to me, anyway) is what happened to my heart rate, which averaged 178 beats per minute during the run. At one point, it got as high as 191 beats per minute.
So what does all of this have to do with you?
There are many different formulas for calculating your maximum heart rate. This in turn is used to create specific training zones that help determine exercise intensity during a given workout.
Back in the day, your maximum heart rate was estimated by subtracting your age from 220. At 20 years old, your theoretical maximum heart rate is 200 beats per minute. At 40 years old, this would be down to 180 beats per minute.
Problem is, the 220 minus age formula was never particularly accurate. At the age of 46, my theoretical maximum is 174 beats per minute – a lot lower than the 191 I hit during my run.
Even the guys who came up with the formula back in the 1970’s – William Haskell and Sam Fox – never intended it to be used as an absolute number for athletes or people who are training hard.
“I’ve kind of laughed about it over the years,” says Haskell. “It’s typical of Americans to take an idea and extend it way beyond what it was intended for.”
In 2001, Dr. Douglas Seals, an exercise physiologist at the University of Colorado, tried to come up with a more accurate formula, gathering data from 351 published studies involving 18,712 people. He also included data from a number of his own studies involving 514 men and women.
His research, published in the American Journal of Cardiology, shows that the traditional formula of 220 minus age overestimates the maximum heart rate in young adults, does a reasonable job for people who are around forty years old, and then becomes less accurate as people get older.
A much more accurate formula, he says, is 208 minus age times 0.7 (HRmax = 208 – 0.7 x age).
But even that’s some way off accurately predicting my maximum heart rate. If I plug my age into the formula, it gives me a number of 176 – 15 beats per minute off the high of 191 I hit during the run.
The formula that came closest to predicting my maximum heart rate was the HUNT formula, which involves multiplying your age by 0.64 and then subtracting it from 211.
That puts my maximum heart rate at 182. Closer than 174 and 176, but still not entirely accurate.
The only way to find your real maximum heart rate is with an exhaustive exercise test, which hardly anyone bothers with.
Despite this, many people are still using an age-based formula to calculate their training intensity. While it might all look very scientific and official, it’s not too useful if it’s based on the wrong number.
If you do want to add some cardio to your training program, I think you’re better off cycling rather than running.
For one, as long as you’re not doing too much of it, cycling will have little to no adverse effect on muscle growth.
In fact, there are a few studies to show that the addition of cycling to a resistance training program improves rather than impairs gains in muscle size, which is why it makes a great companion to my MX4 training program.
It’s also a very “joint-friendly” form of exercise. Even with a dodgy knee, I’ve been on week-long cycling expeditions to the Julian Alps in Slovenia and Spain’s Sierra Nevada without it playing up.
Christian Finn, M.Sc.
Founder of Muscle Evo