A force plate or platform is a special device used to measure the forces exerted on the ground by a body. These forces, called the ground reaction forces (GRF), are measured by a series of sensors on the plate. Force plates are often used in biomechanical research and sports medicine to study human and animal gaits.
Biomechanics is the study of the physical movements of biological organisms, such as the mechanical aspects of human running or the movements of a fish through water. Sports research is closely linked with biomechanics, because it examines the physical science of movement in sports. A force plate allows sports researchers to conduct experiments and collect quantitative data on body movements. This information can be used to learn more about human biomechanics. It also can be useful in medical diagnoses and in developing new sports technologies, such as running shoes.
There are many sizes and types of force plates that have been developed for different uses. The most common design is a rectangular plate that as four sensors, one at each corner. If jumping or single steps are being measured, the device might be only one or two paces in length. Some force plates are designed in such a way that several can be linked together, forming a longer track for analysis of a running gait.
The data from the force plate is often combined with information from cameras or sensors to gain a more complete picture of locomotion. If a running gait is being analyzed, for example, motion of the limbs might also be important. Researchers might study several subjects of differing ability to compare gait patterns and tendencies.
A single pedestal force plate consists simply of the rectangular surface with sensors attached. Multiple pedestal force plates can be used for more advanced studies. For example, in a study of how force is exerted when a person climbs a set of stairs, a series of plates can be placed along a staircase. The versatility of force plates allows for many variations in experiment design.
Although most force plates are manufactured for human usage, they also have applications in biological studies. For example, a force plate can be used to study an equine gait. Data on how a horse trots and walks can be helpful in designing horseshoes for hard surfaces, such as pavement. For this type of study, the typical rubbery surface of the force plate must be modified to resemble pavement using concrete or steel. The horse is led over the plate, which registers information about the horse’s movement and the force that is exerted on the hard surface.
