On Exercise Intensity: How hard (or easy) should I workout?

141_1Exercise Intensity – or how hard or easy your body is working – is often misunderstood or neglected, but it is an essential aspect of exercise because this determines whether you are burning enough calories and challenging your body to reach your goal, or you are just wasting your time in the gym! You want to get the most out of your workouts, but you also wouldn’t want to burn yourself out and get injured by working too hard.  Knowing the right intensity for your workouts will help you train effectively and maximize your time in the gym.

So how do you know if you’re working hard enough or too much? I’ll teach you three ways to measure exercise intensity:


The Target Heart Rate

First is through knowing your Target Heart Rate (THR). To reach your goals, you should exercise at a specific intensity based on your THR without going overboard and push your body too much! Now because you have a ‘target’ there is also a base heart rate known as the Resting Heart Rate (RHR). This how fast your pulse is while at rest and you’re not doing anything. According to the National Institute of Health, the average RHR for 10 years old and up is 60 to 100 bpm. Elite athletes could have an RHR as low as 40 bpm!

Follow these steps to know your heart rate during exercise:

  • Sit down and put your left hand on your lap, palm facing up.
  • Use the tips of your index and middle finger of your right hand to get your pulse by placing them together on top of your left wrist on the thumb side.
  • With a timer, count your pulse for 20 seconds and multiply it by 3 to find the bpm.
  • Compare your result to the table below:
Age Target Heart Rate Zone (50-85%) Average Maximum HR
20 100-170 bpm 200 bpm
30 95-162 bpm 190 bpm
35 93-157 bpm 185 bpm
40 90-153 bpm 180 bpm
45 88-149 bpm 175 bpm
50 85-145 bpm 170 bpm
55 83-140 bpm 165 bpm
60 80-136 bpm 160 bpm
65 78-132 bpm 155 bpm
70 75-128 bpm 150 bpm

This table only shows an estimated THR for different age ranges. Your Maximum Heart Rate (MHR) is 220 minus your age as a standard. The Maximum Heart Rate, as the name implies, is the maximum amount of beats that your heart can make in a minute. When you’re doing strength training at a moderately intense level, your heart rate should be about 50-69% of your MHR. When you’re working at a heavy intensity, your THR should be 70-89% of your MHR. During rest periods, your heart rate will definitely start going lower the moment you stop lifting weights – and this is what rest periods are exactly for: for your muscles and your heart to recover.

If you’re just starting to exercise, aim for the lower range of your THR zone (around 50%) during the first couple weeks of working out. Gradually build up to the higher range (up to 85%) and as you progress you will be able to exercise comfortably at that THR zone.

If you have been exercising for a while now, it’s time to evaluate your exercise intensity. Are you working hard enough? Or you may have been working out too hard every time and this will lead to fatigue. You can also “reset” your program and start at a lower range. You can build up faster to your Target Heart Rate, but now you will be more aware of your heart rate and the exercise intensity.


The Borg Scale

Now, you probably think ‘I can’t always check my heart rate every time I do a set!’ and you’re right! It is objective but not always practical (unless you get a heart rate monitor), and this is why a guy named Dr. Gunnar Borg devised a simpler and more accessible way to measure exercise intensity. This is called the “Borg Scale” (obviously named after him) also called as the Rate of Perceived Exertion or RPE. It is a subjective scale that measures how you “feel” while exercising with numbers from 6 to 20.

The scale starts at 6 which is equivalent to “no exertion” and ends at 20 which equates to “very, very hard.” Physical activities at moderate intensity register 11 to 14 on the Borg scale (“fairly light” to “somewhat hard”), while vigorous intensity rates from 15 to 20 (“hard” to “very, very hard”). Dr. Borg set the scale from 6 to 20 to make it a simple way to estimate heart rate. See the table below:

Exertion Level Borg Rating Examples of Physical Activities
None 6 Reading a book, watching television
Very, very light 7 to 8 Writing, Tying shoes
Very light 9 to 10 Chores like folding clothes, washing dishes, that seem to take little effort

Fairly light


11 to 12

Walking through the grocery store or other activities that require some effort but not enough to speed up your breathing

Somewhat hard


13 to 14

Brisk walking or other activities that require moderate effort and speed your heart rate and breathing but don’t make you out of breath



15 to 16

Bicycling, swimming, or other activities that take vigorous effort and get the heart pounding and make breathing very fast
Very hard 17 to 18 The highest level of activity you can sustain
Very, very hard 19 to 20 A finishing kick in a race or other burst of activity that you can’t maintain for long

You don’t have to remember the specifics of the scale. You just have to know that when you work out, a warm-up or light exercise should be around 11 to 12 out of 20, and a near-maximal effort should be at 17 to 18 out of 20. Check yourself every now and then and estimate the intensity you’re at.


The Talk Test

The “Talk Test” is the simplest and easiest way to measure your exercise intensity.  This technique is based on your ability to talk (or not talk) while working out. When your effort is at light to moderate intensity, you can talk, but not sing during exercise. If your effort is at hard or heavy intensity you will not be able to say more than a few words without pausing for a breath.

Compare walking, jogging, and sprinting:

When walking, you can easily hold a conversation with someone and even sing a tune. Your effort is very light and the does not affect your breathing.

When you’re out jogging, you can say a few words if someone suddenly asked you for direction or you want to say ‘hi’ to a neighbor. Your effort is at moderate intensity because the activity raises your heart rate and is a little bit demanding on your breathing.

While sprinting or running fast, all you can do is to hear your legs scream and breathe deep and fast! This is high intensity when the effort requires your heart and lungs to work harder that you are not able to do other tasks.



To increase your cardiovascular endurance or stamina, you have to challenge your muscles, heart and lungs enough for them to adapt. When weight training, your heart rate does not go up as fast so you have to watch your rest periods in between sets. After you finish your reps, don’t talk too much to your gym bro or stare at your phone for a long time – do the next set whenever you feel ready so you still get the benefit of exercise intensity.

Be careful when you always exercise at a high intensity level. If you don’t give your heart some time to recover, you may be straining and overworking yourself.  Your body can’t sustain this heart rate for a long time and it will eventually lead to fatigue. If you have always been overworking at the gym or on your runs or whatever exercise you’re doing, you are just getting your body to over-fatigue and the effect of your workouts will be negative in total. So slow down.

When you go to the gym and you say hi and talk with every person you know, you might be exercising at a too low intensity. To be frank, you will be wasting your time in the gym if you are not reaching your Target Heart Rate and you’re not exerting enough effort. Whatever goal you have, whether to lose fat or build muscle or be fit, you won’t reach them this way! You will not gain any significant adaptations in your heart, lungs, and muscle if you are always exercising at a low intensity. Sweat it out. Push yourself a little harder. Run a little faster.  Start light but gradually increase the intensity and challenge yourself every time.


Being aware of how hard your body works can help you adjust the intensity of your exercise by speeding up, slowing down, changing the weights you are lifting, or simply reducing the rest intervals. When you know how your body feels, it will be easier for you to reach your desired intensity and stay on track to reach your goals!

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