The F.I.T.T. Principle for Great Workouts

Man and woman stretching at the gym
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When it comes to fitness and exercise, there's one very important guiding principle that helps us figure out the best way to set up a workout program.

The F.I.T.T. principle is the foundation of exercise, a set of guidelines that cover all the elements you need to think about to create workouts that fit your goals and fitness level, as well as helping you get the most out of your exercise time.

F.I.T.T. stands for frequency, intensity, time, and type of exercise.

Here's how the F.I.T.T. principle works.

Frequency

The first part of your workout has to do with how often you exercise. Your frequency often depends on a variety of factors including the type of workout you're doing, how hard you're working, your fitness level, and your exercise goals.

In general, the exercise guidelines set out by the American College of Sports Medicine give you a place to start when figuring out how often to workout.

  • For cardio: Depending on your goal, guidelines recommend moderate exercise five or more days a week or intense cardio three days a week to improve your health. If you want to lose weight, you'll want to work up to more frequent workouts, often up to six or more days a week.
  • For strength training: The recommended frequency here is 2-3 non-consecutive days a week (at least 1-2 days between sessions). Your frequency, however, will often depend on the workouts you're doing, because you want to work your muscles at least 2 times a week. If you do a split routine, like upper body one day and lower body the next, your workouts will be more frequent than total body workouts. 

    Intensity

    The next part of your workout has to do with how hard you work during exercise. Again, this will differ depending on the workout you're doing. 

    • For cardio: For cardio, we usually monitor intensity by heart rate, perceived exertion, the Talk Test, a heart rate monitor or a combination of them. The general recommendation is to work at a moderate intensity for steady state workouts. But, if you're doing something like interval training, which is recommended about once or twice a week, you'll work at a high intensity for a shorter period of time. It's a good idea to have a mixture of low, medium, and high intensity cardio, so you stimulate different energy systems and avoid overtraining.
    • For strength training: Monitoring the intensity of strength training involves a different set of parameters. Your intensity is made up of the exercises you do, the amount of weight you lift and the number of reps and sets you do. The intensity can change based on how you're training. The general idea is to lift enough weight so that you can only complete the number of reps you've chosen. However, if your goal is to lose weight or build endurance, you might lift lighter weights for more reps.

    Time 

    The next element of your workout is how long you workout. There isn't one set rule for how long you exercise and it will typically depend on your fitness level and, of course, the type of workout you're doing.

    • For cardio: The exercise guidelines suggest 30 to 60 minutes of cardio but, of course, the duration of your workout depends on what you're doing. If you're a beginner, you might start with a 15- to 20-minute workout. If you're doing steady state cardio, say going for a run or getting on a cardio machine, you might workout for 30 to 60 minutes. If you're doing interval training and working at a very high intensity, your workout will be shorter, around 20 to 30 minutes. Having a variety of workouts at different intensities and durations will give you a solid, balanced cardio program.
    • For strength training: How long you lift weights depends on the type of workout you're doing and your schedule. For example, a total body workout could take up to an hour, whereas a split routine could take less time because you're working fewer muscle groups.

    Type

    Finally, the type of exercise you do is the last part of the F.I.T.T. principle and an easy one to manipulate to avoid overuse injuries or weight loss plateaus.

    • For cardio exercise: Cardio is easy to change, since any activity that gets your heart rate up counts. Running, walking, cycling, dancing, the elliptical trainer...there is a wide variety of activities to choose from. Having more than one go-to cardio activity is the best way to keep your body guessing and reduce boredom.
    • For strength training: Strength training also has a lot to offer. It includes any exercise where you're using some type of resistance (bands, dumbbells, machines, etc.) to work your muscles. Bodyweight exercises can also be considered a form of strength training, as well, although building strength will likely require more resistance. you can easily change the type of strength workouts you do, from total body training to adding things like supersets or pyramid training to liven things up.

    How to Use the F.I.T.T Principle in Your Workouts

    The F.I.T.T. Principle is important because it outlines how to manipulate your program to get in shape and get better results. It also helps you figure out how to change your workouts to avoid boredom, overuse injuries and weight loss plateaus.

    For example, walking three times a week for 30 minutes at a moderate pace might be a great place for a beginner to start. After a few weeks, however, your body adapts to these workouts and several things may happen:

    • Your body becomes more efficient at exercise - The more you workout, the easier it is to do the exercises, causing you to burn fewer calories than you did when you started.
    • Weight loss - Your new workouts may cause weight loss which, of course, is a good thing. The downside? You expend fewer calories moving that new, smaller body around.
    • Boredom - Doing the same workout for weeks or months on end can get old, eating into your motivation to exercise.

    It's at this point you want to manipulate one or more of the F.I.T.T. principles, such as adding another day of walking; changing your exercise frequency, walking faster, or add some running; changing the Intensity, walking for a longer period of time; changing the time, or trying something different like swimming or running changing the type of exercise you're doing.

    Even just changing one of these elements can make a big difference in your workout and in how your body responds to exercise. It's important to change things up on a regular basis to keep your body healthy and your mind engaged.

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