What is Exercise Intensity and How Do I Measure It?

Exercise intensity can be measured in a few different ways. Learn the benefits of gauging your intensity while you're working out, and how WHOOP helps you stay on track.

What is Exercise Intensity?

Exercise intensity is the amount of energy you expend during physical activity. It determines the benefits you’ll receive from a specific workout, such as increased strength, weight loss, metabolic burn, and cardiovascular fitness. There are three zones of exercise intensity: Low, Moderate, and Vigorous. The U.S. Department of Health and Human Services recommends 75 minutes of vigorous activity in a week or 150 minutes of moderate intensity exercise. Below we’ll discuss how to measure exercise intensity, the benefits of each zone, and activities that hit each intensity.  

Measuring Your Exercise Intensity

There are three common ways to check your exercise intensity. The talk test, measuring your heart rate, and the Borg Perceived Exertion Scale. The Talk Test is the easiest way to figure out your exercise intensity. You should be able to hold a conversation during a low-intensity workout, but as intensity increases speaking becomes more difficult. During a vigorous workout you won’t be able to say more than a few words without pausing for a breath. Target Heart Rate: Measuring your heart rate is another way to monitor your energy expenditure during exercise. To do that, you need to determine your max heart rate and calculate your target heart rate for each activity. Start by finding your resting heart rate. WHOOP measures your resting heart rate each night. You can also figure it out by taking your pulse when you first wake up.

1. Subtract your resting heart rate from your maximum heart rate.
2. Multiply that number by your percentage of training intensity. Then, add your resting heart rate to get your target heart rate.

For example, a 40-year-old woman with a resting heart rate of 65 and a max HR of 180 who wants to exercise at 70% intensity the formula looks like this:

1. 180 - 65 = 115
2. (115 x 70%) + 65 =145.5 (target heart rate)

Use this chart to target your heart rate zone to optimize your workouts.

READ MORE: Guide to Heart Rate Zone Training Borg Rating of Perceived Exertion Scale: The Borg RPE Scale was introduced by Swedish professor Gunnar Borg in 1982 after years of researching the concept. The Borg RPE Scale asks you to rate your level of perceived exertion during any activity from 6-20, with 6 being no effort at all and 20 being your all-out max. Borg developed the RPE scale to represent an estimate of what your heart rate is when you multiply the number by 10. For example, if you go for a light jog and rate your exertion a 13, your heart rate is likely in the neighborhood of 130 beats per minute (bpm). Similarly, an anaerobic workout such as spin class might feel like a 17, with a heart rate around 170 bpm.  

Choosing Your Exercise Intensity

Understanding exercise intensity will give you a better feel for how hard you’re working when doing any activity. Low intensity exercises can be done for longer periods while vigorous intensity work should only be done in short bursts, like a sprint. Exercise intensity helps you gauge your effort and maintain a safe level of exertion. Low Intensity Activities Low-intensity exercises are light activities that build endurance, burn fat, and are sustainable for prolonged periods. This is a good intensity for warming up and cooling down. Your heart rate will be lower than 50% of your maximum heart rate. You will breathe normally, be able to hold a conversation, and you probably won’t sweat. You’ll feel somewhere between 6 and 11 on the Borg RPE Scale. Workouts include:

• Walking slowly
• Slow speed on elliptical machine
• Cycling at a casual pace

Moderate Intensity Activities Your breath quickens while you’re doing moderate intensity actions, but you don’t feel out of breath. You may still be able to speak but carrying on a conversation is difficult. You’ll also develop a light sweat after about 10 minutes and your heart rate is generally between 50 and 70% of your max HR. It should be between 12 and 15 on the Borg Scale. Workouts include:

• Walking 2 miles in 30 minutes
• 30 minutes of water aerobics
• Swimming laps for 20 minutes
• Gardening for 30-45 minutes
• Light weight lifting
• Cycling 5 miles in 30 minutes
• Jumping rope for 15 minutes
• Climbing stairs
• Playing basketball

Vigorous Intensity Activities Vigorous intensity workouts feel challenging, and you won’t be able to say more than a word or two at a time. Your heart rate increases into the aerobic and anaerobic zones, between 70 and 85% of your max HR. Your breathing is deep and rapid, and you develop a sweat after only a few minutes. You’ll reach in the neighborhood of 16-20 on the Borg Scale. Workouts include:

• Speed walking
• Running
• Swimming laps
• Tennis (singles)
• Aerobics
• Spin class
• Hiking or rucking
• Heavy gardening and yard work
• Heavy weight lifting
• High intensity interval training (HIIT)

You’ll get the most out of your workouts by maintaining the proper exercise intensity. Pushing yourself too hard can result in injuries, pain, and poor results. Mixing up intensities in your workout can give you a breather and make your workout more interesting.  

Maximize Your Workout with WHOOP

WHOOP uses a proprietary algorithm inspired by the Borg Scale to quantify the strain your body takes on during a workout. Using the Strain Coach you’ll be able to know in real-time whether you need to push harder, if you’ve reached your strain goal, or if you’re overdoing it. After your workout, WHOOP Strain quantifies your hard work so you can easily compare one activity to the next.