Muscle activation history at different vertical jumps and its influence on vertical velocity

The Difference Between Countermovement and Squat Jump Performances: A Review of Underlying Mechanisms With Practical Applications

“…These findings indicate that the storage and utilization of elastic energy plays a role in both the SJ and CMJ. However, as previously stated, the results from computational modelling and experimental studies suggest that it cannot explain the difference between the jumps because only a small amount of extra energy is stored in the tendinous tissues during the countermovement in the CMJ (2,7,50), whereas a significant portion of energy is lost as heat during the execution of a CMJ as compared with the SJ (1,7,45,77,78). Nonetheless, it is important to distinguish between slowly executed, submaximal, and large-amplitude CMJs and faster, maximum effort, and small-amplitude CMJs.…”

“…Although some studies indeed show that the fascicles lengthen during the downward phase of a CMJ, this lengthening is mostly passive and occurs primarily, but not exclusively in monoarticular muscles (28)(29)(30). Furthermore, studies also show a shortening of fascicles (28,50) or suggest an isometric action of the contractile element during the downward phase of a CMJ (45,46). Therefore, there is usually no active lengthening (i.e., eccentric action) of the fascicles during the downward movement of the CMJ.…”

“…Therefore, there is usually no active lengthening (i.e., eccentric action) of the fascicles during the downward movement of the CMJ. The fascicles may passively lengthen only during slowly executed, submaximal, and large-amplitude (i.e., deep countermovement) CMJs, thereby dissipating energy, whereas they remain isometrically or concentrically contracted during faster, maximum effort, and small-amplitude jumps (45,46,68). Hence, it can be recommended that future research refers to the downward and upward phases rather than to the eccentric and concentric phases of a CMJ and avoids the use of terminology that refers to an eccentric phase (e.g., eccentric utilization ratio).…”

“…It is thought that residual force enhancement also occurs during a CMJ, and it could therefore partially explain the superior acute performance during a CMJ. However, the contribution of residual force enhancement to an enhanced force production during a CMJ is likely minimal because the muscle fibers may only lengthen during slow large-amplitude CMJs (45,46,68) while remaining isometric (45,46) or contracting concentrically (50) during fast and small-amplitude CMJs. In addition, when muscle fibers lengthen during the downward phase, it is usually passive lengthening (28)(29)(30).…”

The effect of Short-term Plyometric Training Program on Sprint, Strength, Power and Agility Performance in non-athletic Men

“…These neurophysiologic changes together may improve the ability to store and release elastic energy during the stretchshortening cycle. Specifically, upon landing after a depth jump, an increased level of pre-activation enables the muscle sarcomeres to maintain their length, while the tendons keep elongating and store elastic energy 32 . The second finding of the study showed that PT is effective on the 30 meters run and reduce its time.…”