10/08/2012 08:25 am ET Updated Dec 06, 2017

Exercise Intensity: How Should You Measure It?

By Kristine Lockwood

When it comes to exercise intensity, there's no "one size fits all" prescription. Some people won't break a sweat during a 5K run, while others perspire after just a couple strides. Either way, hitting higher intensities while exercising (through High Intensity Training, including many interval training protocols) has all sorts of health benefits from improving metabolism and creating lean muscle, to improving overall fitness in less time. But how do we know if we're really pushing ourselves?

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Ticker Time -- The Need-To-Know
Heart-rate training (which can be done in a variety of ways) can determine if aerobic activity is too light, too hard, or just right (just like Goldilocks). The goal is to push the heart towards its maximum ability without overworking it. Thankfully, we don't have to sprint until our chest pops to find that point.

Maximum Heart Rate Method
The Center for Disease Control and Prevention (CDC) has broken down ideal heart rates for moderate and vigorous physical activity based on age. Subtracting your current age from 220 will yield the maximum age-related heart rate. (For example, a 28-year-old has a max of 192.) The CDC counts moderate intensity as 50 to 70 percent of the max, while vigorous instensity counts as 70 to 85 percent. These percentages can be further broken down, says Greatist expert Matthew Miller. Cardiovascular exercise can be broken into four zones with 60 to 70 percent as "recovery," or light exertion, 70 to 80 percent for aerobic exercise, 80 to 90 percent for anaerobic exercise, and 90 to 100 percent for red line (read: chest popping).

Sound like a high bar to hit? These maximums are just recommended averages. It's often better to find your resting heart rate (heart beats per minute, or "bpm") and adjust from there. To find heart rate, place the index and middle finger over the carotid (neck) or radial (wrist) artery and count the pulse for six seconds. Multiply that number by 10 to get the base bpm.

Apps and Gadgets
For the techies among us, there's always a gadget or app for that, such as the Instant Heart Rate app from Azuimo, or a handy dandy heart rate monitor, which read and display heart rate just by touching the skin.

The Talking Method
Exercise intensity can also be measured with vocal (rather than circulatory) cues. One study had healthy, moderately active people exercise while attached to monitors measuring heart rate and intensity. Then they were asked to perform a "talk test" by reciting the Pledge of Allegiance at specific points in the exercise. At "moderate" intensity, the subjects were able to speak at a comfortable rate. Any increase in intensity from this point made speaking more difficult. The researchers found fluctuations in exercise intensity matched up with both the talk test and the heart rate monitor readings.

But talkers take note -- while this test is simple and effective, the chatter may need to change depending on fitness level or goals. While the talk test is a good measure of exercise intensity for casual gym-goers, it may not be effective for elite athletes. For people with advanced fitness goals (like, say, those going for a third Olympic medal), being able to carry on a casual conversation may mean exercise is not intense enough. Most novice athletes will have trouble carrying conversation at about 80 percent of their age-predicted max heart rate, says Miller.

Look Who's Talking Now -- Your Action Plan
The talk test works because talking comfortably means breath frequency, which is related to heart rate, is under control. Even though the talk test is subjective, being able to talk comfortably and therefore breathe comfortably indicates low-to-moderate intensity. Exercise recommendations from the American College of Sports Medicine suggest aiming for 30 minutes per day of simple, moderate-intensity exercise is a good way to improve general health. If the words don't flow as easily (where a breath is required after every word), the workout crosses over into the vigorous range.

Hitting the target heart rate is important to any aerobic activity, and with the talk test there's no need to revisit seventh grade math (hey, calculating heart rate can be tricky!) and no need to spend any money. All it requires are vocal cords and the ability to talk, talk, talk by reciting a few verses from a favorite rhyme, saying, or song. Choose timed intervals throughout the exercise and start talking, paying attention to how easily the words come out. The best part is there are no failing grades with this test!

How do you measure exercise intensity in your own workouts? Let us know in the comments below.

Need some motivation to get moving? Check out these inspiring fitness quotes.

Fitness Quotes

This article has been read and approved by Greatist experts Matthew Miller and Matt McGory.

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