The athlete's strength and power is related to their sports performance even though the skill is made up from very simple joint movements that don't necessarily require much strength. This simple elbow flexion and extension for example, can be performed with very, very weak muscles. Even a very old lady can do this movement. A very old lady can also throw a ball that involves elbow flexion and extension. However, she won't be able to throw the ball very fast or very accurately. The amount of force she produces will be very low. The amount of work done that is, her range of motion preparing for the throw will be small, and this will affect her ability to throw the ball very far. The amount of torque she produces around her joint will be minimal, and this will affect her ability to use her bodies intricate system of levers and pullies that are fundamental to human movement. Because our old lady cannot produce much force, she will not be able to accelerate her arm to put any kind of speed on the ball. She'll also lack flexibility, resulting in small elbow and shoulder movements. This reduces the amount of torque she can produce at the elbow, shoulder, and wrist joints. Her power and rate at which that power can be applied will be low. And her muscle endurance will limit her throwing a ball two to three times before she fatigues. Application of the athlete's strength and how fast strength can be applied in the correct proportion, and timing determines a successful throw and these are all absent from our old lady. Throwing a dart, and throwing a baseball, and throwing a javelin or throwing a basketball free throw, all require some variation of strength and power, depending on how the skill is performed. Throwing a dart for example, does not demand a great deal of strength or power, and unlike throwing a football or baseball, the shoulder does not move. The way in which strength and power is used to perform a sport skill is therefore an important consideration when designing an athletes' strength and power enhancement program. Transfer of strength, and power developed through the selection of the correct auxiliary exercises is critical to the athletes improved performance. Now research by Wilson and colleagues in 1996, illustrates the importance of transfer effect of training to a sports performance. Athlete's trained for eight weeks using squat exercises, they had a 21% gain in the one repetition max or 1RM for the squat and this is indeed quite impressive. However, of more interest to a coach is how this increase in lower body strength translated into jumping and sprinting performance. There was a 21% improvement in vertical jump performance, and a 2.3% in the 40 meter sprint performance. Now this illustrates that the squat exercise does a good job of transferring, to the performance of athlete's who must jump high such as basketball and volleyball players. However, there is very limited transfer to the athlete's sprint speed. The most important consideration when prescribing strength and power training therefore, is how well the training effects transfer to the athlete's performance. And you will recognize this as the principal of specificity. Structural adaptations stimulated by training depend on the nature of the imposed stress. And this way, the principle of specificity and the transfer of training are very, very highly related.
