Rehabbing teenagers can be awkward! – sensorimotor function during adolescence

There is a bit of a buzz phrase in rehab about “individualising programs” and while it is something we wholeheartedly agree with, it is a phrase that is very easy to say and yet very difficult to implement. Especially when you work with a population where said individual changes rapidly through time, like a teenager! It is a common sight on a training pitch to see a star player in their age group suddenly tripping over cones or developing a heavy touch where there was previously effortless control. Side effects of the adolescent growth spurt, where the brain is now controlling a much longer lever. It’s like giving a champion gardener a new set of garden sheers when for the past year they have used little hand-held scissors and asking to them maintain their award-winning standards. (My garden embarrassingly needs some attention and it’s affecting my analogies).

Master-Gardener-Pruner-Secateurs-Shears-Garden-Hand-plants-Shears-trim-cutter-easy-carry-Garden-Tool
The control and precision between these two instruments is influenced by the lever length of the handles…
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…Similar to a rapidly growing femur and tibia which is still being operated by muscles that have length and strength suitable for shorter levers.

 

 

 

 

 

 

 

 

Alongside the performance related issues, there is suggestion that this period of growth may coincide with increased risk of injury (Caine et al 2008). We believe that bone grows quicker than soft tissue, so we are asking a neuromuscular system to control a new, longer lever using prior proprioceptive wiring. Imagine our gardener again, for a long time he has been able to keep his pair of scissors close and controlled, now with his extra long shears the load is further away from his body, his back and shoulders are starting to ache. Not sure what I mean? With one hand hold a pencil to the tip of your nose. Now, with one hand hold a broom handle to your nose. The longer lever is harder to control. **I promise it gets a bit more sciencey than gardening and broom handles. **

Managing these growth spurts is something we have talked about before and recently contributed to a BJSM podcast on the topic (Part 1 & Part 2) and a complimentary BJSM blog about “biobanding” during periods of growth and development (here). This particular blog was inspired by a recent (2015) systematic review looking into exactly which sensorimotor mechanisms are mature or immature at the time of adolescence by Catherine Quatman-Yates and colleagues over in Cincinnati (here). The following is a combination of their summary and our examples of how these findings can influence our rehab programs.

Tailoring the program:

We have so many options for exercise programs, that’s what makes the task of designing them so fun. It challenges our creativity. When working with a teenager with sensorimotor function deficits, let’s call them “Motor Morons” for short, we don’t have to totally re-think our exercise list, just perhaps the way we deliver them. We previously spoke about motor control and motor learning (here) and how our instructions can progress just as our exercises do, but the following relates to children and adolescents in particular.

Consider the stimuli.

Children aged between 14-16 have well-developed visual perception of static objects however their perception of moving objects and visual cues for postural control continue to mature through adolescence. When very young children learn new skills such as standing and walking, they become heavily reliant on visual cues. Quatman-Yates et al suggest that puberty and growth spurts (think gardener with new shears) brings new postural challenges that causes adolescents to regress proprioceptive feedback and increase reliance on visual cues again. From a rehab perspective, we need to consider this as part of our balance and proprioception program. How many of us default to a single leg stand and throwing a tennis ball back & forth from therapist to athlete? For our Motor Moron, this may not be an optimal form of treatment in early stages, where it is commonly used, however it may incredibly beneficial to that athlete in the later stages or as part of ongoing rehab as we try to develop that dynamic perception.

Consider the amount of stimuli involved in an exercise versus what your goal of that exercise is

We should also consider the amount of stimuli we add to an exercise. Postural stability in children is believed to be affected by multiple sensory cues. If we consider that children are more dependent on visual cues than adults are, perhaps our delivery of external stimuli should be tailored also. With a multi directional running drill for example, there is sometimes an element where the athlete is given a decision making task (a red cone in one direction and a yellow cone in another) and they have to react quickly to instructions from the therapist or coach. Rather than shouting instructions like “red cone”, “yellow cone” etc, hold up the coloured cone for the corresponding drill. This way we are utilising this developed visual perception, minimising the number of stimuli and also encouraging the athlete to get their head up and look around rather than looking at their feet.

When to include unilateral exercises:

Within adult populations, it is often considered gold standard to make exercises unilateral as soon as tolerable. If they can deep squat pain free and fully weight bear through the affected side, progress them to pistol squats ASAP, or single leg knee drives. However, young children (pre-pubescent) may struggle with this for a couple of reasons.

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Difficult enough even for an adult to perform, but uncoupling the actions of the each leg & fine muscle movements to maintain balance are extra challenging for children

Firstly, we need to consider postural adjustments. Where as adults and young adults can adjust their balance with smooth control and multiple, small oscillations, children rely on larger ballistic adjustments. There is also reduced anterior-posterior control in younger athletes which suggests reduced intrinsic ankle control. Put this alongside immature structures and (if working a physio, most probably) an injury then single leg exercise become a progression that may be further down the line than an adult counterpart with the same injury. Instead, consider semi-stable exercises. Support the contralateral leg with a football or a bosu ball – something that is difficult to fixate through but provides enough stability to support the standing leg.

Secondly, we understand that coupled movements are mastered earlier in adolescence, around 12-15 years old but uncoupled movement patterns take longer to develop, 15-18 years old (Largo et al). A good example is watching a young child reach for a full cup of water at the dinner table. It is much easier and more natural for them to reach with both hands than it is with one, as coupled movements are unintended. Rarely do you see a child taking a drink with one hand filling their fork with the other – yet this is something commonly seen with adults as they are able to uncouple and segmentalise. Another example is watching a child dynamically turn, watch how the head, trunk and limbs all turn as a “block”, it is not until further down the line where dynamic movements become more fluid. The argument here is that surely running is an uncoupled movement? Or kicking a football, swinging a tennis racket, pirouetting in ballet – they are all uncoupled, segmental movement patterns that we expect kids to do, and in all they cope with. Correct, but it is usually in rehab programs for kids that we begin to introduce unfamiliar tasks and exercises that they may not have encountered before. Also, we should respect the impact of the injury on proprioception and control. So these are all considerations for starting points in exercise & if a regression is ever required.

For this reason, it is important that exercises are monitored and reviewed regularly. There is no need to hold an athlete back because of their age and making assumptions on motor function because of their age. If they can cope, then progress them. But be mindful of “over-control” where speed and variability of movement are sacrificed in place of accuracy and control (Quatman-Yates et al 2015).

Become a Motor Moron hunter

It is worth spending some time watching training, watching warm ups, watching gym sessions and talking with coaches and S&C’s trying to identify a Motor Moron as soon as possible. It’s important to minimise the chances of an immature sensorimotor mechanism ever meeting a growth spurt. It is when these two things combine that we see kids doing immaculate Mr Bean impressions and therefore increase their risk of injury.Safari-kids

Regularly re-assess your exercise programs. If things arent quite progressing as quickly as they should, it may not be failed healing of an injury, but it may be that we are providing the sensorimotor mechanism with too much information!

 

Yours in sport,

Sam

 

“The Young Athlete” conference 9-10th Oct, Brighton. Here

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