Basic Principles of Resistance Training - Dr. William Kraemer
It is important to understand some of the basic principle of resistance training. When undertaking a needs analysis for a training program, there a few underlying principles to consider:
Progressive overload is an overarching principle stipulating that one needs to increase the exercise demands in order to see progression in a performance variable, as defined within the construct of the variable being trained for (i.e., strength, power, or local muscular endurance). Progressive resistance exercise or progressive overload refers to the need to continually increase the stress placed on the muscle as it becomes capable of producing greater force, greater power or has more local muscular endurance. For strength, at the start of a training program the 5 repetition maximum (5 RM) for the bench press might be 225 lb, and is a sufficient stimulus to produce an increase in strength. Later on in the training program, 5 repetitions at 225 lb would not be a sufficient stimulus to produce further gains. The muscles involved can easily perform 5 repetitions with 225 lb and consequently 5 repetitions with 225 lb is no longer a 5 RM or a sufficient stimulus to further increase strength. If the training stimulus is not increased at this point, no further gains in strength will occur.
Several methods can be utilized to progressively overload the muscle. The resistance (amount of weight utilized) to perform a certain number of repetitions can be increased. The use of RMs automatically provides progressive overload because as the muscle's strength increases the amount of resistance necessary to perform a true RM also increases. For example, a 5 RM may increase from 225 lb to 245 lb after several weeks of training. Another method of progressively overloading the muscle is to increase the volume of training performed (i.e., the number of sets and repetitions of a particular exercise). An important corollary is that progression must be varied as directed by the principle related to periodization of resistance training (see below); so that overtraining is minimized or eliminated in an exercise prescription.
Specificity of Training
This is very much the underlying principle of any exercise program. Training is specific to the type of program utilized and only those muscles that are trained will adapt and change in response to a resistance training program. For example, light resistance will not activate many motor units and therefore the muscle fibers contained in other motor units will not be trained nor adapt to the loading. In addition, training upper body only will not influence the lower body muscle fibers. Thus, resistance training is specific to the motor units that are activated and their influence on physiological systems to support their homeostasis, repair and remodeling.
The SAID principle is the acronym for specific adaptations to imposed demands. This means that the adaptations to resistance exercise are specific to the demands of the program (which, in turn, are determined by the acute program variables). This principle is an extension of the concept of specificity and underscores the importance of the exercise prescription in targeting those features of adaptation that are influenced by a specific resistance training program. These adaptations are dependent upon the exercise range of motion and specific mode. For instance, isometric exercise may increase strength, but only at the specific angle the exercise is performed at.
Periodization of Training
Prioritization of Training
In order to eliminate the potential for overtraining and boredom in resistance training, variation in the exercise stimuli is vital. Periodization of training involves the systematic manipulation of the acute program variables over time with planned rest periods used to provide recovery, as opposed to the standard progressive overload method in which the repetition range remains constant for several weeks while the weight is increased as strength allows. Unloading or lighter cycles or workouts also provide the body with recovery periods needed for optimal training. Both the classical linear periodization program, which manipulates workout protocols over each week within 4 week microcycles, and the non-linear method, which manipulates intensity, volume, and other acute program variables within a week, have been shown superior to standard progression programs6-9.
With any total conditioning program, one has to prioritize the training goals. Even within a periodized program the trainable goals for resistance training are maximal strength, power, local muscular endurance and muscle hypertrophy. Many of the other systems adapt as well in support of these training goals (e.g., connective tissue). Thus, each training cycle needs to have a training priority based upon the goals of the individual.