Effects of Oral, Oronasal, and Oronasal Breathing with a Decongested Nose During Incremental Maximal Exercise Testing of Well-Trained Endurance Athletes: A Randomized Cross-over Study

Joel Bergqvist^1,2*Fride Uthaug Reite^3,4Fredrik Edin⁵Linus Schiöler⁶Mats Börjesson^7,8Sverre Steinsvåg⁹Stefan Pettersson⁵Johan Hellgren^10,11

• ¹Department of Respiratory Medicine and Allergology, Sahlgrenska University Hospital, Gothenburg, Sweden
• ²Centre for Sleep and Wake Disorders, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
• ³Department Of Otolaryngology, Head and Neck Surgery, Sørlandet Hospital, Kristiansand, Norway
• ⁴Norsk Hydro AS, Karmøy, Norway
• ⁵Centre for Health and Performance, Department of Food and Nutrition, and Sport Science, University of Gothenburg, Gothenburg, Sweden
• ⁶Occupational and Environmental Medicine, School of Public Health and Community Medicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
• ⁷Department of Molecular and Clinical Medicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
• ⁸Center for lifestyle Intervention, Department of MGAÖ, Östra Hospital, Gothenburg, Sweden
• ⁹Department Of Otolaryngology, Head and Neck Surgery, Sørlandet Hospital and Haukeland University Hospital, University of Bergen, Bergen, Norway
• ¹⁰Department of Otorhinolaryngology, Head & Neck Surgery, Sahlgrenska University Hospital, Region Västra Götaland, Gothenburg, Sweden
• ¹¹Institute of Clinical Sciences, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden

Introduction: Nasal breathing is preferable for persons at rest and remains partially active during oronasal breathing in exercise. However, its potential contribution to performanceparticularly in cases with a decongested nose -remains understudied in well-trained athletes.This study investigates whether nasal airflow during oronasal breathing influences performance in well-trained, endurance athletes. Specifically, we examine whether nasal decongestion enhances ventilatory efficiency and, thereby, improves time-to-exhaustion (TTE), maximal oxygen uptake (V ̇O2max), and maximum power output (Wmax), as compared to oral-only breathing.Methods: Twelve male, well-trained cyclists/triathlon athletes (mean V ̇O2max, 67.2 ± 5.5 ml•kg⁻¹•min⁻¹) with age range of 30.6 ± 8.7 years, were included. Two characterization tests were performed: 1) an incremental cycle test to determine V ̇O2max and Wmax; and 2) a familiarization trial of the experimental exercise protocol. The three experimental exercise trials consisted of five 6-minute submaximal steady-state levels (50 W and 100 W at 50 rpm for the first two stages, followed by 40%, 58%, and 75% of the individual Wmax at 80 rpm), concluding with a TTE test.Results: There were no significant differences between the three breathing modes (p > 0.05) in terms of the cardiopulmonary or performance parameters, including the rate of perceived exertion, respiratory frequency, mean minute ventilation, V ̇O2max, and Wmax. Although not statistically significant (p > 0.05) TTE was 2.8% and 4.2% longer during oronasal and decongested oronasal breathing, respectively, as compared to oral-only breathing. The mean capillary blood lactate level was significantly (p < 0.05) lower immediately after and 3 minutes after the TTE test in the oral-only breathing condition (9.12 ± 2.20 mmol/L), as compared with the oronasal (9.83 ± 2.19 mmol/L, Cohen's d = 0.43) and decongested-nose (9.81 ± 2.29 mmol/L, d = 0.41) conditions.Oral-only breathing is associated with a non-significant shorter TTE than oronasal breathing with or without nasal decongestion, although it results in significantly lower mean capillary blood lactate levels following maximal aerobic exercise. These findings suggest that a single, low-resistance oral breathing route reduces lactate accumulation under maximal effort, whereas oronasal breathing -particularly in the presence of nasal decongestion -may be more beneficial for sustaining endurance.