Let's quickly take some time to review the important technical terms of force, work, torque, power and endurance. These variables can provide valuable insights into how accurately the athlete is applying their strength and power to a skill. These variables also allow a comparison between athletes. And the technical problems that might exist in the application of strength and power. Knowing how these terms relate to strength and power will help you competently interpret the data provided by technology. The application of force is relevant to all sports skills. It is used to speed up, slow down, change direction, throw, catch and kick a ball. The sprinter uses force to explode out of the starting blocks. And a jumper to jump high and far. Fatigue causes a decline in force and therefore negatively affects the athlete's performance. Now as we said technology can provide data about the athlete's force production while performing. There are hi-tech rowing paddles, for example, that are fitted with pressure sensors. That measure the forces produced at different parts of the rowing stroke. And this enables the rower to determine weaknesses in their rowing stroke. Now work is done when the athlete moves in the direction of the force while simultaneously applying the force. And a good example of this is throwing a baseball. The pitcher applies a force to the ball over a distance before releasing it. A javelin and discus thrower maximizes the work they do on their respective implements. By performing movements that increase the distance over which the force is applied. Work is the method by which the athlete transfers energy to an implement by moving through a relevant range of motion. Work in fact means, movement is occurring. In equation form, Work = Force x Distance, over which the force is applied. Another example, a really neat example, of how work is used in sports is the hockey slapshot. The player uses muscular energy to store potential energy in the stick by hitting the ice before hitting the puck. The energy stored in the stick causes a whip like action in the stick as it contacts the puck. The high speed of the stick's whip transfers energy into the puck. The work performed on the puck is the force applied by the stick. Times the distance over which the force is applied to the puck by the stick. Now power describes how quickly work is done and it's calculated in one of two ways. Power can be calculated as work divided by the time or power equals force x velocity. And the amount of power produced indicates the type of metabolic energy the athlete is using. A high power output demands the effective use of the ATP PC energy system. A moderate power output makes use of the glycolytic energy system. And a low power output uses the aerobic energy system. Now some skills such as the discus throw demand high power output for optimal performance. Others, like endurance running, only require low power. In both situations though, the athlete producing the most power will win their respective competition. A throwing movement is explosive use of ATP PCR energy system. All things being equal, the thrower can tap into this system quickly. And the one who does so as quickly as possible will be able to move more explosively and therefore will win the competition. The winner of an endurance race produces more power output than the loser because of their stronger aerobic energy system. Power is simply used in different ways to win the competition. When you're looking at a thrower versus when you're looking at an endurance runner. Two athletes performing the same skill may do the same amount of work, but their power may differ. For example, two tennis players moving their tennis racket through the same distance while serving will do the same amount of work. However, if one player moves the tennis racket through the serving range more quickly than another player does. The one moving the racket quicker produces most power. The higher the power, the faster the ball will leave the racket. However, in this case, skill not only demands speed, it also demands accuracy. And sometimes moving quicker leads to errors while performing the skill and the advantage of power is lost. An athlete's power is usually more important to understanding the performance outcome than the amount of work they do. It is fairly easy to teach an athlete how to move through the correct range of motion. It is much, much harder to effectively increase their speed of movement through this range of motion. Especially if accuracy is also a factor. Now torque. Torque is a really difficult concept to grasp. It's a rotational force. The body moves when muscles produce a rotational force around a joint. A muscle that generates a high torque produces more force around a joint. And a high joint torque can damage muscles and ligaments. The ACL in the knee for example, limits the movement in the knee. And it is susceptible to damage when torque or rotation through that knee surpasses the strength of these supporting ligaments. Now coaches of sports involving tackling tend to think of a torque in terms of leverage. They teach their athletes how to use leverage and therefore produce a high torque to their advantage. More torque is produced when the athlete uses a long lever. Maximizing the length of the lever to increase torque can help a player overcome a strength deficit when tackling. It also reduces the amount of energy needed to stop the opposing player. In equation form, torque is equal to force applied times the distance from the center of mass at which the force is applied. So what does this mean? Well, a player's center of mass is the average location of mass for the body. In male athletes their center of mass is usually somewhere near their navel. For female athletes, it is slightly lower because they carry more mass in their hips. When a player crouches, the center of mass is low and when the player is standing upright, their center of mass is high. When two rugby players hit the player who is the lowest and has the lower center of mass will win the tackling battle. Less force is needed to rotate the other player when the force is applied as far as possible from the player's center of mass. If a player is hit right at his center of mass, no torque is going to be produced. But you hit him on one side, off the center of mass, and the player will spin. Hit him low, and he can rotate head over heel. Players are taught to tackle by staying low. Because it takes less force and less energy when the force is applied at a long distance from their opponent's center of mass. The common phrase you hear is the low man or low woman wins. The distance the player is hit from his or her center of mass is called the lever or moment arm. So, here's the question, when player A keeps a low center of mass and exerts a force on player B. And player B has the high center of mass. Which player will be rotated? Will it be player A or will it be player B? Now the answer is, if you said player B, you were correct. Player A will rotate Player B because Player B is hit below his center of mass. [BLANK AUDIO]
