Effect of Stroboscopic Balance Training on Chronic Ankle Instability in Volleyball Players

Ankle sprains are among the most common injuries in both athletes and the general population. A large-scale systematic review reported that ankle sprains account for approximately 80% of injuries occurring among athletes in most sports. Among volleyball players, ankle sprains are the most prevalent injury, constituting about 41% of all volleyball-related injuries. In athletes, performing certain technical or sport-specific tasks that require attention, such as running, sudden changes of direction, or landing, is associated with an increased risk of ankle sprain. Approximately 20% of acute ankle sprains progress to chronic conditions. Chronic ankle sprains lead to serious proprioceptive dysfunctions, including deficits in joint position sense and delayed peroneal muscle reaction time, resulting in significant ankle instability and balance impairment. Balance training in individuals with chronic ankle instability is concerned with improving postural control and has been recognized as an effective therapeutic approach for this population. Although there is evidence supporting the effectiveness of balance training in improving sensorimotor deficits in individuals with chronic ankle instability, including static and dynamic postural stability, muscle strength, and reinjury rates, reliance on visual information remains unchanged after conventional rehabilitation. The inability of visual input to utilize somatosensory feedback from the ankle joint has been identified as a factor contributing to recurrent ankle sprains in these individuals. Conventional interventions for chronic ankle instability do not address the need to correct altered somatosensory deficits following an ankle sprain. Therefore, a specific treatment option focusing on this neurophysiological dysfunction would be beneficial for these patients. Kim et al. reported the effect of stroboscopic vision in reactivating visual input in individuals with chronic ankle instability. Stroboscopic vision involves the use of special glasses in which the lenses alternate between transparent and opaque at intervals of 100 milliseconds, thereby reducing visual feedback. Balance training with stroboscopic glasses offers a different approach compared to conventional balance training. Stroboscopic balance training is a technique aimed at manipulating visual perception. In this method, the stroboscopic glasses intermittently block light, affecting the brain's processing of visual information. Consequently, the brain must process seen objects less continuously and less clearly. Stroboscopic glasses make rapid movements and changing situations more difficult to perceive, thereby challenging the balance system further. Conventional balance training, on the other hand, involves methods used to improve static and dynamic balance skills. This training approach aims to strengthen the balance mechanism through the use of specialized balance devices, exercises, and techniques. For example, balance boards, balance pads, trampolines, and various movement exercises are commonly used tools in conventional balance training. This method works on factors such as muscle strength, postural control, and coordination to improve static and dynamic balance control. The main difference between balance training with stroboscopic glasses and conventional balance training is the use of glasses that manipulate visual perception. These glasses challenge the brain's processing, thereby providing greater stimulation to the balance mechanism. In contrast, conventional balance training uses general exercises and tools to improve balance skills and does not focus on altering visual perception. Stroboscopic glasses have previously been used to improve sports performance in baseball players with positive results. They have also been incorporated into rehabilitation programs for individuals with chronic ankle instability, demonstrating beneficial outcomes. Although chronic ankle instability is a common problem among volleyball players, to our knowledge, no study has investigated a rehabilitation program using stroboscopic balance training in female volleyball players with chronic ankle instability.

Inclusion criteria

• Were professional female volleyball players.
• Had a history of at least two episodes of pain and swelling in the same ankle.
• Experienced at least one ankle sprain within the last six months.
• Exhibited persistent symptoms during functional activities and were free from symptoms related to any previous lower-extremity injuries.
• Reported a feeling of instability in the ankle joint.
• Had no other lower-extremity musculoskeletal injuries in the past six months.

Exclusion criteria

• Reported any vestibular or balance-related dysfunction.
• Had any systemic disease.
• Experienced an acute ankle sprain within the past six weeks.
• Had a history of fractures in the lower extremities.