On a recent course I was discussing issues of sensory processing, with particular reference to the feet. In alpine skiers, runners and professional footballers, I have encountered athletes who have laced or buckled progressively more tightly, even moving into smaller shoe sizes, in an attempt to enhance sensory feedback from their feet through compression.
Musing on this, one of the participants came to ask me for thoughts on the fact that the majority of players in the professional rugby team that she worked with request secure ankle strapping prior to each game. Was this a cluster of people trying to do the same thing, she wondered, or could it provoke a similar progressive problem if allowed to continue?
I’m glad that I didn’t venture any thoughts on this until hearing another vital piece of information: the training philosophy followed by the team’s strength and conditioning personnel advocates elimination of rotation in the central body. All tasks are done with this goal, even running tasks, during which sagittal plane motion is intensively drilled. The players are trained to keep the thorax and pelvis in a completely consistent relationship at all times, or as close to it as possible.
This vital piece of information goes some way towards explaining the players’ desire for strong ankle strapping. How so?
Despite the fact that humans are essentially rotational creatures, there is still widespread suspicion about rotation and injury risk. This makes no sense, when we have evolved with so many rotational possibilities throughout our bodies. This is not an evolutionary flaw, but in the rehabilitation and training sectors, it is frequently seen as such. In a recent paper which identified an association between higher trunk displacement motions and better agility performance (Edwards et al, 2016), this higher displacement was described as “decreased trunk control”, despite its apparent link to more effective movement performance. This truly illustrates our dysfunctional relationship with trunk motion.
The issue is not one of rotation versus non-rotation. It is one of when, how much and at what level in the kinetic chain rotation is appropriate. This will change depending upon speed, angle of change of direction, and sagittal plane coordination in the lower limb.
The elimination of relative thorax to pelvic rotation is quite common in conditioning programmes, so this team is not alone in its approach. For sure they will be doing their best to prevent injury, however the fundamental first question when designing any training or preventative programme is simple: what does the person have to be able to do to fulfill their functional requirements?
Now rugby is a sport with both movement and anti-movement requirements. A player must be able to withstand high force impacts, requiring a protective, more compressive response from the body to limit potentially injurious high velocity joint displacement. This team’s training programme would most likely support this function. However, today’s player must also be able to run, cut and change direction effectively. These dynamic requirements mean that a range of kinematic combinations must be available, and this rugby team’s current training regimen would actually oppose this.
The ability to rotate the trunk on the pelvis, and the pelvis over the hip is fundamental to the sport of rugby. It’s necessary to pass, to run and to kick the ball of course, but also to control, channel and disperse forces for agility. At speed, thorax rotation, along with effective sagittal plane motion in the lower body, will strongly influence global movement and force management throughout the kinetic chain when cutting. Trunk rotation in the new direction of the travel has been identified as a positive strategy for reducing knee stress when cutting (Frank et al 2013). However, whether trunk rotation in the initial direction of travel is a threat or an asset in cutting depends upon management of the centre of mass.
When centre of mass displacement relative to centre of pressure is high (as demonstrated by lateral movement of the trunk past the foot), additional trunk rotation can certainly amplify valgus stress on the knee by increasing duration of motion in the original direction after foot plant. However, when lateral trunk displacement is minimised, i.e. the trunk position is relatively stacked over the pelvis, trunk rotation can function to disperse excessive lateral force from the body. Pre activation of trunk muscles themselves is not the key to limiting lateral trunk motion though (Jamison et al 2013.) To achieve reduced lateral trunk displacement, the player must be able to drop their centre of gravity quickly and effectively in the sagittal plane, requiring coordinated flexion through the lower limb joints, in particular the hip.
So, to achieve a high velocity or high angle cutting maneuver, you need multiple segments of your kinetic chain available, from the foot all the way up through the trunk. When you eliminate the possibility of trunk rotation you eliminate a large chunk of that kinetic chain, and also increase your energy cost and control requirement in the trunk itself.
Now let’s imagine that the amount of force to be managed by the body is the same, but now you have markedly reduced the number of options through the kinetic chain to manage them. The basic rule of thumb is that the forces have to go somewhere, so let’s consider the possibilities for how this might impact on the remaining available joints.
If the contribution of the central body is effectively taken out of the equation for dissipating or redirecting lateral force, we are left with the ankle, knee and hip to manage the task.
The most vulnerable of these options under lateral stress is the ankle. It is therefore understandable that the rugby players that we are considering feel more secure with greater support in this area – they will be sensing that vulnerability. If the strapping is withdrawn when the condition of trunk motion constraint is still present, there’s a good chance that the team physiotherapist will encounter an increase in ankle injuries. Quite simply it is the easiest place for the forces to go.
However, if we keep the ankle strapping, we remove another degree of freedom from the kinetic chain, and are now down to two remaining choices: the knee or the hip/groin. The knee doesn’t have a lot of options: as a primarily sagittal plane joint, it is at greater risk of traumatic injury if it is forced to absorb or withstand sudden lateral force, either from impact or rapid change of direction. The hip/groin area, with its high mobility possibilities, is at greater risk of overuse injury, as this will be the easiest location with the greatest options to manage such forces.
So to answer my course participant’s question: yes, the consistent strong strapping may progressively compromise normal sensory feedback potential, with players likely to ask for increasing levels of support. This I have certainly observed over the years with a number of athletes. Given the movement constraints imposed upon the players in training, this is most likely an acquired problem in response to increased potential biomechanical stress on the ankle. So no, I wouldn’t withdraw the strapping at this point, for both psychological and biomechanical reasons, lest I invite a proliferation of ankle injuries. Before any change in ankle management can take place, the training approach itself needs to change, and the necessary movement possibilities throughout the kinetic chain recovered and integrated. If this does not happen, the incidence of knee and groin issues may rise instead (as it had in this example).
When a training philosophy fails the basic test of “what does the person need to be able to do”, there’s a fair chance that we’ll either train the functionality out of the athlete, or set them up for potential injury. In rugby, it is tempting to place the highest emphasis on the impact protection element, but if the player loses the ability to manage his or her own dynamic forces, one area of the body might be spared but another exposed.
If we appreciate movement through the lense of force management, and consider the dynamic requirements of the sport, it is possible to see the potential injury implications associated with restricting links within the kinetic chain. Follow the chain and ask: if we constrain a joint, at what point above or below will the force then be amplified?