When most people undertake an exercise programme they have a clear picture of what they would like to achieve from it. Whether its fat loss, muscle strength, toning, training for a sport or event, its important to note that exercises are NOT created equally.
The muscles, bones, connective tissue and nervous system in your body adapts to the stimulus you provide from your exercise or conditioning, for example doing a lat pulldown exercise with a weight you can only move 5 times will cause the body to increase strength in these different systems, placing emphasis on the primary muscles used. Performing the same exercise with a weight you can only move 8 times, 12 times, 15 times or 20 times will result in a completely different outcome to those muscles.
The variables is your exercise plan is a way a health and fitness professional manipulates
your exercise to maximise your potential of reaching your goals. Just by changing the number of set, rest time in between exercises, the order the exercises are performed, tempo of movement, the length of each set, etc will alter the consequence.
Initially when someone is new to the gym, the main change in the body comes to the nervous system. Essentially you body has to learn the exercise movement and the more you practice the more it becomes a natural. Once the nervous system can sequence the movement, the body is happy to allow you to lift more force as it feels you wont hurt your self. When you are learning an exercise it is important to note that if you lift a weight badly or have a poor running technique then your body will remember those bad movements. It takes 300 repetitions to programme the nervous system but if its a bad movement pattern, it could eventually lead to an injury, it takes 5000 repetitions to correct that faulty movement pattern (Chek 2002). Only perfect practice makes perfect.
It is also important to note that different people progress at different speeds, usually the first 6-8 weeks require neural adaptions but if you did a challenging sport like gymnastics as a child, then your nervous system may only need 3-4 weeks to fully integrate into the movement. If you have been exercising for a while then to get better results you need change your programme every 4-6 week as doing the same plan evoke the law of diminishing returns. You essentially will get less and less gains from your exercise. If you run for 20 minutes the first time you do this you may use 220 calories at ten minute mile pace. After doing this for the a period of 6 weeks your body may only use 160 calories at the same intensities.