What is Deceleration?
Everyone has heard and understands the concept of deceleration: it’s slowing down. It’s pressing the brakes in your car at a red light or a stop sign in order to come to a stop. If acceleration is pressing the gas pedal to speed up and produce force, then deceleration is pressing the brake to slow down and absorb force. But how does this concept of deceleration apply to sport?
Defined by one group of researchers, “Deceleration refers to the ability to slow down quickly and efficiently from one activity or movement to another, thereby allowing the individual to adjust their momentum and reduce the risk of injury” (Wolfe et al. 2023).
Another definition proposed by Harper et al. is, “a player’s ability to proficiently reduce whole body momentum, within constraints, and in accordance with the specific objectives of the task (i.e., braking force control), while skillfully attenuating and distributing the forces associated with braking (i.e., braking force attenuation)” (Harper et al. 2022).
What do these definitions have in common? The ability of an athlete to slow and control their momentum on a full body scale.
When we talk about a strong baseline in our athletes, we are referring to baseline strength and endurance. Most athletes are aware of these aspects of rehab. But what about deceleration? This is another vital component of an athlete’s baseline that we hone into during rehab.
This week’s blog is going to discuss what deceleration is and why it’s important for athletes returning to sport after an injury. Let’s jump in!
Why is Deceleration an Important Aspect of Rehab?
Last week’s blog talked about what rehab looks like for returning to running after an ACL injury. And while running is a vital component of most sports, rehab cannot and should not stop there. Besides cross country, there are really no sports that require running at the same pace throughout the entire competition. Sports require the ability to run, yes, but typically go a step further to include movements like acceleration, deceleration, cutting, and change of direction.
Did you know that a large majority of non-contact ACL tears actually come from cutting? Yes, you need to be able to accelerate (speed up) as an athlete, but you also have to be able to decelerate (slow down) in order to prevent injury.
Scoring a touchdown? Offense had to sprint fast, slow down (decelerate), then juke around the defense. Layup? Same thing except this time deceleration was followed by a quick acceleration (single leg jump for that lay up). Scoring a goal in soccer? You were likely dribbling at speed then planted your non-shooting foot. That plant foot had to decelerate in order to get the shot off.
The kicker (no pun intended) in all of these scenarios? Most of these decelerations were done on one leg, another reason that single leg training is included in any lower body rehab program.
A recent study analyzed 53 videos of 53 ACL injuries in 7 different sports. What did they discover? “These studies found that in non-contact sports, the three predominant forms of injury mechanism were landing from jumping, decelerating, and cutting maneuvers” (Schick et al. 2023).
Additionally, in assessing these 53 videos, “deceleration was the most common injury maneuver, present in 32 (60%) athletes” (Schick et al. 2023). 32 out of 53 videos had deceleration as the mechanism of injury- a staggering amount!
What’s more? In soccer, high-intensity decelerations occur up to 2.9x more often than high-intensity accelerations. Plus, the load per meter undertaken by the athlete is 65% higher than any other sport required skill, and roughly 37% higher than acceleration (Harper et al. 2018).
The big reasons deceleration has to be trained in rehab? Essentially, deceleration…
Is a leading cause of injury (32 out of 53 videos of ACL tears)
Happens most often in sport (2.9x more than acceleration)
Happens with the most force (65% more than other skills)
So Deceleration is just Stopping?
But deceleration doesn’t stop (literally) there. After deceleration comes the glamorous stuff: the jump, the sprint, the shot, the kick. NSCA notes, “Common to most situations in which deceleration occurs is the need to initiate a propulsive force soon after the deceleration. For example, an athlete may decelerate and then push off to change direction. Simply put, the athlete must reduce force (decelerate) and produce force (accelerate) in some manner, such as changing direction, jumping, tackling, and so on. Performing this task effectively is a key to multidirectional speed and agility.”(NSCA 2017).
Deceleration requires incredible body awareness, strength, and control. It requires an athlete to be strong at different speeds and couple this strength with split second reactions. Very rarely does an athlete just decelerate for the sake of decelerating. Decelerating is typically in preparation of the next, more important movement: decelerating prior to getting over that hurdle, decelerating before taking that shot, decelerating prior to cutting around that defender, or decelerating before jumping up to shoot that 3 pointer.
You get the point. And this drives home the fact that for most athletes, it’s not enough to just “get in the weightroom.” We love the weightroom, but training has to be specific and translate to the demands of an individual’s sport.
This is why we have our athletes do counter movement jumps, multi directional cutting, and “stop and go’s” in all directions and environments during late stage rehab. (More on training deceleration in part 2 of this series).
Let’s be real. Nobody (except maybe our nerdy PTs here at Made 2 Move) watches a professional sports game and says, “DANG look at that deceleration!” No, people pay attention to the fun stuff, the *glamorous* aspects of sport, like the touchdown, slam dunk, or goal. These are what get the glory and bring home the gold.
However, almost all of these glamorous movements require deceleration as a prerequisite. Thus, we preach to our athletes: let’s do the basics (like decelerating) well. THEN, we can get to the glam and glory.
Stay tuned for part 2 of this series on deceleration where we will unpack how to test, train, and monitor deceleration in athletes.
Interested in working with a therapist who will pay attention to all aspects of your sport? Reach out to email@example.com to set up an initial evaluation!