Is Heart Rate a Good Indicator of Fitness?

It may not be one of the muscles you think about when you’re working out, but just as other muscles in the body become stronger the more you work them, so does the heart.

Every time you exercise, in fact, your heart muscle becomes more efficient at pumping blood through the body, eventually adapting to require fewer beats per minute to achieve the same level of output. When that happens, your resting heart rate, or how many times your heart beats per minute, lowers.

Because a lower heart rate — both at rest and during exercise — generally indicates a stronger and more efficient heart, experts often use it to measure fitness level. They also link a lower resting heart rate with lower blood pressure, a lower body weight, and a lower risk for heart disease.

Runners can use heart rate to determine how hard their bodies are working when they’re out hitting the pavement. It’s just important to keep in mind that heart rate can vary based on several factors, including:

• Age
• Genetics
• Gender
• Medication (beta blockers, for example, can slow heart rate down, while some thyroid medications can speed it up)
• Air temperature (humidity, anyone?)
• Stress or anxiety level

Numbers to know

Although heart rate monitors come pretty much standard these days with any fitness tracker on the market, there are really only a few numbers you need to determine the strength of your heart. And you can calculate them yourself.

These include resting heart rate, maximum heart rate and target heart rate. (Note that heart rate is actually a much better indicator of workout intensity than pace because it measures how hard your body is working, not simply how fast you’re going.)

RESTING HEART RATE

Your resting heart rate measures how many times your heart beats per minute (bpm) when you’re calm. The average resting heart rate is usually between 60 and 80 bpm, but athletes can have resting heart rates as low as 30 to 40 bpm.

To find your resting heart rate, simply place your finger just below the thumb on the inside of your wrist or on either side of your neck and count your pulse for 30 seconds. Then, double it to get your beats per minute.

MAXIMUM HEART RATE

Your maximum heart rate (MHR) is the rate considered the highest your heart can handle during a workout. If you train at an intensity level above your MHR, it can be dangerous (and why treadmills and other exercise machines always come with stickers warning you to stop working out if you become short of breath or dizzy).

To calculate your maximum heart rate, subtract your age from 220.

TARGET HEART RATE

Some experts and coaches recommend heart rate training, which tracks the intensity of your workout against your maximum heart rate and is expressed as a range of numbers that indicates how fast your heart should be beating during exercise.

Many athletes train between 50 and 70 percent of their MHR. As an example, someone with an MHR of 180 bpm would have a target heart rate of between 90 and 126 bpm.  

Heart rate training can help ensure you’re getting the most out of your workout but staying at a level that’s safe for you — the middle ground between not pushing hard enough and overexerting.

The takeaway

Heart rate can be a great way to train if you want to measure your intensity. It can give you a ceiling to stay beneath on easy runs, a range to shoot for during workouts, and a warning if you’re ever pushing at a dangerous level.

Also, paying attention to your resting heart rate over time can give you the satisfaction of seeing it drop — and your fitness level rise — as you put in the work, week over week.

Just don’t be disappointed if it takes a few months of consistent exercise for your resting heart rate to lower. It can take time for your heart to adapt to different intensities of stress on the cardiovascular system.

Now get out there and run your life.