In 2018 I was driving my 1995 Subaru Legacy to work (RIP old friend) when going down a hill I pressed the brake pedal and it went straight to the floor. I was not slowing down! A hydraulic brake line blew out meaning I had no pressure and couldn’t stop. This isn’t unlike a blown hamstring while trying to decelerate.
There is an emphasis in team sports on accelerations to improve performance and reduce injury risk. While this is all well and good, there is an opportunity to dig deeper into the science and rethink our injury prevention models. High velocity decelerations happen more frequently and produce higher forces than high velocity accelerations in team sports.
While accelerations are more metabolically demanding, decelerations are more mechanically demanding and thus may play a much larger role in injury prevention. To understand this, consider that relative to accelerations, decelerations generate:
- Greater angular velocities
- Increased muscle activation
- Greater hip, knee, and ankle flexion angles
- Increased impact and peak forces
- Higher rate of eccentric force production and loading rates
All this coupled together shows that the mechanical stress of decelerations greatly outweighs that of accelerations. Consider that in soccer, high velocity decelerations occur up to 2.9 times more frequently than high velocity accelerations, we can see that decelerations are a significant factor in mechanical stress and injury risk.
As sports performance professionals we would be wise to implement deceleration training to our comprehensive performance and injury prevention programs. As we know, in order to get an adaptation, we need a stimulus. To strengthen the muscles, ligaments, and tendons of the lower body which play a coordinated role in deceleration, we must make a conscious and purposeful decision to train deceleration.
Much like my old Subaru, if we ignore the mechanical components of stopping, we are in trouble. Take care of those components before you try to stop going down a hill. There is no good place to blow out a hydraulic line or a hamstring, instead, perform the necessary maintenance to avoid an issue. Train decelerations and strengthen your body so you can slow down what you speed up.
And if you’re curious, I safely coasted to a stop at the bottom of the hill. A blown hammy probably won’t have the same ending.
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For those interested, this article was based on the following papers:
“Damaging nature of decelerations: Do we adequately prepare players?” by Damian Harper
“Deceleration Training in Team Sports: Another Potential ‘Vaccine’ for Sports-Related Injury” by McBurnie, A, et al.