Acute and chronic application of novel incremental breath-hold technique increases endurance exercise performance in healthy men and male military personnel.

We evaluated acute (Study A) and chronic (Study B) effects of a novel breath-hold technique (BHT) protocol on performance in military personnel. In Study A, 11 healthy male participants completed either rest or a 40-min BHT before 15 min steady-state (SS) cycling at 80% V̇O2max and a 5-min time trial (TT). BHT acutely increased V̇O2 (200.3%, p = 0.005), produced a significant rise in hemoglobin (Hb; 3%, p = 0.030), and altered end-tidal oxygen (ETO2; 2.99%, p = 0.054), and lower end-tidal carbon dioxide (ETCO2; 12.1%, p = 0.065), reflecting changes in pulmonary gas exchange following breath-hold exposure, during rest. During SS, blood lactate was lower with BHT (-12.2%, p = 0.051; subsample n = 3). TT work was greater after BHT (84.4 ± 12.8 kJ vs. 78 ± 13.4 kJ; p = 0.019). In Study B, 48 United States Marine Corps Officer Candidates completed 3 weeks of BHT during training, with performance assessed via 3-mile run time. Run performance improved in both groups (BHT 7.2%; CON 4.9%). Hb concentration increased in BHT (4.3%; p = 0.037), but declined in CON (-6.6%). Pre-test arterial oxygen saturation (SPO2) was higher in BHT (97.7% ± 0.9% vs. 96.9% ± 1.6%; p = 0.03), while estimated partial pressures of arterial oxygen (PaO2) and carbon dioxide (PaCO2), used as indices of systemic gas exchange status, were similar between groups. These findings suggest that acute responses to BHT may translate into adaptations when repeated, supporting BHT as an adjunct to endurance training and warranting larger, mechanistic trials.