Force Plates are gaining a lot of attention these days, thanks to their ability to assess balance, explosive power and how quickly we develop force when doing a movement.
When talking about something like jumping, there are a number of factors involved, such as weight, acceleration, frictional force, etc. But for simplicity sake, let’s say an athlete can squat their body weight only, and they have a vertical of 16 inches. The athlete trains, and can now squat twice their body weight, and they are tested again, and they have managed to increase their vertical to 24 inches. The athlete continues to train and can now squat 3 times their body weight, however when tested again, their vertical jump did not increase despite gains in strength. Why?
When an athlete preforms a movement, like jumping, gains in strength (Maximal Force) do not necessarily translate to jumping higher. The reason for this is the very short duration of the delivery phase – the athlete does not have the time to develop Maximal Force. In such situations, explosive strength, not the athlete’s maximal strength is the critical factor. Explosive Strength is the ability to exert maximal force in minimal time.
Explosive Strength = Peak Force / Time to Peak Force
What happens when an athlete perfects a movement is that the movement begins to become faster, – this also means the time of motion gets shorter. Therefore, the better an athlete is at a movement, the greater the role that the Rate of Force Development plays in the achievement of high level performance.
The rate of force development (RFD) is a measure of explosive strength, or simply how fast an athlete can develop force – hence the ‘rate’ of ‘force development’. This is defined as the speed in which the contractile elements of the muscle can develop force. Therefore, improving an athlete’s RFD may make them more explosive as they can develop larger forces in a shorter period of time. Developing a more explosive athlete, may improve their sporting performance. In fact, higher RFDs have been directly linked with better jump, sprint, cycling, weightlifting, and even golf swings.
Many coaches and athletes make the mistake of training maximal muscular strength to improve a movement when the real need to is develop rate of force.
Velocity is a major factor when talking about Force, which is what force plates are very good at measuring. Motion Velocity increases when External Resistance decreases. For example, if an athlete remained the same strength and explosive power and lost 20 pounds; their velocity would increase because their resistance (body weight) has decreased.
It is impossible to exert a high force in very fast movements. If an athlete performs the first phase of a movement too fast, the ability to apply great force in the second phase may be somewhat diminished. For instance, too fast a start in lifting a barbell from the floor may prevent the athlete from exerting maximal force in the most advantageous position – when the barbell is at their knees.
The RFD is commonly believed to be manifested during the stretch-shortening cycle (SSC). Depending upon the duration of the stretch-shortening cycle (SSC), exercises are classified as either slow- (≥250 milliseconds) or fast-SSC (≤250 milliseconds) movements. For example, a countermovement jump (CMJ) is classified as a slow-SSC movement as the duration of the SSC lasts approximately 500 milliseconds. On the other hand, sprinting is classified as a fast-SSC movement as duration of the SSC last between 80-90 milliseconds.
To find out more, email us at Zybek Sports, as we custom design our force plates and do not have them on the site.