Principle of Progressive Overload

In order to become more fit, you must push your body just a little harder than you've pushed it before. You can use the FITT Principle to guide you:

Frequency: Get fitter by exercising more often. If you run twice a week, try running 3 or 4 times a week. If you play pick-up soccer with your friends on Fridays after school, organize extra games over the weekend. Stretching more frequently is the best way to improve your flexibility - every day is ideal.

Note that frequency does not apply to strength training because your muscles need at least 48 hours to recover. If you're already doing resistance training 3 times a week, the best way to get stronger is to increase your...

Intensity: Get fitter by exercising harder! Run faster, jump higher, and take less rest so your heart rate stays up. Upping the intensity of your workout is the best way to improve your cardiorespiratory endurance, anaerobic capacity, and muscular endurance. It is the ONLY way to increase your muscular strength, in the long run.

The Principle of Progressive Overload is usually used by weight lifters. In order to get stronger, they gradually add weight to the bar every week or every workout. Since I recommend that you wait to lift weights until high school, you can increase the intensity of your body weight exercises by moving up to a more difficult version of the same exercise.

Time: Get fitter by exercising for longer periods of time. Run for 2 miles instead of 1. Play 3 pick up games instead of 2. Increasing the time you spend exercising will benefit you most in terms of cardiorespiratory endurance, muscular endurance, and flexibility.

Type: Get fitter by doing a wide variety of exercises. When your body gets used to a particular type of exercise, your body becomes more efficient. This is a good thing, but it also means that your body doesn't have to work as hard to do something familiar. Do many types of exercises and your body will have to work extra hard to adapt - and your physical fitness will dramatically improve.

Sets, Reps, and Rest Intervals

Resistance training workouts are usually described in terms of sets and reps.


     Rep: Short for repetition. How many times - in a row - that you perform an exercise.

     Set: A set is a collection of reps that you do without stopping for rest.

     Rest Interval: The amount of time that you spend resting between sets.

Resistance training workouts will usually be written like this: Sets x Reps, Rest Interval. (Sets x Reps is pronounced Sets times Reps.) Example:

     Pushups: 3x20, 30 seconds rest

This means that you would do 3 sets of 20 reps, with 30 seconds rest between sets - 20 pushups, 30 seconds rest, 3 times.

Athletes use different numbers of sets and reps, and take more or less rest, depending on their goals for the workout. In general, higher reps, lighter weights, and less rest are used to develop muscular endurance. Lower reps, heavier weights, and longer rest intervals are used to improve muscular strength. Read more about it here.