How Hard Should I Exercise?

As a physical therapist I am constantly asking my patients about the intensity of exercises I have them perform. It’s a needed question to assure I am making a patient work hard enough, but not so hard that I am harming them.

Each time you exercise you should ask yourself, ‘Am I working as hard as I should be?’. One way to decide if you’re working hard enough is your heart rate. Some gadgets, such as Fitbits, can measure your heart rate, but you can do it yourself by feeling for the pulse in your neck or in your wrist. Each time you feel your pulse it means your heart made a beat. Your maximal heart rate is 220 – your age. As I’m 27, my maximal heart rate is 220 – 27 = 193 beats per minute. To determine your heart rate you can count the amount of beats in 15 seconds and multiply by 4; as 60s divided by 4 is 15s.

The American College on Sports Medicine recommends individuals should perform 150 minutes of moderate cardiovascular activity (ie. brisk walking, slower bicycling, water aerobics) or 75 minutes of vigorous cardiovascular activity (ie. fast walk, running, swimming laps, singles tennis) in one week. Exercises can even be done in 10 minute bouts to give you the health benefits you desire. Moderate activity is about 50-70% of your maximal heart rate and vigorous activity is about 70-85% of your maximal heart rate. So for me, maximal heart rate based on my age is 193 bpm. My heart rate during moderate activity is about 60% x 193 = 115bpm. My heart rate during vigorous activity is about 77% x 193 = 149bpm.

If you don’t want to spend time calculating your heart rate, an easy and research based way to determine how hard you’re working is the Borg Rating of Perceived Exertion Scale (see below.) There are a couple instances this scale should be used instead of your heart rate: pool activities (because the heart rate can be stunted in the pool) and when taking medications that effect heart rate. So next time you are exercising, ask yourself if you’re working as hard as you should be and remember to keep exercise fun!