What is sport specific power?
The limiting factor in nearly all sporting movements is time. In order to run, jump, and sprint the body must perform movements within a given time. The determining factor in how fast a movement is completed is the velocity (V) of the muscular contraction. What determines the change in this velocity is force (F). But remember, the only transferable amount of force that can be produced is the force that is developed within the given sport specific time frame, which is why two athlete can perform the same movement a vertical jump in the same period of time, but with different amounts of force. This leads use to the necessary inclusion of both force and velocity, which is why the biggest indicator in sport performance is Power (P). However, its not just about absolute power, but its power within a given time frame.
Power = Force X Velocity
***It is important to note the only power that can be expressed on the field is the power that is developed at or faster than the speed of velocity necessary for sport (velocity or sport specific power).
Sport specific power is the power that can be developed at or faster than the velocity required for sporting actions. Any force that can be developed slower than sport specific velocity is not transferable and cannot be displayed during the sporting movement.
The relationship between force and velocity
As discovered by Hill in (1948, 1964) force and velocity have a hyperbolic relationship in a single muscle fiber (recently has been shown to be more linear in dynamic movements). The nature of the hyperbolic curve may be slightly different per individual, but the concept still remains the same. Each velocity corresponds with a given percentage of force. In other words the amount of force is dependent on the velocity of the movement.
Velocity is on the Y-Axis, Force is on the X-Axis (Load) and Power is on the opposite Y-Axis. The solid line represents the hyperbolic force-velocity relationship. Each velocity point corresponds with a given force output.
This information informs us that force should not be analyzed unless it is given a context (specific time) and same goes for power in regards to velocity. Remember, power is Force X Velocity, which means that the same level of power can be achieved by either increasing force or by increasing velocity. However, as we have noted above, it may be more important to note increases in power over a specific velocity range. This does not mean training at slow velocities are bad. It just means use the best methods to increase power at these velocities. Velocity specific power can be used to better track and measure progress. It can be used as a sort of field test to validate your training methods. If power at a specific velocity is not increasing from your training (whatever style of training you are using) then you may want to reevaluate its effectiveness.