Is There Really A Performance-Injury Trade Off

You have probably heard of the performance and injury trade off. As performance goes up, injury risk rises with it. There are some arguments that support that, but it is a little over simplified and used as a bit of a cop out in my opinion. We can do better.

At the moment we have a good understanding of what increases ACL injury risk. Outside or landing scenarios, high speeds and large angle cuts coupled together. Increased running speed increases ground reaction force, which increases joint moments. Large angular changes in direction make these joint moments worse as the athlete moves more out of the sagittal plane and into the frontal and transverse plane. In short, the velocity increases the load placed on tissues and the angle of the cut is the catalyst to our at-risk positions. These positions are well published, and it is a long list. So much so, I think that most coaches give up bothering to get their head around things. The 3D biomechanics literature certainly doesn’t help.

Day to day in training, we have two options to reduce risk: Reduce velocity or reduce the angle the athlete cuts to. But we associate moving slower as a negative impact on performance (I don’t think it always is) and the cutting angle is more non-modifiable. Not completely non-modifiable, but it is further down the scale for sure. Because of the non-modifiable angle, we should be coaching good movement habits and techniques to reduce the chances of risk. But it is worth considering that the situation itself dictates the positions we see during ACL scenarios. More lateral trunk lean, an extended knee position, a heel first contact and a wide lateral plant distance are all related to controlling momentum, producing braking force and moving the body to the direction which the task is demanding. Can we reduce the severity of these positions, sure. At least I think so. It is easy to do a randomised controlled trial, see a difference in post-testing and think that will transfer to competitive performance. But will it?

So yes, coach good technical positions and coordination. But the key here in my opinion is velocity control. While the angle is somewhat out of the athlete’s hands, running velocity isn’t. To reduce load, they either go slower from the outset and moderate their running velocity to optimise adaptability, or they decelerate prior to a cutting task that requires it.

Firstly, we need to make them capable of decelerating. This means both an upgrade in high velocity eccentric strength and the coordination required to utilise it. Once an athlete is better at it, they can then have more load reduction in less time. This helps maintain deception and increases options in different situations? So, as I keep hammering in, making athletes faster with linear running velocities is only one part of the puzzle.

The challenge is that the athlete often has so little time and their need for deception is so high that decelerating isn’t an option. It can make them a sitting duck and give away their intentions to the opposition. Hence why we see lots of speed maintenance regardless if it is coupled with large cutting angles. So they can’t complete the task in front of them without huge risks and they also can’t decelerate as normal or performance suffers. Clearly athletes choose performance over risk reduction.

It is here where the problem is. The task gets attempted, but the athlete tries to deal with deceleration, propulsion and direction change all in one step. Also remember that the ground contact time here is likely to be less than 200ms. What does the body pre-activate for? Deceleration? Propulsion? Lateral force application or anterior? Very difficult to coordinate.

To decelerate there needs to be flexion of both the hip and the knee at the same time to optimally attenuate load (I can’t reference this but genuinely think it is a huge consideration we aren’t looking at). But this takes longer ground contact times and doesn’t go hand in hand with a plant step in cutting. Plus, with the athlete’s intent to explode out of the cut as fast as possible, frequently the hip extends like it wants to be propulsive, but the knee is still dealing with the braking force. This directs load towards the knee and risk increases. Combine this with the earlier mentioned ACL risk factors of the lateral foot plant etc, and we have an at-risk position, with lots of load and a lack of coordination between joints for that load to be dealt with. Cue trunk lean because of the coordination issue and the initial high momentum and we have increased knee abduction moment. Snap.

Making them capable of decelerating was step one. But to avoid the above issues, we should also help them not put themselves in the situation in the first place. The best way to do this is to help them understand their own ability and at what point their running velocity becomes and an issue. The need to have repetitions where they realise exactly what they are and are not capable of. Different approach distances, different angles, pre-planned and reactive etc. All with a desire to help them understand at what velocity they are the most adaptable. The trouble with the idea that ‘the game does this’ is that they usually don’t get the variations they need. And even if they do, their attention is elsewhere. They aren’t focussed on learning and experimenting with velocities, angles and solutions.

If we improve this (velocity control and deceleration capability) they are less likely to be in high risk injury situations in the first place. I would also argue that the increased adaptability will improve performance.

So not so much of a performance injury trade off after all.