Ah, the ol’ “my resting heart rate is slower than yours, therefore I’m a superior athlete!” argument. Cyclist Miguel Indurain famously had a resting heart rate of 28 beats per minute, and he won the Tour de France five times in a row, so it’s easy to see how one might think the lower the resting heart rate, the fitter the athlete. Lucky for you, it’s somewhat true.
“As a general principle, the harder you train, the more effect you’ll see on the resting heart rate,” says Dr. Thomas Allison, director of stress testing at the Mayo Clinic in Rochester, Minn. “With exercise, the heart gets bigger so it pumps more blood with each beat. People that exercise a lot can lower their resting heart rate by 20 to 30 beats.” In other words, you can train your heart to work more efficiently by exercising.
But training isn’t the only thing that will affect how low you can go. Genetics also influences resting heart rate, though researchers are still figuring out to what extent. So it’s possible you’ve simply inherited a predilection toward a lower resting heart rate that your buddy does not share.
And while you might win a theoretical Who’s Fitter argument with a heart rate monitor, your buddy could still cream you in competition.
“Just because person A has a lower resting heart rate than person B doesn’t mean person A will beat person B in a race,” Allison says. Person B, your buddy in this situation, might be stronger all-around, or have more fast-twitch muscle fibers that will help him whoop you in a sprint, after which we would not fault him for turning around and shouting at you, “Who’s fitter now?”
(Note: The American Heart Association pegs the average resting heart rate between 60 and 80 beats per minute. Besides genetic and training influences on resting heart rate, there’s also the influence of disease. People with low resting heart rates who do not train should have their doctor check them for cardiovascular disease.)