['Research is equivocal regarding endurance performance benefits of external nasal dilators, and currently research focusing on internal nasal dilators is non-existent. Both devices are used within competitive cycling. This study examined the influence of external and internal nasal dilation on cycling economy of motion and 20-km time trial performance.', 'The study utilized a randomized, counterbalanced cross-over design.', 'Fifteen trained cyclists completed three exercise sessions consisting of a 15min standardized warm up and 20-km cycling time trial while wearing either a Breathe Right', 'No differences were observed for mean 20-km power output between the internal (270±45W) or external dilator (271±44W) and control (272±44W). No differences in the economy of motion were observed throughout the 15-min warm up between conditions.'] Does neither internal nor external nasal dilation improve cycling 20-km time trial performance?