Basis of Exercises

For exercises, while it is true that repetition helps commit to memory, I am not for that “magic number” theory of “20 repetitions and you got it.” I love the fact that we are all unique, so is it any wonder that the number of repetitions it may take one to memorize may not be the same as anyone else? Then how do we know how many repetitions are enough to have the effect an exercise is meant to have or visualize the outcome it is supposed to produce? Basically, it all depends on the intent of exercise or in other words the goal of exercise. 
Exercises are classified on basis of the effect- strengthening, increasing endurance, or range of motion- which used to be primary goals. Nowadays, the goals have diversified to include stability and achieving a good movement pattern in addition to the prior goals. We now have the tools to precisely gauge and progress these objectively as our knowledge of biomechanics, kinesiology, and neurosciences deepens.
Spinal stabilization exercises are probably most widely prescribed, and rightfully so, as all other movement depends on this fundamental ability on which other movements patterns are based. Consider it to be the foundation on which the rest of the body structure is built and given freedom to move. Once the stabilizing muscles fire properly, repetition is key to set this pattern on which any other dynamic movement is based. Even though there may be a foot or knee discomfort or injury, the root cause may lie in the improper spinal stabilization. A physical therapist is hence required to consider the body as a whole and detect where the dysfunction originates. In that context, I love Sherlock Holmes’ quote on elimination: “Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth.” Functional Movement Assessment does precisely that. It looks at whole movement patterns for dysfunction, and then breaks down movements to specific joints and considers surrounding soft tissue to determine where dysfunction originates. That is more often than not a work in progress, and one should be very flexible in making ongoing changes without losing sight of the end goal. So that, for example, if it is the foot or knee with symptoms, while it should be addressed and local symptoms treated, the spinal stability must also be looked into. If not, the symptoms may eventually reoccur or show up at another site, since the fundamental issue may not be resolved. 
To achieve an end goal, the exercise prescribed must be specifically tailored to the individual. While finding dysfunction is like detective work, determining which exercise must be utilized is an art. A physical therapy gym/clinic must be equipped with different choices based on each individual’s preference. For example, a housewife who is a homemaker, may do well without much equipment and is more likely to follow through with the home exercise program with simple exercises just activating the muscles (maybe using the wall or easily available things within the home: tennis balls, strap/belts, cans/bottles, etc). On the other hand, an athlete used to various equipment in a gym may be proficient with foam rollers, balance discs, weights, bands, and multiple other tools employed by a physical therapist and may be likely to follow through with a set home exercise program if it employs such equipment. 
Broaching on the topic of home exercises, it forms a very prominent part of the rehabilitation process, since you see a physical therapist only 1-2 per week. The journey back to wellness is based on an efficient, engaging, and workable home exercise program. A good understanding of the exercise patterns and repetition is key. Sometimes one is diligent with exercise, yet the rehabilitation program may not achieve the goals because of incorrect movement patterns. Ask questions if needed, study your body well, and go with the guidance from the physical therapist. Only you can make that difference in your wellness, and with sincerity and constant eye on the goal, one cannot fail.