The latest findings on the ergogenic effects of a dentistry-design, bite-aligning mouthpiece require additional research to assess its impact on anaerobic ability and ventilatory parameters. This paper was aimed at determining the ergogenic acute effects of wearing a custom-made mouthpiece on oral airflow dynamics, 30-s Wingate Anaerobic Test performance parameters. Twenty-eight healthy and physically-active male subjects (age: 24.50 ± 3.32, height: 181.34 ± 7.4, weight: 78.14 ± 8.21), were voluntarily studied. The subjects were first briefed on the test protocols, and then performed the 30s Wingate test and Spirometer test. The experimental trials were performed in a random counterbalanced order. We evaluate maximum expiratory volume (VEmax L min-1), mean power (W kg-1), peak power (W kg-1), time to peak (s), rate to fatigue (W s-1) and lactate production (mMol L-1), rate of perceived exertion (RPE). There were significant differences between mouthguard and no-mouthguard conditions in mean power (W kg-1), peak power (W kg-1), time to peak (s), and rate to fatigue (W s-1) for the 30-s Wingate Anaerobic Test. Significantly lower lactate production (mMol L-1) was observed, in mouthguard condition but no significant differences were found in RPE. In airflow dynamics, the VEmax L min-1 was significantly higher when comparing the mouthguard and the no mouthguard conditions in both forced and unforced conditions. In conclusion, wearing a customized mouthguard improves anaerobic ability and increases forced expiratory volume. This study will help practitioners improve athlete's performance in anaerobic activities where high intensity action might provoke jaw-clenching, contributing in reductions of lactate and fatigue, and improving ventilatory parameters.