For a long time, I have questioned prescribing balance exercises with eyes closed to athletes in sport. Regular readers of the blog will know that I continuously explore the clinical reasoning behind treatments and interventions but have a particular interest in exercise prescription. I have to admit that single leg balance with eyes closed is an example of exercise prescription that just doesn’t make sense to me, how many athletes close their eyes to perform a sport related task? I’m regularly seeing discussions online about “what is functional?” and most of the debates are based around semantics without much weight behind them but provide a good opportunity for people to have a little disagreement about something. To avoid getting into a debate about “functional” I thought it best to better understand the concepts and demands behind “balance” to see if I can answer the “why” behind balance exercise progressions.
One argument for closing eyes during balance exercises is to remove the visual stimulus and encourage the athlete to challenge vestibular and proprioceptive senses. Remove one thing and make others compensate for this deficit. In a study of track athletes, sway velocity (cm/s) increased two-fold when athletes closed their eyes during a static balance test (here) but the only significant finding in the study was the difference in centre of pressure displacement (cm) between non-dominant and dominant limb across the medial-lateral plane. So, no difference between male and female athletes and no difference between “eyes open” and “eyes closed”.
So how does this explain the increase in sway velocity? The sway velocity is the area covered in both the anterior-posterior and medial-lateral planes of the centre of pressure per second, indicating speed of correction. The fact that the displacement between “eyes open” and “eyes closed” was not meaningful suggests that the demand on the fine motor correction increases. A decent argument to include “eyes closed” in a balance program, if that is the aim.
Static balance in dynamic sports
Compared to dynamic balance tests, static tests do not allow re-positioning of the centre of mass within the base of support, so the athlete becomes more reliant on smaller corrections. Different sporting populations have demonstrated varying abilities in static and dynamic balance skills, with gymnasts outperforming in static balance but soccer players demonstrating better dynamic balance (here).
This may seem obvious given the control on the balance beam vs changing direction to avoid an opponent. But actually, perhaps where the argument becomes more broad and complex.
As with any exercise selection, it needs to be appropriate to the aims of the rehabilitation program and the demands of the sport, taking into consideration open and closed skills and linking these to fixed gaze drills vs dynamic gaze drills.
Have we gazed over “skill”?
In a given skill, experts can recognise which cues are relevant and avoid information overload (Martell & Vickers 2004). Below is a slide from my presentation “3 sets of when?” It explains the concept that following any injury, the athletes ability to perform a given skill returns (temporarily) to novice level.
Take a skill like walking. Immediately after an ankle sprain, your ability to perform that skill at an expert level is decreased. A skill that has taken years to perfect, to become automatic, now becomes a task which requires concentration. Thankfully, the return to expert level doesnt take years (hopefully!) and this is where our exercise selection becomes crucial to optimally load and sufficiently challenge. We can’t presume that the pre-injury skill level is the same post-injury. We should also consider experience of the balance task specifically. I can think of experiences where athletes are standing on one leg on a Bosu throwing a reaction ball at a 45 degree trampoline. “Oh you’re no good at that are you… we need to address your balance”
I’ve digressed slightly from single leg balance with eyes closed… and actually I still haven’t discussed “gaze control”.
Gaze control links specifically to experience of a task. Comparing those skilled at orienteering to non-skilled (here) demonstrated an increased ability of the orienteering folk (what do you call people that go/do orienteering?!) to employ a wide focus of attention and to shift efficiently within a peripheral field. The test very cleverly measured gaze control to flashing images with varying degrees of relevant and irrelevant information. What is interesting from this study was that the control group where physically active and proficient in other sports, but the “skill” advantage lay with the orienteering-iers. [shrugs and thinks “sounds right”].
I did not know that about balance!…
Elite athletes have heightened spatial awareness and processing capabilities vs their non-elite counterparts, where gaze control is cool and calm, with long duration of fixation of specific locations. This results in better body positioning end efficient limb actions (here). What better example than ballet. When comparing professional dancers to controls walking along a thin taped line, it was observed that experienced dancers focus far into space, delivering effortless and accurate movements where as controls looked down and focused on the line, moving with greater speed and less control (here). Dancers shift their neural control from somatosensory inputs and to an increased use of visual feedback, via peripheral fields and focused gaze control. Interestingly, sub-maximal exercise has been shown to increase visual attentional performance (posh words for reaction time) and a decreased time need to zoom focus of attention (here). This is useful for prescription considerations.
This efficiency has been demonstrated in other studies also, where the addition of a 4-week balance training program to Physical Education classes in school resulted in increased CMJ, Squat Jump and Leg Extension Strength (here). A time period that can’t be associated with physiological adaptations to muscles (regardless of time, they did balance exercises!) and even when a balance training program has been compared to a plyometric strength program (here). It is thought that improved centre of pressure is linked to spinal and supraspinal adaptations, due to high inter-muscular activation and co-ordination.
My question for any budding researchers out there… if there is a spinal level involvement here, can we utilise the contralateral limb at the very early stages of injury to improve balance on the injured side?
Finally, I get to my argument… balance is the output. Balance and proprioception are different entities, as are gaze strategies and balance. But they may all be interlinked via “skill.”
In researching this blog, I’ve certainly become more accepting of “eyes closed” as an addition to balance programs. But also think I’ve gained more clarity on appropriate prescriptions and the suitable progressions for individuals.
Perhaps “eyes closed” is not a progression, but a starting point!
Immediately post injury, we are looking to internalise feedback (intrinsic) and focus on local, fine movements. There are plenty of regressions within “eyes closed” balance that we can make the athlete safe from secondary injury. Graded progressions from static to dynamic, trying to keep the demands appropriate to the skill required to return the athlete to “expert”.
From here, our progressions should not be the removal of a visual stimulus, but instead optimising and enhancing gaze control:
- Focus on a stationary target –> moving target
- Head still –> head moving (repeat stationary and moving target progressions within this)
- Static balance –> dynamic balance (repeat progressions above)
Essentially, we progress through from intrinsic cues to extrinsic cues, where gradually the athlete is thinking less and less about the mechanics of balance and more about skill execution and performance. We know that gaze control components improve with sub-maximal exercise, so our ordering of our program can reflect this. It is commonplace for balance exercises to be at the beginning of the program, but if balance is our primary aim for rehabilitation, perhaps it should be later in the schedule.
I don’t think this is too dissimilar to how most people prescribe exercises, but for me at least it has given me a better thought process into the “why” which ultimately should make rehabilitation programming more effective and efficient and therefore more elite.
Yours in sport,