Kraemer, W. J., & Newton, R. U. (1994). Training for improved vertical jump. Sports Science Exchange, 7(6), 1-12.

Explosive power is a requirement for success in many athletic skills. This is not to be confused with the common concept of strength. Strength may be talked of frequently and trained commonly but the way it is practiced is not good for many sports. A typical explosive strength action is the vertical jump.

"Dynamic strength is defined as the maximal ability of a muscle to exert force or torque at a specified velocity . . . and is often assessed by using a one-repetition-maximum (1 RM) test, in which strength is defined as the maximal weight an athlete can lift one time through the entire range of motion. However, tests of 1 RM strength are of limited practical value because this specific type of strength is employed in only a few athletic endeavors, such as power lifting. Most sports require the explosive application of force to accelerate the body or limb, whereas 1 RM strength tests do not require rapid acceleration to produce the necessary force. In fact, 1 RM type of strength is maximized during slow muscle actions and minimized as the velocity of movement increases [the faster a movement the less strength that can be used]. Conversely, vertical jump performance requires great power, that is, the ability to exert force rapidly through a vertical distance." (p. 2)

Actions such as throwing a discus, long, high, or triple jumping, starting in a sprint race, and pulling an oar all have speed of movement while overcoming considerable resistance as the primary performance criterion.

Kraemer and Newton list the following features as characteristics of explosive power which need to be measured to analyze strengths and weaknesses in movements and also to design appropriate training programs. The item and test possibilities are those suggested for vertical jump training.

  1. Maximal strength: Tested by quadraceps or leg press.
  2. Maximal rate of force development: Tested by measuring the contact time during a drop jump when jumping for minimum contact and maximal height.
  3. Stretch-shortening cycle ability: Measure the difference between squat jump and counter-movement jump heights.
  4. High-velocity force production: Not easily assessed during a vertical jump. It should indicate the rapidity with which force is applied in a task.
  5. Maximal mechanical power: Measure the highest power output during vertical jumps with increasing loads or increasing drop heights.
  6. Jumping skills and muscle coordination: Assessed by technique analysis, for example, the difference between a jump with and without arm/trunk movement.

This is the capacity that should be trained for maximizing performance where speed and power are demanded. The possibilities for improvement reside in the characteristics cited above however, actual tests have to be adapted to the activity in question.

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