Power consist of both speed and strength. Strength is increased by repeatedly stressing the target muscle groups over time. There are three common ways of creating the required stress, isotonic, isometric and isokinetic exercise. Isokinetic exercise requires exercise machines.

Normal muscle movement is isotonic. One muscle lengthens while the other contracts in complementary pairs, A good example of isotonic movement is weight training. As you lift the weight and then return it to its original position you muscles lengthen and contract alternately through the full range of motion.

To understand isometric exercise, imagine you try to lift the same weight and it does not move. No matter how hard you work it remains in the same place. The muscular response you experience when applying force against an immovable object such as this is an isometric contraction. One muscle lengthens and the opposing muscle is prevented from contracting because the stationary weight prevents the muscles from moving through their range of motion. Building muscle tension in the muscle while preventing it from shortening was once thought to bring dramatic gains in strength. Studies of isometric exercise have since proven it to be an effective, but not miraculous, way of improving strength gradually.

One drawback of isometric exercise is that the muscle is strengthened only in the exact position of the isometric contraction. If you push against the floor with your elbow bent at a ninety degree angle, your arm muscles are strengthened in that position, but you have to repeat the pushing at eighty degrees, seventy degrees and every position between. Doing simple push-ups, an isotonic exercise, can be more efficient because you work the entire range of motion, and strengthen the corresponding muscles, in a single action.

The key to effective and consistent strength gains is to apply the proper amount of stress in the correct way at the proper frequency. Too much stress cause time-loss injuries, injuries that require you to take time off from your exercise program to recover. Taking time off means you have to start over where you left off, or more likely, at a lower level than when you were injured. To prevent overuse and stress injuries, work at the pace. Don’t try to get in shape quickly by doing 200 sit-ups on your first day. Start with a comfortable number of exercise.

To determine a good number of repetitions, work through as many repetitions as you can until you feel minor discomfort in your muscles. Do a few more repetitions and stop there. Stay with this number until you can complete it without difficulty and then add a few more repetitions. The last ten to twenty percent of the repetitions should always be fairly difficult to complete. A gradual increase in the work load allows you to reap maximum benefits with minimal injuries.

Cheating on an exercise to squeeze out a few extra repetitions does more harm than good in the long run. Failing to flex your arms fully during push-ups may allow you to do ten more than usual, but it has less effect on your arm strength than push-ups done correctly. If you can do only five push ups correctly, then do just five. If you stick to the correct form and are consistent, five will turn into ten and ten into twenty and so on.

Each exercise is designed to work specific muscles and produce specific benefits. Make an effort to understand what benefits are and stick to the correct way of performing each movement.

For best results, do strengthening exercises two to three times a week. Strengthening training causes minor tears in your muscle fibers that need about forty-eight hours to heal fully. During the recovery period your muscles become stronger and thicker creating the increases in size and strength that you are training so hard to achieve. When you interrupt the recovery period, you hinder the efforts of your body to produce the results you want.