Postural reeducation and oral device interaction in rhythmic gymnasts: effects of byte use on stiffness-related performance and low back pain perception

This randomized controlled trial investigated the effects of combining Global Postural Therapy (GPT) with a customized intraoral device (Byte) on stiffness-related performance and perceived stiffness in elite rhythmic gymnasts with low back pain. Seventeen athletes were randomly assigned to a Byte group (n = 8) or a control No Byte group receiving GPT alone (n = 9). Both groups completed a 12-week supervised postural re-education program focused on global muscle chain stretching, spinal alignment, and neuromuscular control. Functional stiffness was assessed across four post-intervention sessions using a Baiobit sensor to measure jump performance variables (maximum speed, height, force, concentric and eccentric phases, flight, and contact time), while perceived stiffness was evaluated using a visual analogue scale (VAS). Both groups improved in maximum speed, height, and force (η² = 0.25-0.31; p < 0.05), with no significant group × time interaction (p > 0.05). A significant reduction in perceived stiffness was observed in the Byte group compared with controls (p = 0.015; η² = 0.35). These findings suggest that adding a customized intraoral device to GPT did not produce additional improvements in objective stiffness-related performance over 12 weeks. However, the Byte group showed descriptively lower subjective stiffness values, which may indicate a potential perceptual effect associated with the device. Further research is required to clarify the clinical relevance and underlying mechanisms of these findings.