When engaged in any fitness training program there are several universally accepted scientific training principles that must be followed in order to improve conditioning and performance. These principles are:

The Principle of Individual Differences

Because we are all different people we will respond differently to exercises. A proper training program should be modified to take individual differences into account.

Some considerations are:

• Large muscles heal slower than smaller muscles.
• Fast or explosive movements require more recovery time than slow movements.
• Fast twitch muscle fibers recover quicker than slow twitch muscle fibers.
• Women generally need more recovery time than men.
• Older individuals generally need more recovery time than younger individuals.
• The heavier the load lifted, the longer it will take the muscles to recover.

The Principle of Overload

The principle of overload states that a greater than normal stress or load on the body is required for training adaptation to take place. The body will adapt to this stimulus. Once the body has adapted then a different stimulus is required to continue the change. In order for a muscle (including the heart) to increase strength, it must be gradually stressed by working against a load greater than it is used to. To increase endurance, muscles must work for a longer period of time than they are used to. If this stress is removed or decreased there will be a decrease in that particular component of fitness. A normal amount of exercise will maintain the current fitness level.

 The Principle of Progression

The principle of progression implies that there is an optimal level of overload that should be achieved, and an optimal time frame for this overload to occur. Overload should not be increased too slowly or improvement is unlikely. Beginners can exercise progressively by starting near threshold levels and gradually increasing in frequency, intensity, and time within the target zone. Exercising above the target zone is counterproductive and can be dangerous.

The Principle of Adaptation

The body adapts to stress in a highly specific way. Adaptation is the way the body ‘programs’ muscles to remember particular activities, movements or skills. By repeating that skill or activity, the body adapts to the stress and the skill becomes easier to perform. Adaptation explains why a beginning exercisers are often sore after starting a new routine, but after doing the same exercise for weeks and months the athlete has little, if any, muscle soreness.

The Principle of Use/Disuse

The Principle of Use/Disuse implies that you “use it or lose it.” This simply means that your muscles hypertrophy with use and atrophy with disuse.

The Principle of Specificity

The Specificity Principle simply states that a training program must go from highly general training to highly specific training. For example, if you are a beginning exerciser, you may start out with a easy general strength training program before moving on to more specific training in the way of plyometrics or kickboxing. The principle of Specificity also implies that to become better at a particular exercise or skill, you must perform that exercise or skill.