The most common wisdom was to subtract your age from 220, and – voilà! – you had your max HR, a figure representing the greatest number of beats per minute your heart can achieve.
Then, from that number, you could allegedly calculate your recovery, fat-burning, lactate threshold and anaerobic heart-rate training zones.
However, it’s a rudimentary system – like, “might as well use an abacus as a bike computer” rudimentary.
“It’s been the standard for years but there are a lot of variables” that can throw off your max HR, says Cherie Miner, MD, a sports medicine physician and age-group Ironman athlete at Andrews Sports Medicine and Orthopedic Center.
She adds that how fit you are, how hot it is, and how much stress you’re under can all affect your max HR at any given time.
Like the 220-minus-age rule, there are a lot of other myths surrounding max HR. Here, we debunk the worst of them.
1. If you go over your max HR, your heart explodes
You’ve got to admit, this would be horrifying if true. Rest easy, though – it won’t happen.
“Your heart gets to the point where it can’t eject blood effectively enough; where it’s not productive anymore,” says Dean Golich, head performance physiologist for Carmichael Training Systems.
When this happens, self-preservation kicks in and you slow down. If you’re in a race, that means you’ll either just get dropped or toss your cookies.
“Most people have one to two minutes max at their max HR; highly trained athletes may have more,” says Miner.
Expect to see your performance suffer very quickly if you try and maintain your max HR for more than just a short burst.
2. Your max HR is the same for everyone your age
That’s what the old-school formulas assume, but Golich says it’s much more nuanced than that. Max HR is largely untrainable, and determined by genetics – some of us have hearts tuned like humming birds’ while others have the slow and steady type.
“But it’s not an indication of performance,” Golich says. “If your max is 200 and someone else’s is 190, it doesn’t mean one of you is the better athlete.”
In fact, he’s worked with numerous talented athletes at both ends of the spectrum.
It’s good to remember that everyone’s max HR does drop as they age – but again, that doesn’t mean you’re losing fitness. Regular training and good nutrition will affect performance more than the fact that your max HR is now slightly lower than it was three years ago.
In reality, it’s not your max HR that determines your fitness level: Being able to hold your max HR for longer and longer sessions is what’s key.