Cardio/Endurance Exercise Program Design Strength Training

The 5 Basic Principles of Fitness

The best way to achieve optimum results in exercise and fitness is to follow a plan. But not just any plan, such as “I’m going to run 5 miles every day” or “I’ll lift the heaviest weight I can every time I work out.” Your body is an amazing machine that responds to specific stimuli in distinct ways, and your brain is constantly working to protect the body from threats – like way too much stress on the muscles and tendons from continuous all-out hard exercise.

Principle (noun): 1. a basic truth or theory;  2. an idea that forms the basis of something;  3. a law or fact of nature that explains how something works or why something happens.

Fortunately, exercise science gives us five basic principles we can incorporate into a fitness program that will develop the changes, or “adaptations” we desire, in a safe and lasting way. These five principles are:

  • The Overload Principle
  • The F.I.T.T. Principle
  • The Specificity Principle
  • The Rest and Recovery Principle
  • The Use It or Lose It Principle

The Overload Principle and the F.I.T.T. Principle work together, so let’s review these first.

The Overload Principle is considered the most important concept in exercise. In simple terms, it means that your body will adapt to the demand you impose on it. For example, when you lift a heavy weight you haven’t lifted before, or you complete a hard cardio workout that puts new demands on your heart and lungs, physiological changes will take place that will allow you to do this more easily next time.

Because the body is so adaptable, the demands we put on it must gradually and progressively increase over time in order to achieve long-term fitness gains. These demands must be applied slowly, because too much too fast causes the body to react negatively to excessive stress. (For more about this concept, read The Body’s Response to Stress – Understanding the General Adaptation Syndrome.)

So it’s important to strategically vary your mode of exercise, intensity and duration of training in order to get better, stronger or faster. This is where the F.I.T.T. Principle comes in.

F.I.T.T. stands for Frequency, Intensity, Time and Type. These are the four areas where increases in workload or demand can be made in order to progressively overload the body so it adapts in the desired way.

Frequency means how often an exercise is performed. After any kind of exercise, your body begins a process of repairing and rebuilding stressed tissues. It’s important to find the right balance of work and recovery that provides just enough stress for the body to adapt as well as recover for the next session.

Intensity is the amount of effort or work completed in a specific exercise. For example, walking at a conversational pace is low intensity, whereas sprinting for 400 yards is high intensity. In strength training, factors that influence intensity are the weight itself (load), the number of sets and repetitions, the tempo of the repetitions, and whether a level of instability has been added (such as standing on one leg while doing shoulder presses.) Once again, just enough intensity to overload without overtraining, injury or burnout is what’s important here.

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Time is simply the duration of the exercise session. It’s a function of intensity and type.

Type means the type of exercise performed – strength training, cardio, or a combination of both. The type of exercise is tied to the Specificity Principle, discussed next.

This table illustrates how to combine the Overload Principle and the F.I.T.T. Principle for strength training or cardiovascular training:

 Strength TrainingCardio Training
FrequencyIncrease the # of workout daysIncrease the # of workout days
IntensityIncrease the number of repetitions for a given loadIncrease pace for a given time or distance
TimeIncrease the number of setsIncrease length of workout or distance
TypePerform a different exercise for the same muscle groupPerform a different type of exercise, ex. running to cycling

The Specificity Principle is, quite simply, that the exercise you do should be specific to your goals. For example, if your goal is simply health and weight management, focus on total body strength, cardio and a healthy diet. If you are a runner wanting to improve your race times, include speed workouts in your training. If you’re a cyclist training for a 100-mile ride, focus on building up longer distance training rides at an endurance pace.

The Rest and Recovery Principle is critical to achieving gains in fitness. The body simply cannot tolerate too much stress, and over time will instead “shut down” in order to protect itself. This results in overtraining syndrome, burnout, excess fatigue, and a weakened immune system. (Read The Body’s Response to Stress – Understanding the General Adaptation Syndrome.) Exercising every day is perfectly fine – just not the same exercise at the same intensity. Especially with strength training, it’s important to allow at least a day between sessions to allow muscles to repair and rebuild. However, working different muscle groups on different days (what’s called a “split routine”) will allow for this recovery period for one muscle group while working another. Low intensity cardio can be done every day, but rest between intense sessions. Rest and recovery are important for your mental state too!

The fifth principle, while not specifically targeted to fitness adaptations, is still important to be aware of – Use It or Lose It. Most everyone is aware of this concept at some level, as it applies to many things in life. With respect to the body, muscles build strength (called “hypertrophy”) with use, and lose strength (“atrophy”) with lack of use. This includes not only the skeletal muscles, but also the heart and even the brain (although it’s not technically a muscle.) How quickly atrophy occurs is dependent on many factors, and will be the subject of a future blog post.

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Incorporating these principles into your fitness routine will ensure you get the best results in the most efficient way, while preventing injury and overtraining.  But it can be complicated. As a virtual fitness coach and personal trainer certified through the National Academy of Sports Medicine (NASM), I have the knowledge and experience to develop a progressive program specifically designed for you and your fitness goal. We’ll work together, on your schedule, to get you where you want to be, safely and effectively. Contact me today for a free consultation!

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