You can, to some extent, measure your workouts by your sweat. Sweat a lot and you've really worked. Sweat a little, and well, blame it on that late-nighter you pulled in the office the other night.

Although sweat indicates when your body is working to cool itself, it doesn't always tell you how hard you've worked. For that, you need to turn to three common ways of checking your intensity: the talk test, rating of perceived exertion (RPE), and target heart rate (THR).

The Importance of Intensity

Intensity is simply a measure of how hard—or easy—you're working. Monitoring intensity when you exercise is important for many reasons, says Ken Alan, spokesperson for the American Council on Exercise (ACE) and an international fitness expert.

First, it lets you know if you're working too hard or not hard enough. Working too hard can cause overtraining which can lead to injuries, illness, decline in fitness performance, mood changes, lack of sleep, and other symptoms. If you're not working hard enough, on the other hand, it may take you longer to meet your fitness goals.

"Checking your intensity can also help you avoid working at a level that might be hazardous to your health," Alan says. In other words, if you're recovering from an injury or illness , intensity is a good way to ensure that you're not overdoing it.

Intensity can also be a crucial factor in helping you achieve goals related to sports performance. "Intensity is critical for improvements in aerobic capacity and sports performance," Alan says. For example, if you're training for a faster time in a 10K run, you'll need to vary the intensity of your workouts, some days working harder than others.

Testing Your Intensity


The Talk Test

This is the easiest test to administer, especially if you're new to exercise. The premise of the talk test is simple: no matter how hard you're exercising, you should still be able to talk.

This doesn't mean that you have to be able to carry on a whole conversation. Instead, you should be able to speak in broken sentences. If you're too winded to talk and have to gasp for breath between words, you're working too hard. If you feel as if you could talk for hours, you may not be working hard enough.

Rating of Perceived Exertion (RPE)

Another easy way to find out how hard you're exercising is by using RPE which measures how you feel and how hard you think you're working. Of course, this requires that you be honest with yourself.

RPE lets you rate your exertion on a scale that runs from 0 to 10. Here's how the scale looks, according to the American Council on Exercise (ACE):

For the general population, ACE recommends working between a 3 and a 5. Of course, the toughest part with this intensity check is translating how you're feeling into a number on the scale.

Lying in bed, for example, which obviously uses little exertion, would rate a 0. Let's say, though, that you're running at full speed to catch a bus that's pulling away from the curb. By the time you catch the bus, your heart is pounding and sweat is rolling down your forehead. Your exertion would undoubtedly rate a 10.

Target Heart Rate (THR)

Perhaps the most popular method of measuring intensity is THR. According to ACE, THR is "the number of heartbeats per minute that indicate appropriate exercise intensity levels for each person."

Most experts recommend that people in good health work between 50% and 80% of their maximal heart rate—the highest heart rate you can achieve. (Please note that if you're taking medication, your range may be lower; talk with your doctor to find out your recommended heart rates.)

Finding Your Target Heart Rate

To find your estimated maximal heart rate, subtract your age from 220. For example, if you are 30, your maximal heart rate is 190 beats per minute (bpm). To find your target heart rates, do as follows. Multiply your maximal heart rate by 50% and you come up with 95 bpm. Multiply 190 by 80% and you get 152 bpm. This means that after you've warmed up, you should try to keep your heart rate between 95 and 152 bpm, staying toward the lower end if you're just beginning an exercise program.

Calculating Your Heart Rate

To find your heart rate, you can use a heart rate monitor. But if you don't feel like sinking $60 or more into a monitor, you can easily calculate your heart rate using palpation.



Radial pulse —Place your fingers over the radial artery in your wrist. You'll find it where the base of your thumb connects to the palm side of your wrist.


Once you've found your pulse, count the number of beats for 10 seconds. Try to do this within 10 seconds after you've stopped exercising. While you're doing this, move around so that you don't get lightheaded or dizzy.

Take your 10-second heart rate and multiply it by six. What you've just found is the number of times your heart is beating per minute. For example, if your 10-second count is 18, then your heart rate is 108 bpm—inside your target range if you are 30.

Remember, though, that THR is just an estimate. Heart rates can often be affected by stress, medications, fatigue, caffeine, and other factors. Also, if you're exercising in water, your heart rate may be lower depending on the water temperature.

Intensity Basics

Now that you know how to monitor your intensity, how often should you check it? If you're new to exercise, monitor your intensity frequently during an exercise session, possibly every 10 minutes.

"When you first start a cardiovascular program, monitoring your intensity is important in helping you achieve improvements in your aerobic fitness level," Alan says. It will also ensure that the level at which you're working is safe for your age, fitness level, and medical status. Once you're familiar with how your body responds to exercise, though, you can monitor your intensity less often.