A22 Failures in Energy Transfer

Topic

An athlete's kinetic chain generally suffers an energy transfer failure whenever it fails to efficiently transmit energy—generated in a proximal muscle—to its final point of application, whether that point is a distal extremity of the athlete's body or an external implement they are holding. Conversely, the athlete's core acts as the transmission link between their lower and upper body within this kinetic chain; a deficiency in core stiffness consequently reduces the overall efficiency of energy transfer between the two sections, mirroring the loss of stiffness described in another model within this set regarding a degraded spring-mass system. If core stiffness is even lower, the final efficiency of energy transfer between the athlete's lower and upper body is reduced even further.

In contrast, improper temporal coordination between two consecutive segments of the kinetic chain causes a different type of energy transfer failure—specifically when one segment activates too early or too late relative to the other, mirroring the premature kinetic chain disruption described in another model within this set regarding a sports throw. As the timing of this segment's activation deviates further from the optimal activation of the adjacent segment, the final energy transfer between the two segments deteriorates even more. Conversely, soft-tissue deformation at a specific point of this energy transmission dissipates a portion of that same energy at that very point—much like the energy loss due to deformation described in another model within this set regarding a degenerated tendon—while excessive muscle co-activation between an agonist and its antagonist dissipates an additional portion of that energy, mirroring the synchronization failure between the two muscles described in yet another model in the set. Consequently, if this excessive co-activation between the muscles is further increased, the resulting energy dissipation at this transmission point also increases.

Thus, given this central core and the transmission link with which the model began, the coupling power between two adjacent segments of the kinetic chain—quantified by the Putnam model describing such intersegmental transfers—becomes negative precisely when a distal segment absorbs energy from its adjacent proximal segment rather than receiving it; this proves counterproductive for the entire kinetic chain. Consequently, moderate energy loss along the kinetic chain reduces the final velocity of the distal end by a smaller yet equally significant margin, whereas active control of the central core stiffens the athlete's lumbopelvic joint, thereby reducing losses within the critical transmission region that characterized the model's initial setup.

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