Module 3: The FITT Principle
What is the FITT Principle?
The FITT principle is an acronym for the framework of exercise prescription:
- Frequency
- Intensity
- Time
- Type
Frequency
Frequency refers to how often you exercise. Usually the number of days a person performs an activity is used to determine the frequency.
How often you should exercise depends on the specific FITT components you are trying to develop. For instance, if you are targeting cardiorespiratory endurance, the suggested minimum frequency for moderate intensity is five days a week and three days a week for vigorous intensity. However, if you are targeting muscular strength, the recommended frequency is two to three days a week working on each major muscle group.
Remember, for exercise to be effective it must be performed on a regular basis.
Write it down: Finding time to workout can be challenging. Plan ahead and work it into your daily schedule by writing it down. It may help you stay on track.
Intensity
Intensity refers to how hard you exercise. In order for a muscle (including the heart muscle) to get stronger, it must be “overloaded” or worked against a load greater than what it is normally accustomed to working. This principle of fitness is known as overload.
For example, to increase muscular endurance, muscles must be exposed to sustained exercise for a longer than normal period of time. If overload is less than normal for a specific component of fitness, the result will be a decrease in fitness for that particular component. Conversely, a normal amount of exercise will maintain fitness level.
Begin at the beginning: If you are new to exercise, begin by considering your current fitness level and goals. Begin with caution and make slow but steady progress over time.
Categories of Intensity:
Light or Leisure-time
Light intensity exercise refers to a level of exercise that does not cause you to break a
sweat or produce shortness of breath.
Light physical activity is exercise, sports, recreation, or hobbies that are not associated with one’s regular job duties, household or transportation. Activities performed at a light intensity are not enough to show a health benefit from exercise, but still may be fun and enjoyable.
Examples:
- Walking slowly
- Fishing
- Housework (cleaning windows or vacuuming)
- Golfing while riding a golf cart
- Conditioning exercise, light stretching
or warmups
Moderate
Moderate intensity exercise refers to a level of exercise in which a person should experience an increase in breathing and/or heart rate.
Moderate exercise corresponds to a 4 to 5 on the RPE scale and 3 to 6 METs (see Measuring Intensity: RPE, MET, and
Talk-sing Methods).
Moderate intensity exercise is enough to produce health benefits associated with exercise.
Examples:
- Walking briskly
- Golf, pulling or carrying clubs
- Recreational swimming
- Doubles tennis
- Bicycling 5 to 9 mph on level terrain or with a few hills
- Weight lifting, Nautilus machines or free weights
Vigorous
Vigorous-intensity exercise refers to a level of exercise that presents a substantial challenge to an individual and refers to a level of effort in which a person should experience a large increase in breathing and/or heart rate.
Vigorous exercise corresponds to a 5 or greater on the RPE scale and greater than 6 METs (see Measuring Intensity: RPE, MET, and Talk-sing Methods).
Examples:
- Race-walking, jogging or running
- Swimming laps
- Mowing lawn, hand mower
- Tennis, singles
- Bicycling more than 10 mph, or on steep uphill terrain
How do you determine your exercise intensity?
That’s dependent on the aspect of fitness. Several methods are described in the following pages.
Measuring Intensity:
Heart Rate Reserve Method
The Heart Rate Reserve method is based on the relationship between heart rate and exercise intensity. As you increase exercise intensity, your heart rate will increase linearly until you reach your maximum heart rate (the rate a person can achieve during maximal physical exertion). The heart rate reserve method uses your estimated maximum heart rate and your resting heart rate to calculate a target heart rate zone sufficient to improve cardiorespiratory endurance.
Here’s how to calculate your heart rate reserve:
- Calculate your resting heart rate.
The resting heart rate should be taken first thing in the morning before getting out of bed. Resting heart rate can be taken on the carotid artery, using two fingers to the right or left of your Adam’s apple or midline of your throat, or on the radial artery located on the thumb side of your wrist with your palm turned up. Do not take your heart rate using your thumb, because it has a pulse of its own. You should take your resting heart rate for a full minute. - Calculate your maximal heart rate by subtracting your age from 220.
- Calculate your target heart rate zones using the following formulas.
The first formula calculates a target heart rate at 65% of your maximum heart rate. The second formula listed calculates the target heart rate at 80% of your maximal. Obviously working at 65% is going to be less intense than 80% of your maximal heart rate. - (Maximal Heart Rate – Resting Heart Rate) * .65 + Resting Heart Rate
- (Maximal Heart Rate – Resting Heart Rate) * .80 + Resting Heart Rate
a. (Maximal Heart Rate – Resting Heart Rate) * .65 + Resting Heart Rate
b. (Maximal Heart Rate – Resting Heart Rate) * .80 + Resting Heart Rate
Once you have your target heart rate zones, you can check your heart rate during exercise to determine if you are exercising within your projected range. You can take an exercise heart rate at your carotid or radial artery for 15 seconds during exercise and then multiple the value by 4 for your exercise heart rate.
RPE, MET, and Talk-sing Methods
The rating of perceived exertion (RPE) method is a subjective measure of how you feel during exercise on a scale of 0 (nothing at all) to 10 (extremely strong). This feeling should encompass all the sensations that you feel during exercise and should not focus on one specific part of your body. For example, to rate how hard you are working, take into account how your legs, arms, chest and breathing feel to you, not just how your legs feel. A RPE of 4 or greater is necessary to achieve the health benefits of physical activity (ACSM, 2014).
The metabolic equivalent (MET) method measures the energy required by the body to complete an activity. One MET is the energy required by your body at rest, whereas 10 METs is the energy required to exercise 10 times greater than when you are resting. You may see a MET value when you are exercising on a treadmill or other cardiovascular equipment. Any activity that requires 3-5.99 METs is classified as a moderate activity and an activity that requires 6 METs or greater is classified as a vigorous activity.
The talk-sing test method is a very simple way to determine the level of intensity of a physical activity. A person who is active at light intensity level should be able to sing while doing the activity. One who is active at a moderate intensity level should be able to carry on a conversation comfortably while engaging in the activity, but not be able to sing. During vigorous activity a person may become too out of breath to carry on a conversation.
Time
Time refers to the duration of exercise. Exercise must be done for a significant length of time to be effective. Generally, an exercise period must
be at least 10-15 minutes in length to be effective. However, the appropriate duration of exercise is related to intensity, frequency and the type of exercise.
For example, if you are exercising vigorously, then you may only be able to complete the activity for 20 minutes, but if you are exercising moderately you may be able to complete the activity for 45 minutes.
What about HIIT training? High-Intensity Interval Training, or HIIT, mixes high intensity with low intensity or rest cycles. Because you are doing high intensity within your workout, the time period for training can be decreased. For example, you can do 10 sprints for 40 seconds each for a total of 10 minutes versus running at a steady pace for 30 minutes. HIIT training cycles can last from 5 seconds to 8 minutes and are performed at 80-95 percent of maximal effort.
Type
There are four major types of exercise:
- cardiorespiratory endurance
- muscular endurance
- muscular strength
- flexibility
Cardiorespiratory endurance is the ability of the heart blood vessels, blood and respiratory systems to supply fuel, especially oxygen, to the muscles and the ability of the muscles to utilize fuel to allow sustained exercise. Examples of cardiorespiratory endurance exercises are jogging, swimming and biking.
Muscular endurance is the ability to repeatedly contract a muscle or muscle groups against resistance. To improve your muscle endurance, try cardiorespiratory activities such as walking, jogging, bicycling, or dancing.
Muscular strength refers to the maximal tension or force produced by a muscle or muscle groups. The key to making your muscles stronger is working them against resistance, such as weights or gravity. If you want to gain muscle strength, try exercises suchas lifting weights or doing exercises such as push-ups, lunges, or squats where you use your body weight as a means of resistance to work against gravity.
Flexibility refers to the range of motion in a joint or group of joints. If you want to improve your flexibility, try activities that lengthen the muscles, such as yoga or a basic stretching program.
Stay motivated: If your exercise routine starts to get boring, set new goals or try a new activity.
Summary
When determining your exercise routine, you should think about the frequency, intensity, time and type of activity. These components influence each other.
For example, if you are participating in vigorous exercise, then you can reduce the frequency or duration. If you are performing moderate activity, then you can increase the duration and receive similar health benefits compared to a shorter bout of vigorous exercise.
References
American College of Sports Medicine. (2014). ACSM’s resource manual for guidelines for exercise testing and prescription. Baltimore, MD: Wolters Kluwer Health/Lippincott Williams & Wilkins.
You have reached the end of Module 3. Please complete the Assessment.
Then, if you feel ready to learn about being active for a lifetime, you can move on to Module 4.