Terms like rate of perceived exertion, metabolic equivalents and percentage of heart rate max may sound daunting if you’re just beginning an exercise routine. In fact, many regular exercisers don’t understand what they mean. It’s time to demystify these terms so that you can get a grip on how intense your workout is – or should be.
Guest post by Mercy Weight Management intern Scott Jamieson
As an exercise physiologist, one of the questions I frequently come across during my interactions with clients is:
How should I gauge the intensity level of my workout?
There are three key ways to monitor exercise intensity to ensure that you stay safe during exercise and get the maximum health and fitness benefits from your routine.
#1 – Rate of Perceived Exertion
A relatively simple concept to grasp when gauging intensity levels of a workout is through self-perceived exertion levels. Taken from a scale developed by Gunnar Borg, rating of perceived exertion (or RPE) is a method commonly used in the field of exercise physiology to identify intensity levels of a prescribed workout.
The scale itself is designed on a 6-20 standard with 6 indicating “no exertion at all” and 20 indicating a “maximal effort.” While it may seem odd that the scale is weighted to this degree, Borg developed it this way to coincide with particular training heart rates of healthy adults. Multiplying your Borg score by 10 will provide you with your approximate heart rate while performing a particular activity.
For example, if you are an adult under age 65 taking a brisk walk that elevates your heart rate and breathing but doesn’t make you out of breath, you would probably consider your exertion level to be “somewhat hard.” That means your workout falls in the 13 to 14 range on the Borg scale and equates to 130 – 140 beats per minute (BPM). See more examples of the Borg Scale of Perceived Exertion here.
#2 – Metabolic Equivalent
Metabolic Equivalent, or MET training, is a frequently used term to express the intensity of a given physical activity. MET is the ratio of energy you expend during an activity to the rate of energy you expend at rest. To give you a starting point, one (1) MET is considered to be the average resting energy expenditure of a healthy adult.
MET is also the basis for individual’s measured oxygen consumption during exercise. When you studied science in elementary school, you undoubtedly learned that humans inhale oxygen and exhale carbon dioxide back into the environment. As the intensity level of your workout increases, so does your oxygen consumption. One MET – or what the body uses to sustain vital functioning at a resting state – is equivalent to 3.5 mililiters of oxygen per kilogram of body weight multiplied by the number of minutes spent exercising (often abbreviated as ml/kg/min).
As with RPEs, MET levels can be divided into three distinct subgroups (light, moderate, vigorous) when gauging intensity levels. Light intensity on the MET level would be considered anything under 3 MET, such as light desk work or strolling around the neighborhood (< 2.0 mph). Moderate intensity MET levels would be considered anything from 3-6 which would include light calisthenics to commuting to work on a bicycle. Lastly, vigorous intensity exercise, which is recommended to achieve peak fitness levels, can be identified on the MET scale as anything greater than 6 METs. Examples of vigorous intensity exercise on the MET scale would include jogging, jumping rope, and circuit weight training. Learn more about METs here.
#3 – Percentage of Heart Rate Max
Another widely used approach to assess and gauge intensity levels typically during aerobic exercise is percentage of heart rate max. That might sound a bit complicated, but it’s really not.
To calculate this percentage, take your current age and subtract that value from the absolute number of 220 to get an estimate of what your maximum heart rate should be at your age. For example, if you’re 41, your maximum BPM is 179. It’s that simple.
Obviously, maximum heart rate means just that – your maximum limit. The American College of Sports Medicine currently recommends that beginners work out up to moderate intensity (only 40-50% of your heart rate maximum) and train at that specific intensity level until comfortable enough to increase workout intensity. For example, a 41-year-old beginner should aim for a target zone of 72 – 90 BPM. If you’ve lived a relatively sedentary life for a while, you might be training at the same intensity level for weeks or sometimes months, depending on your current fitness level.
Once you’re ready for the moderate level, you can aim for 50-70% of your maximum heart rate. A 41-year-old’s target zone is 90 – 125 BPM. If you’re healthy enough for vigorous training, aim for 125 – 152 BPM (70-85% of maximum heart rate).
Studies have shown that execising at 60-70% of your heart rate max can deliver considerable cardiopulmonary responses that lead to a longer life. And there’s no better reason than that for keeping track of your workout intensity!
Need some help staying focused and motivated in your workouts? Check out the four simple tips I shared in my last blog post.
Do you live in the Canton, Ohio, area and need help with losing weight, managing a chronic health condition or starting an exercise program? Mercy can help. Contact Mercy Weight Management or Mercy Health & Fitness to set up your appointment.
Mercy intern Scott Jamieson is currently finishing his master’s degree in exercise physiology at the University of Akron, where he serves as a teaching assistant for the School of Sport Science & Wellness. Scott, originally from Wilkes-Barre, Penn., obtained his undergraduate degree in exercise science in 2013 from East Stroudsburg University of Pennsylvania prior to moving Akron, Ohio, to begin his advanced education.