Target Heart Rate: Are You Working Out Hard Enough?

As if getting motivated to work out isn’t difficult enough, there’s also the question of whether or not you’re working out hard enough. This is generally described in terms of “intensity”. While you can achieve significant health benefits with as little as 30 minutes of low-intensity exercise (walking, leisure swimming or gardening),  I must emphasize that moderate-to-high-intensity forms of exercise (bicycling, lap swimming or running) tend to result in greater improvements in cardiovascular function and overall fitness.

Similarly, if your workout goals are centered on weight loss, mixing low-to-moderate-intensity exercise with short bursts of high-intensity exercise (high-intensity interval training/HIIT) can greatly enhance fat burning potential and weight loss over time.

So, how do you know if your workouts are intense enough? Monitoring your heart rate (the number of heart beats per minute) is one of the best ways to measure your intensity level.

Related Article: How to Perform Cardio Exercise the Right Way

Measuring Your Workout Intensity

Depending on your desired workout intensity, your heart rate should be within a certain target range. Many cardio machines (treadmills, stair climbers, ellipticals, and stationary bikes) allow you to electronically monitor your heart rate during exercise. Problem is, the recommended target heart rate zone depicted on most machines may not be right for you, as it’s based solely on a general equation known as the age-predicted maximum heart rate.

Age-Predicted Maximum Heart Rate

220 – Age = Maximum Heart Rate (MHR)

Depending on what goal(s) you’re trying to accomplish, your target heart rate zone is determined as a percentage range of your maximum heart rate as shown below.

Target Heart Rate Zone

Low-Intensity Exercise/General Health

55-65% of MHR

Moderate-Intensity Exercise/Fitness/Fat Burning

65-85% of MHR

High-Intensity Exercise/Cardiovascular Endurance

Above 85% of MHR

The following example uses a 25-year-old woman who’s trying to get fit by working out at a moderate-intensity level.

Age-Predicted Maximum Heart Rate

220 – Age = MHR

220 – 25 = 195

Target Heart Rate Zone

MHR x 0.65 = (low target)          MHR x 0.85 = (high target)

195 x 0.65 = 127                       195 x 0.85 = 166

As you can see, this 25-year-old woman would have to work out at an intensity that’s high enough to spike her heart rate somewhere between 127 and 166 beats per minute.

Unfortunately, when the maximum heart rate is used to determine the target heart rate zone individual differences are not taken into account. This essentially means that a woman (or man) of the same age would have the exact same heart rate zone regardless of other relevant factors such as body weight, stature, fitness level, etc.

So, how can you determine what target heart rate zone is right for you? Well, lucky enough, there’s a simple solution.

The resting heart rate is actually a great marker of cardiovascular function and general fitness. In fact, during routine office visits medical professionals usually take a resting heart rate by placing two fingers on your radial pulse (located on the wrist) or by way of a pulse oximeter in order to get a quick marker of your health status.

An adult who’s pretty healthy would generally have a resting heart rate between 60 and 80 beats per minute while a well-trained athlete may have a resting heart rate as low as 30-40 beats per minute. A relatively low heart rate at rest is generally indicative of enhanced fitness due to a more efficient cardiovascular system.

Related Article: The Seven Principles of Exercise

Now, obviously with such a large range of possibilities for the resting heart rate, recommended target heart rate zones depicted on cardio machines simply can’t account for endless variations between different people. While the heart rate reading itself is okay, the best way to know what heart rate zone works best for you is to factor in your own resting heart rate.

Determining Your Resting Heart Rate & Target Heart Rate Zone

Resting heart rate is best determined in the morning after a good night’s rest. Before taking the measurement, allow your body a few minutes to adjust to the natural shift from sleeping to waking up. When you’re ready to measure your resting heart rate, take your index and middle fingers together on the opposite wrist about 1/2-inch on the inside of the joint, in line with the index finger. Once you feel a pulse, count the number of beats you feel for one minute.

After you’ve determined your resting heart rate you can use what’s called the heart rate reserve (the difference between your predicted maximum heart rate and resting heart rate) to determine your target heart rate zone. Here’s how you can do this using the moderate-intensity heart rate zone from above:

Age-Predicted Maximum Heart Rate

220 – Age = MHR

Heart Rate Reserve

MHR – Resting Heart Rate (RHR) = Heart Rate Reserve (HHR)

Target Heart Rate Zone

RHR + (HRR x 0.65) = (low target)          RHR + (HRR x 0.85) = (high target)

Using the same 25-year-old woman from before, let’s factor a resting heart rate value of 65 beats per minute into the equation:

Age-Predicted Maximum Heart Rate

220 – Age = MHR

220 – 25 = 195

Heart Rate Reserve


195 – 65 = 130

Target Heart Rate Zone

RHR + (HRR x 0.65) = (low target)          RHR + (HRR x 0.85) = (high target)

65 + (130 x 0.65) = 150                         65 + (130 x 0.85) = 176

So, now she’d have to work out at an intensity that’s high enough to spike her heart rate somewhere between 150 and 176 beats per minute in order to significantly improve her fitness level. This is a large variation from before. Also, notice that as resting heart rate decreases, the heart rate reserve increases. This is indicative of improved cardiovascular function and overall fitness.

The Net-Net

All things considered, if you’re really trying to get fit, the amount of work you perform during any exercise session must be intense enough. For real results, you’ll have to put in some real effort. Unfortunately, the exercise intensity-related information depicted on most cardio machines can be quite misleading, as it does not factor in individual qualities like your health status as measured by resting heart rate.

Although the calculation requires a little extra time and effort on your part, the heart rate reserve method is best for reaching an optimal workout intensity based on your target heart rate.

Learn more about intensity and other fundamental exercise training principles. Get your copy of Leaving Your Fat Behind today!

Disclaimer: The information provided is for educational and informational purposes only and is not intended to diagnose, treat, cure or prevent any disease. Any reader who is concerned about his or her health should contact a physician for advice.

Before starting an exercise training program you should first make sure that exercise is safe for you.  If you are under the age of 55 years and generally in good health, it is probably safe for you to exercise.  However, if you are over 55 years of age and/or have any health problems, be sure to consult with your physician before starting an exercise training program.