3 Simple, Low-Tech Ways to Measure Exercise Intensity
Exercise intensity refers to how much energy you’re expending when you work out. In other words, how hard are you working out. Intensity can be divided into three categories: low intensity, moderate intensity, and high intensity. Why should you know how hard you’re working?
There’s a threshold intensity that you need to achieve intensity you need to improve your cardiovascular fitness. To maximize the cardiovascular benefits of a workout, you need to exercise at a moderate intensity or greater during most of your training sessions. You can also get cardiovascular benefits from short, high-intensity sessions because you’re trading duration for intensity. In fact, research shows you can get similar benefits in half the time with high-intensity interval training.
So, how do you know how hard you’re working?
Monitor Your Heart Rate
One way to measure how fast your heart is beating is to wear a heart rate monitor when you exercise. If you don’t have a heart rate monitor, you can periodically stop and place your finger against the carotid artery in your neck and count the number of heartbeats you feel for ten seconds. Then, multiply by six to get your heart rate.
To determine exercise intensity using your measured heart rate, you must also know your maximum heart rate. There’s a standard formula for this, and you can also find maximum heart rate charts online that give you these values at a glance based on your age. The formula has recently been upgraded to make it more accurate:
Maximum Heart Rate Formula
206.9 – (0.67 x age)
To use the formula, plug your age into the equation to get your maximum heart rate. Once you know your maximum heart rate, compare the heart rate you measure during exercise to that value.
If your measured heart rate is 40% to 50% of your maximum heart rate, you’re working out at a low intensity. Exercise should feel comfortable at this level even for long periods of time. If your measured heart rate is 51% to 70%, you’re working out at a moderate intensity. This is an intensity range that people strive for when doing long distance cycling or running. It’s in this range that you start to get full cardiovascular benefits, as long as you maintain exercise for 20 minutes or longer.
Beyond 70% of your maximum heart rate and you’re in the high-intensity zone. When you hit 80% to 90% of your maximum heart rate, it’s difficult to exercise at that intensity for long. People who do high-intensity interval training work out at this intensity during the active intervals.
Keep in mind that calculated maximum heart rate using the above formula is an approximation. The only way to determine it with absolute accuracy is to hop on a treadmill while technicians monitor your heart rate.
The Talk Test
Heart rate isn’t the only way to determine how hard you’re working. You can also use the “talk test.” It’s a pretty straightforward approach and is scientifically validated by a study carried out at the University of Wisconsin at Lacrosse. It’s based on the concept of the ventilatory threshold.
When you exercise beyond a certain intensity, you exceed the ventilatory threshold of your lungs. This is the point when breathing becomes labored. You’ve probably experienced it during a past high-intensity workout. You’re exercising at an intensity where you can’t say a complete sentence because you’re working so hard to breathe. It’s hard to get out a complete sentence because you’re above your ventilatory threshold and are in the anaerobic zone.
Here’s how the talk test works.
If you’re exercising at an intensity that it’s hard to talk in complete sentences, you’re at or above your ventilatory threshold and are working out at a high intensity. You may be able to get out a word or two, but you can’t string those words together to form complete sentences.
If you can get out a complete sentence, yet it’s difficult to carry on a conversation, you’re just below your ventilatory threshold and are in the moderate intensity zone. But if you can recite a poem or sing a song, you’re working out at a low intensity. Exercise feels comfortable at this level.
Rate of Perceived Exertion
Another low-tech way to estimate how intensely you’re exercising is to use the perceived exertion scale. With this scale, you rate how hard you’re exercising on a scale of one to ten with one being the easiest and ten the hardest. One on the perceived exertion scale would correspond to a relaxed state. You’re chilling! However, a ten would be sprinting as fast as you can to escape from a bear that’s hot on your trail.
If you rated your exercise intensity between three and five on the perceived exertion scale, you’re exercising at a low intensity. If it’s between five and seven, you’re working out at a moderate intensity. Beyond seven, you’re in the high-intensity zone. Although this is a subjective assessment, research suggests people are fairly accurate at estimating exercise intensity using this scale.
You really don’t need a fitness tracker or even a heart rate monitor to estimate exercise intensity. The talk teste and perceived exertion scale is a handy way to track how hard you’re working. Don’t exercise at the same intensity each time you train. If you train in the high-intensity zone all the time, you’ll accumulate fatigue and quickly burn out.
After a high intensity one day, give yourself a day of rest or work out at a low intensity to give your body time to recover. You’re in this for the long haul, and you don’t want to end up over-trained and exhausted. Now, you have a better idea of how to monitor exercise intensity, and you can do it without fancy equipment or gadgets.
ACE Fitness. “Validating the Talk Test as a Measure of Exercise Intensity”
Med Sci Sports Exerc. 2007 May;39(5):822-9.
IDEA Personal Trainer. 14(1) 36-42.