A primary goal of exercise training is to stimulate various physiologic adaptations in your body to either improve general health or athletic performance (or both depending on personal exercise goals).  To produce a change, the desired physiologic process (e.g. muscular hypertrophy) needs to be challenged on a regular basis by exercises that specifically tax that particular physiologic system (e.g. strength training exercises).  This is known as the principle of adaptation; and, it is one of the principles of physiologic conditioning that, when appropriately applied, leads to progress in your exercise training. 

     The principle of overload is another important application and it is related to the principle of adaptation.  This concept states that the physical demands placed on your body must exceed the stresses of daily life in order to enhance physiologic function.  For example, aerobic exercise challenges the cardiovascular and musculoskeletal systems resulting in adaptations that make these systems more efficient.

     To acquire adaptations from the principle of overload, the principle of progression needs to be applied.  The principle of progression involves the manipulation of the frequency, intensity, and duration of the exercise to create a training regimen that continues to challenge your body's systems.  Once you have achieved a certain fitness level, you need to either increase the number of days per week you exercise (frequency), how hard you exercise (intensity), or the length of the individual exercise sessions (duration) in order for further gains in fitness to be achieved.  To avoid injury, progression should be done in small increments.  And, intensity and duration should not be increased at the same time.

     The principle of specificity is another important factor related to proper exercise training.  It states that the adaptations to exercise are specific to the metabolic and physiologic systems used during the exercise.  Your body adapts differently to aerobic exercise than it does to resistance training.  Therefore, you should engage in the type of exercise that meets your fitness goals.  For example, only participating in strength training exercises will not help you to run a marathon because this form of exercise will not sufficiently tax the cardiovascular system for such an endeavor.

     The principle of individual response explains why there are individual variances in the adaptations to the same type of training.  The same state of fitness or athletic performance will not be achieved among persons initiating an aerobic dance class at the same time due to such factors as genetics, health status (e.g. presence of chronic diseases), current fitness and nutrition levels, motivation, amount of sleep, and environmental factors.  Therefore, an exercise program should be tailored to meet your individual needs and abilities.

     The principle of reversibility states that the metabolic and physiologic adaptations to exercise are lost when participation in regular exercise is discontinued.  This detraining response can occur in just 1 -2 weeks.  Therefore, a year-round fitness program should be maintained to remain fit.

     To get the most out of your exercise sessions follow the above principles.  Properly applying them in your daily fitness routine will help you to achieve your health, fitness, and athletic performance goals.

Note:  Before beginning an exercise program or increasing the intensity level of a current routine, a physician's approval should be obtained, especially for older adults and those at risk for or who currently have chronic health conditions.

Resources

Exercise Physiology Energy, Nutrition, & Human Performance, sixth edition, McArdle, WD., Katch, FI., and Katch, VL.

Fitness & Health your Complete Guide to: Aerobic Fitness, Muscular Fitness, Nutrition, Weight Control, Sharkey, BJ., and Gaskill, SE.