Rate of Force Development (RFD)

Muscle-tendon stiffness

in biomechanics "stiffness" and "compliance" refer to the amount of deformation of an object (muscles, tendon, fascia) in relation to the amount of force acting on the object. -an athlete can be both super-flexible and still able to demonstrate considerable stiffness (like a high jumper) -stiffness contains structural and contractile components, which means that connective tissues can adapt to become more stiff and muscles can contract faster and harder to create more stiffness

how to increase RFD?

increasing the RFD whilst simultaneously reducing the time in which peak RFD occurs, will result in a left and upward shift in the force- time curve -this shift enables the athlete to produce greater forces in a shorter period of time, ultimately improving their explosiveness - working on maximal strength (peak force output) than combining it with slow to fast SSC exercise will have a higher chance of creating that desired upward shift (higher RFD)

rate of force development (RFD)

is how fast an athlete can develop force or simply is a measure of explosive strength -improving an athlete's RFD may make them more explosive as they can develop larger forces in a shorter period of time -higher RFD's have been directly linked with better performance for jumping, sprinting, cycling, weightlifting

stretch shortening cycle (SSC)

the 'pre stretch' or 'countermovement' action that is observed before the actual movement -ex bending knees and dipping down before a vertical jump (strong of elastic energy within the tendon and the muscle enables us to jump higher -RFD is commonly believed to be manifested during the SSC

SSC-force relationship

the movement is slower with exercise with slow-SSC because they have a longer timeframe to develop force than those with a fast-SSC -this means slow-SSC exercises can typically create higher peak forces but lower RFD -exercises or movements with a slow-SSC produce lower RFD's than fast- SSC movements.

fast-slow SSC movements

-exercises characterized by larger joint displacements (work through a larger range of movement) are typically categorized as slow-SSC movements -exercises with smaller joint displacements are commonly referred to as fast- SSC movements

how to calculate RFD?

1. how much force are we producing? how long did it take to reach that force? avg RFD [N*S^1]=peak force [N]/ time to achieve peak force [s]

positive effects of increased stiffness

1. increase cadence or bouncing frequency 2. decrease ground contact time 3. possibly increase peak force and RFD