Why You Need to Follow the F.I.T.T. Principle

Follow the FITT principle to achieve your athletic goal, whether it is to increase your endurance, strength or speed.

There are many concepts to consider when developing an exercise program to increase your athletic performance, but every athlete should follow the guidelines of the F.I.T.T. Principle.

F.I.T.T. stands for frequency, intensity, time and type. These four key aspects of your workout program will help you achieve your athletic goal, whether it's to increase your endurance, strength or speed. Here is an in-depth look at what each means and how to modify it to make athletic gains on the field.


Frequency refers to the number of times per week an athlete trains. It depends on many factors, including your sport, personal goals and body parts worked during each training session. For example, if an athlete trains his or her whole body during every session, he or she should train three or four times a week. If an athlete trains individual body parts each session, he or she could train up to six times a week. Increasing the frequency of your workouts should be progressive over time to allow muscles to recover and grow, and to avoid muscle breakdown or injury.


Intensity refers to how hard an athlete works during his or her workout period.

Intensity can be measured two ways—internally and externally. Internally, you can tell how hard you are working by gauging the level of fatigue or exhaustion you are feeling. Externally, you can measure your intensity with a device like a heart rate monitor.

Training at different intensities benefits different athletes in different sports. Endurance athletes benefit from training at a lower intensity for longer periods of time, whereas football and basketball players benefit from short bursts of high-intensity training.

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Time refers to the length of an athlete's workout. Sports that require continuous activity, such as cross country, require athletes to train for long periods of time. The opposite is true for athletes who perform activities for short bursts.

The amount of time you exercise also determines which energy system your body uses. During exercise lasting less than 10 seconds, such as a sprint, the body uses the phosphagen system to produce a quick jolt of a massive amount of ATP, which it uses for energy. During exercise lasting 30 seconds to 2 minutes, the body uses glycolysis, which also produces ATP for all-out exercise. Finally, exercise lasting longer than 2 minutes requires the body to use its aerobic system to produce energy. Athletes should progress the amount of time for each workout in small increments to allow for acclimation.


Type refers to the specific physical activities an athlete engages in to achieve his or her individual goals related to his or her sport. If you're looking to increase muscle mass and strength for football, you should perform powerful and explosive strength movements in the gym and on the field. If you're goal is to increase your foot speed and quickness, you should perform speed drills and fast-paced exercises to increase reaction time and train your fast-twitch muscles. The type of training an athlete performs should mimic the movements and strengths needed for his or her individual sport.

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