Effects of SVT on Balance and Proprioception

Plain-language summary

This study was conducted to scientifically investigate the effects of a training program utilizing stroboscopic glasses on balance and proprioceptive performance in adolescent male volleyball players. A quantitative research approach was adopted, and a pre-test-post-test experimental design with a control group was employed to rigorously examine the cause-effect relationships between variables. The study sample consisted of 30 adolescent male volleyball players aged between 12 and 18 years. Inclusion criteria required participants to have been licensed volleyball players for at least one year and to be regularly engaged in training sessions at least twice per week. To ensure objectivity, participants were randomly assigned, using a computer-based randomization method, into an experimental group (n = 15) and a control group (n = 15). The experimental intervention lasted six weeks and was specifically designed to complement volleyball-specific technical training. Both groups participated in training sessions twice per week, at the same time of day and with identical training volumes. Within the stroboscopic visual stimulus protocol, athletes in the experimental group used stroboscopic glasses continuously for a total of 2.5 minutes during each training session. This 150-second exposure was determined to encourage athletes to rely more heavily on proprioceptive and vestibular mechanisms under conditions of reduced visual input. The glasses, equipped with LED-filtered lenses that alternated between transparent and opaque states at specific frequencies, manipulated the transmission of visual information to the central nervous system, thereby forcing athletes to maintain motor control with limited visual input. In contrast, the control group completed the same 2.5-minute segment and the entire training protocol under normal visual conditions, without any visual restriction. All training sessions were conducted in an indoor sports facility under the supervision of an experienced coach, ensuring a controlled environment free from external disturbances. Athletes' fatigue levels, adherence to the protocol, and overall health status were monitored on a session-by-session basis. Following the completion of the six-week intervention, both groups underwent post-intervention assessments to determine the effects of the training program on performance parameters. Dynamic balance performance was evaluated using the Y Balance Test, a widely accepted and validated assessment tool in the literature. During testing, participants performed barefoot while maintaining single-leg stance on the dominant limb and reaching as far as possible with the contralateral limb in the anterior, posteromedial, and posterolateral directions. The best score from three trials in each direction was recorded. All reach distances were normalized to limb length to minimize the influence of anthropometric differences. Proprioception was assessed through joint position sense and movement perception tests. During these assessments, participants' vision was occluded to eliminate visual input and isolate somatosensory function. The extremity was passively positioned at predetermined target angles by the researcher, and participants were then asked to actively reproduce the same position. The absolute angular difference between the target and reproduced positions was measured in degrees using a goniometer and recorded as the "proprioceptive error score." Data collection was completed in two phases: baseline measurements conducted prior to the intervention (pre-test) and follow-up measurements performed after the six-week training program (post-test). The findings of this study indicate that conventional volleyball training significantly improves both static and dynamic balance performance. However, stroboscopic visual training appears to produce more pronounced and selective improvements in proprioceptive awareness. These results suggest that, rather than directly enhancing overall performance outcomes, stroboscopic training may serve as an effective tool for targeting sensory-motor subcomponents that underpin athletic performance.

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