America's Energy Doctor
We all know exercise is important. But not everyone realizes that, where cardiovascular (aerobic) workouts are concerned, the intensity of your exercise is important to achieving the most health benefits. And the best way to know if you’re pushing yourself hard enough—and not dangerously hard—is to work up into your target heart rate zone.
Now, this doesn’t mean exercise that doesn’t get you there is worthless. Any physical activity is better than none. Plus, if you’ve been sedentary for a long time, if you’re significantly overweight, or if you have a heart condition or certain other conditions, it’s important to start out with just a little exercise—not too strenuous and not too long—and gradually build up your regimen.
I say it a lot, and I’ll say it again here: Please consult your doctor before you embark on a new fitness journey. Exercise is great, but there are risks of injury and overexertion, especially when you’re really out of shape. Your doctor can help you tailor a workout plan that’s safe and effective.
Here are all the basics about what you need to understand about your heart rate to maximize the benefits of your workouts.
Three Heart Rates
There are three heart rates to be aware of for this discussion:
- Resting heart rate refers to how many times your heart beats per minute when you’re not doing anything. You get the most accurate read when you first wake up, before getting out of bed. Generally, the better shape you’re in, the lower your resting heart rate. The average for adults is 60 to 100 beats per minute; very fit athletes average 40 to 60 beats per minute.
- Target heart rate is a window, not a single number. It represents how many times per minute your heart beats when you’re pushing your body to the most beneficial point of exertion during aerobic exercise.
- Maximum heart rate is an estimate of the upper limit of beats per minute your cardiovascular system is capable of.
Measuring Your Heart Rate
Taking your pulse is how you find your heart rate. For the most accurate measurement, get a stopwatch or timer.
With light-moderate pressure, place the tips of your index and middle fingers on your neck to the side of your windpipe or on the underside of your wrist, right below your hand and just slightly off center toward your thumb. Until you get used to it, you might have to move around a little until you feel the pulsations. Most people find it easiest to take their pulse on their wrist.
Count the number of beats for 30 seconds, then multiply by 2 to find the number of beats per minute. You can also just count for 20 seconds and multiply by 3, for 15 seconds and multiply by 4, or for 10 seconds and multiply by 6. You’re just finding the number of beats per 60 seconds. Counting longer gives you a more reliable measurement, though.
So, just for an example, if you count 20 beats in 15 seconds, your heart rate is 20 x 4, or 80 beats per minute.
Finding Your Target Heart Rate
Your target heart rate is a pretty big window, typically anywhere from 50 to 85 percent of your maximum heart rate. Again, your doctor may advise a lower target at first (and high-performance athletes may strive for 90 percent), but these are standard numbers.
Finding your maximum heart rate is easy. Simply subtract your age from 220. For example, if you’re 42 years old, your maximum heart rate is 220 – 42, or 178 beats per minute.
Moderately intense cardio exercise is considered a workout that elevates your heart rate to somewhere between 50 and 70 percent of your maximum heart rate. Intense workouts are considered those that get your heart pumping from 71 to 85 percent of your maximum heart rate.
To continue with our example of a 42 year old, let’s say he’s not in bad shape, but he hasn’t really worked out much in the last few years. He might start out aiming for the low end of moderately intense exercise, maybe 55 percent of his maximum heart rate. He needs to push his beats per minute to 178 x 0.55, or 98 beats per minute.
If all this math makes your head hurt, don’t worry. There are free heart rate calculators online. Try this one, which lets you input your age and target heart rate, then tells you the number you’re shooting for.
During Your Workout
You have to stop periodically during your workout to take your pulse and figure out the heart rate you’ve achieved. Because your heart rate starts dropping when you stop moving, keep it short and just take your pulse for 10 or 15 seconds and multiply by 6 or 4 respectively.
If you’re heart rate isn’t as high as it should be, step up the intensity of your workout; if you’ve overshot, take it down a notch or two.
Don’t get too hung up on the exact numbers, though. While you get precise numbers this way, our bodies can’t be reduced to a mathematical formula. Everyone’s different. People have naturally higher or lower resting and maximum heart rates. Also, some medications, like those for hypertension, lower your maximum heart rate. Anyone’s actual maximum could easily be as much as 15 or 20 beats per minute different—higher or lower—than what they get just by subtracting their age from 220.
That’s why it’s important to pay attention to cues from your body. While you need to push yourself, your body will start to tell you if you’re overdoing it.