Sight is one of the key sensory inputs for maintaining upright posture, regardless of whether a person is playing a sport or standing in line at the grocery store. Visual processing helps a person understand body position alongside the vestibular and somatosensory systems. If we compromise any of these key sensory inputs, the common result is degraded postural control. While aging and injury can reduce the quality of information received by the brain, various training methods can enhance our capacity to process these inputs.
Stroboscopic glasses provide a novel method for challenging vision during postural control training beyond merely closing the eyes. Utilizing this specialized eyewear provides clinicians increased control over the amount of visual feedback available to the client or patient. Visual manipulation options range from mild flickering that briefly interrupts sight to long, highly disruptive periods of occlusion, progressing closer to complete vision loss for eyes closed. The controlled reduction, but not elimination, of vision allows the wearer to still train using activities where some vision is needed, such as catching a ball or responding to other aspects of their environment. However, by reducing the amount of visual information available, greater emphasis is placed on vestibular and somatosensory inputs to understand body position and maintain posture, a process referred to as sensory reweighting.
Sensory reweighting challenges postural control acutely, raising the difficulty of maintaining a balanced position during either static stance or during various movements. As we are pushed to utilize information from the vestibular and somatosensory systems more, and vision less, instability is observed. During static balance, stroboscopic glasses show an increase in sway velocity as the level of occlusion rises. As the brain is forced to rely less on vision, the person becomes increasing unstable in both single and double-leg stances. This effect holds true across multiple studies, but due to the high customization possibilities of the strobe setting, different settings may not produce as strong of an effect between levels of occlusion.
This destabilizing effect can increase the demand for any exercise, from standing balance to sport-related movements. The use of the stroboscopic glasses changes the focus from seeing the result of movement to an internal understanding of body position. While the destabilizing effect is observed in the short term, long-term training with this stimulus has been shown to increase balance and sport-related performance.
Beyond static stance, using stroboscopic glasses during dynamic stability activities extends their utility closer to sport-related movements while perturbing and training the system around sensory reweighting. Acutely, during a forward hop task with mild stroboscopic visual disruption, mediolateral instability has been shown to increase. Similar to static challenges, this acute destabilization effect may lead to chronic adaptations.
When using stroboscopic glasses for training dynamic postural stability, they can help address a potential bias towards visual information during movement. Various conditions can cause an individual to over rely on vision due to injury affecting proprioception, such as ACL tears and chronic ankle instability (CAI). In the case of ACL injury, it has been suggested this biased reweighting may contribute to reinjury. Utilizing stroboscopic glasses to influence sensory reweighting towards a healthier balance may aid in reducing such injury risk. This effect is also seen when using the glasses to train individuals with CAI, resulting in improved landing mechanics. Finally, the sport-specific nature of these training exercises more closely mimics sport demands, as visual information is reduced pertaining to body positioning, simulating time when athletes’ attention is pulled towards strategy or their environment.
Stroboscopic eyewear provides a unique demand to balance and dynamic training in a cost-effective manner across a variety of settings, including general balance and sport-specific applications. Coaches and clinicians can use this technique in training and rehabilitation settings to add another layer of challenge to exercises. In addition to a variety of potential sport performance improvements, stroboscopic glasses allow for critical short-term challenges to stability and long-term training to mitigate injury risk.
Otto Buchholz, PhD, LAT, ATC is an assistant professor in the Department of Wellness and Movement Sciences at Eastern Washington University. His research interests revolve around screening tools for postural control to assess movement quality before and after injury and to better inform the return-to-sport decision-making process.
Nathan Robey, PhD, ATC is an associate professor in the Department of Health and Human Development at Western Washington University. He earned his PhD in sport and exercise science at the University of Northern Colorado while working with Dr. Gary Heise. His primary research interest focuses on the impact of anterior cruciate ligament (ACL) reconstruction on neuromuscular control, with the specific goal of improving rehabilitation and return-to-sport outcomes. He is passionate about enhancing athletic performance while quantifying the mechanics of dynamic and static tasks.
