Deceleration Training Could Greatly Reduce Sports Injuries
Most American football fans have seen something like this before and grimaced: A running back, sprinting at breakneck speed down the field, makes a swift cut to evade a defender. But when all his momentum suddenly shifts, the rapid change in force proves to be more than the ligaments in the knee of his planting leg can bear. They snap, and the player crumbles to the ground with a season-ending injury.
Alistair J. McBurnie, a Sports Science Analyst with Manchester United Football Club and a Post-Graduate Research Student at Nottingham Trent University in the United Kingdom, is undoubtedly more of a traditional football (a.k.a. soccer) fan. But he noticed these same sorts of injuries in a variety of sports when athletes perform "rapid horizontal decelerations – stopping quickly from a sprint, often then rapidly changing directions. In a new paper published to the journal Sports Medicine, McBurnie and a team of sports scientists from the UK put forth a strong case that athletes, trainers, and coaches in a range of sports should consider adopting "deceleration training" as a way to prevent potentially devastating ankle and knee injuries as well to improve stopping and starting performance.
In their article, McBurnie and his colleagues noted the strange paradox that athletes are often heavily trained in sprinting to boost their acceleration and top speed, but they are rarely taught how to stop or change directions safely and efficiently, despite the fact that high-intensity decelerations are performed more often than accelerations in sports like soccer, rugby, and football.
"When performing a sharp change of direction, the mechanical loading observed in horizontal deceleration is typically greater than what is observed during acceleration," they write. "Deceleration actions play a pivotal role when reducing whole-body momentum, particularly when running at high velocities and during the execution of sharp-angled directional changes. However, such actions have been identified as mechanisms that are associated with non-contact ACL injury, due to their propensity to generate high multi-planar knee-joint loading while the foot is planted."
So how can athletes train to lessen the risk of injury?
"Training strategies should look to enhance an athlete’s ability to skillfully dissipate braking loads, develop mechanically robust musculoskeletal structures, and ensure frequent high-intensity horizontal deceleration exposure in order to accustom individuals to the potentially damaging effects of intense decelerations that athletes will frequently perform in competition," McBurnie and his colleagues write.
This includes repeated stop-and-start training using a proper deceleration technique, which involves maintaining a low center of mass, strategically placing one's feet, 'braking' earlier and over multiple foot contacts to distribute loads, and remaining visually aware of one's surroundings to anticipate and prepare for needed body movements.
Another key aspect of deceleration training is "eccentric" weightlifting. Much of weightlifting is focused on concentric movement - like performing a bicep curl, doing a chest press, or standing from a squat. The muscles shorten to exert force. Eccentric movement is the opposite – letting down the dumbbell from a curl, or sitting back down into a squat. The muscles lengthen. If performed in a slow, controlled manner, eccentric motion is highly effective at strengthening muscles and even great at strengthening tendons and ligaments.
McBurnie and his colleagues hope that their article will spur more research on decelerations in sports, ultimately leading to a new training paradigm with the potential to greatly reduce the risk of injury.
Source: McBurnie, A.J., Harper, D.J., Jones, P.A. et al. Deceleration Training in Team Sports: Another Potential ‘Vaccine’ for Sports-Related Injury?. Sports Med (2021). https://doi.org/10.1007/s40279-021-01583-x