Braking Impulse in the counter-movement jump refers to the momentum force applied to decelerate the downward counter-motion of the body eccentrically just before the upward or propulsive phase of the jump begins. Conversely, Propulsion Impulse refers to the force applied during the upward or propulsive concentric phase of the motion.
While the net amount of propulsion impulse determines jump height performance and therefore can be improved by focusing on applying a larger force concentrically, this is unlikely to be achieved without effective braking impulse as this provides valuable eccentric loading to the tissues to achieve this.
Therefore, the best jump outcome likely involves some balance or ratio between braking and propulsion impulse. For example, research by Beattie et al 2020 found that World Class Elite sprinters demonstrated higher overall propulsion, but also higher braking impulse, with a propulsion:braking impulse ratio of approximately 1.8. Contrarily Sub-Elite sprinters demonstrated a lower propulsion impulse but a relatively lower braking impulse, equalling a higher propulsion:braking ratio of 2.2.
Braking impulse should also be considered in return to sports examples as often imbalances are very obvious as an athlete re-conditions to the requirements of sudden deceleration in rapid movements such as jumping. Efforts should be made to reduce any imbalances in braking impulse with bilateral CMJ before progressing to more challenging movements such as single-leg jumping, landing or drop jump movements.
References:
Mizuguchi, Satoshi. “Net Impulse and Net Impulse Characteristics in Vertical Jumping.” (2012).
Beattie, Kris & Tawiah-Dodoo, Jonas & Graham-Smith, Philip. (2020). Countermovement Jump Characteristics of World-Class Elite and Sub-Elite Male Sprinters.