Fitness Intensity: How to Tell How Hard You’re Working for Your Goals

(U.S. Marine Corps/Cpl. Todd F. Michalek)

Fitness intensity can be one of the most subjective areas of working out. From “rate of perceived exertion” (or RPE) to the famous “runner’s high” or getting “in the zone,” these metrics can, at best, give a ballpark estimate at the level of effort we employ during our workouts. But while how you feel during a workout is important, there is a more objective way to grade your effort.

Like all things scientific, “Training Zones” begin with measurement, using heart rates and recovery times as grading criteria for the level of effort you are using as well as the level of fitness you are improving. Starting from easiest to hardest, this is the typical intensity measurement we use for an understanding of our effort levels.

Rate of Perceived Exertion Levels

Very light activity. Examples include walking in the park, sitting on a stationary bike, gently pedaling and stretching. This activity level is just a little harder than sleeping, but it is moving, and for many who do not move, this is a great place to start. Think of rest and digest-level activity that will stimulate the parasympathetic nervous system.

RPE 2 to 3
Light activity. A brisk walk at a conversational pace is a great example of this level of effort. This is something you could do for hours if you had to, but a great way to burn calories and de-stress. Depending on your conditioning, this is also rest and digest mode. An easy walk after dinner has excellent health benefits.

RPE 4-6
Moderate Activity. This effort is not so much conversational pace as it requires heavier breathing and focused breathing cycles (with full inhales and quick full exhales). Toward the end of a warmup, picking up the pace to get the heart rate going is about the activity level. If you can run a six to seven-minute mile but choose to run an eight-minute mile, this may be a comparison, depending on your current ability.

RPE 7-8
Vigorous Activity. Maxing out a 1.5-mile timed run at a six-minute mile pace will make you short of breath, uncomfortable and barely able to speak a full sentence. You may need a minute to recover the ability to be conversational again.

Very hard activity. Near full speed and difficult to maintain the pace or exercise intensity. These are faster runs, heavier lifts and maximum rep calisthenics events that hurt and make it unable to communicate verbally. Think of sprinting with whatever you have left on the last lap of a 1.5-mile timed run. This is part of the power and speed training zone.

RPE 10
Maximum effort activity. These are a full sprint, max one-rep max lifts and near failure on calisthenics sets. Giving it all you have will only last seconds but, this is the power and speed training zone and requires maximum effort.

Training Zones: Objective Assessment Using Heart Rate

A more objective assessment of your training intensity is to gauge your heart rate during workouts to see how your conditioning is improving and how hard you are pushing yourself. With your heart rate in mind, you can adjust your workouts to work in different training zones.

In fact, as a tactical athlete serving in the military, police and firefighting professions, you need to address all of the following zones in your training, as you never know what your job will require you to do. In life-or-death situations, having a solid grasp on performing in these zones will make a difference.

Zone 1
The easy zone that keeps the heart rate to 50-65% of your max heart rate. If your max heart rate is 190 beats per minute (BPM). A ballpark way to determine your max heart rate is using the 220-age formula. So, if you are 30 years old, your theoretical max heart rate is 190 bpm. Keeping your heart rate under 100 bpm is easy walking, biking, and stretching. Think cooldown and recovery zone. Here are some zone 1 ideas for moving more.

Zone 2
This is the aerobic base training for endurance. It's not super easy, but it's not difficult either. Similar to the RPE scale above, this is a conversational pace. Depending on your conditioning, this could be a brisk walk or a seven-minute mile run (if you are in great running shape and can do a sub-five-minute mile).

Many will use a long, slow, distance run as an aerobic base builder in this zone, but you can also do it with biking, swimming, rowing or other activities as long as you keep your heart rate at 65-75% of your max heart rate. Ideas for zone 2 training.

Zone 3
This is a medium-intensity effort similar to tempo run training. This zone is not sprinting, but it is working to maintain a set fairly difficult pace for 20-30 minutes (or longer, depending on conditioning). This zone requires a zone of 75-85% max heart rate.

Zone 4
This is near maximum effort at 85-90% of your max heart rate. These are usually short bouts of effort such as sprinting, max repetition sets of calisthenics and just under maximum weight lifted.

Zone 5
This zone is as hard as possible in sprinting, burn-out sets of calisthenics, and maximum effort weights lifted. Zones 4 and 5 are usually measured in seconds, while recovery periods are measured in minutes. This effort level will produce 90% or higher in your max heart rate. This is our anaerobic zone associated with maximum intensity and feeling like you will throw up after this max-intensity moment.

Select how you wish to assess your effort levels. I have found that combining both methods above is an excellent method, and you can tie the RPE levels to the zones accordingly but with more accuracy. Getting good at everything in tactical fitness makes you fit for service. Ensure your programming involves strength, power, speed, agility, grip training, endurance in multiple modalities, muscle stamina, flexibility and mobility to be a well-rounded tactical athlete.

Stew Smith is a former Navy SEAL and fitness author certified as a Strength and Conditioning Specialist (CSCS) with the National Strength and Conditioning Association. Visit his Fitness eBook store if you’re looking to start a workout program to create a healthy lifestyle. Send your fitness questions to

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