Mandibular repositioning effects on running until exhaustion at moderate intensity.

Background: Wearing a mandibular repositioning dental splint may enhance ventilatory function and exercise performance. We aim to analyze the performance and the biophysical effects of wearing an intraoral splint with mandibular repositioning when running until exhaustion at moderate intensity.

Methods: Sixteen trained male runners completed a crossover randomized controlled study to evaluate the effects of two intraoral splints (with and without mandibular forward repositioning) on performance, ventilatory and bioenergetic profiles during running until exhaustion at the velocity corresponding to the anaerobic threshold. Ventilatory variables were analyzed at different running time-points, and a paired samples t-test was employed to compare the experimental conditions across all evaluated variables.

Results: The splint with mandibular forward repositioning facilitated ~12% longer running than the splint without mandibular repositioning. Oxygen uptake was the sole ventilatory variable demonstrating a higher value across all the analyzed running time-points when the mandible was advanced (10^th min, 58.1±9.4 vs. 55.3±9.8; 10 min before the end, 57.7±8.7 vs. 55.3±9.1; and at the end of the exercise, 57.2±8.2 vs. 54.2±9.0 mL∙kg^-1∙min^-1; P≤0.05). The splint with mandibular forward repositioning also elicited a lower rate of perceived exertion (17.1±0.77 vs. 17.4±0.63, P=0.05) and higher aerobic contribution (2611±708 vs. 2212±640 kJ), overall energy spent (2633±708 vs. 2232±642 kJ) and exercise energy cost (0.28±0.05 vs. 0.26±0.05 kJ∙m-1, P≤0.005).

Conclusions: The mandibular forward repositioning elicited a marked improvement in moderate intensity performance, with beneficial physiological and perceived effects.