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workout & exercise time vs. intensity

A common question I hear is: how much time do you really need to spend exercising to lose weight or get fit, and does intensity play a role in that?


Listen to Dr. Neal address this topic on Episode 470 of the podcast Optimal Health Daily.


The American College of Sports Medicine is considered the most respected agency when it comes to exercise science in the U.S. Their definition of exercise is:

30 minutes of planned, structured moderate intensity exercise, 3 or more days per week.

Moderate intensity would be like brisk walking for most folks, or walking at about 3.5 mph. But why do we have to walk for 30 minutes? The thinking is that if we are performing exercises at a moderate intensity, then in order to make our heart and lungs healthier, we need to maintain the activity for long enough to achieve these benefits.

What happens if we increased the intensity? Do we still need to exercise for 30 minutes? Before I answer that, I need to explain a couple of things first.

When we talk about exercise, there’s this thing called the F-I-T-T-V-P (or “FITT-VP”) Principle. How perfect that when we talk about exercise science, there’s a term called the “FITT Principle,” right? We’re dorky like that.

Here’s what those letters stand for:

  • F – Frequency
  • I – Intensity
  • T – Time
  • T – Type
  • V – Volume
  • P – Progression

This acronym is the guiding principle behind getting fit and improving your overall fitness level. The way this works is that as long as you modify at least one of the letters in FITT-VP, you’re progressing.

If you happen to work out for a shorter period of time–for example, less than 30 minutes–then you have decreased the T in the FITT-VP principle. In order to make up for that, something else needs to increase. Maybe you increase the F (the frequency) of your workouts.

Even though you’re not working out for as long during each session, by increasing how often you exercise, you can still improve your fitness level. Or if it’s not possible to increase the frequency of your exercise, but you still don’t have time to squeeze in a full 30 minute workout, maybe you consider increasing the “I” (intensity). For example, instead of walking for 30 minutes, you try jogging or running. Because you’re increasing the intensity, you won’t be able to exercise as long, and that’s ok! By increasing the intensity, you’re making your heart and lungs work harder which will still help improve overall fitness.

For me, there are days when I just want to sleep in a little longer before I start my work day; I want to squeeze in those last few minutes of sleep. At the same time, I don’t want to skip exercising that day, either. I know how much better I feel when I can get a workout in before heading to work. In this case, I know the “T” in the FITT-VP principle is going to be decreased. But that’s ok, because I can change something else (the frequency, intensity, type of exercise, volume, or progression). I can change the type and the intensity of activity I do so that I can still improve my overall fitness.

There are days when I’ll complete a 7- or 8-minute workout. Even though the workout is brief, I’ve amped up the intensity so much that I will feel pretty wiped by the end. Examples are:

  • Performing 200 double-unders followed by 200 situps as fast as I can
  • Doing 100 pull-ups, 100 push-ups, 100 sit-ups, and 100 body weight squats as fast as possible
  • Run a mile as fast as I can (which should take less than 10 minutes for those without any underlying injuries or health conditions)

The great news about exercise and improving fitness is that there are many ways to approach it. The bottom line is that each exercise session does not have to last 30 minutes every single time. As long as you aim to increase at least one of the FITT-VP components, you’re making progress toward your goals.

Listen to Dr. Neal address this topic on Episode 470 of the podcast Optimal Health Daily.