The overload concept of exercise program design suggests that an exercise stimulus must be administered at a higher intensity than the body is used to cause physiological changes.
Reaching a plateau, where exercise no longer seems to affect the body stops making any physiological changes, is one of the most typical obstacles faced by the ordinary fitness enthusiast. This occurs because, similar to the Groundhog Day scenario discussed above, repeating the same workouts with the same weight for the same amount of repetitions will not provide enough overload to trigger physiological changes.
Resistance training requires performing enough repetitions to generate momentary exhaustion of the relevant muscles or using a heavy enough resistance to cause fatigue after only a few repetitions to cause an adaptation.
A high-intensity heavy load puts mechanical stress on the muscle, while a high number of repetitions puts metabolic stress on the body.
Both types of stress can activate physiological responses that promote muscle growth and definition. The strain on the affected muscles should be adequate for neurological and structural adaptations, regardless of the amount of weight utilized or the number of reps performed until fatigued.
As a result, intensity and repetitions are the two program design variables most strongly related to the overload principle. The amount of resistance utilized is measured in intensity, which is usually represented as a percentage of the one-repetition maximum for a certain lift.
Another way to express intensity is to indicate the maximum number of repetitions for a specific lift. For example, if a person can bench press 200 pounds for 10 repetitions and cannot execute another rep, 200 is his or her 10 rep maximum.
To assign precise intensities for the exercises in an individual’s fitness regimen, either technique of describing intensity can be employed.
A repeat is a single, independent action of the muscles that provide movement at a joint or sequence of joints. Excentric lengthening, a brief isometric pause, and concentric shortening are the three phases of muscle activation in a repeat.
The number of repetitions assigned to an exercise shows how many times an individual should perform that particular movement. As previously stated, repetitions should be completed until temporary muscular exhaustion develops to produce the appropriate overload to stimulate specific adaptations.
The number of repetitions and intensity have an inverse connection; as the intensity rises, the number of repeats a person can execute falls. Higher-intensity loads can only be moved for a few repetitions before fatiguing, whereas lower-intensity loads can be moved for many repetitions before becoming fatigued. It is not required to subject a client to exhaustive strength testing to determine their one-repetition maximum.