Physiological resolution of periodic breath holding during heavy-intensity Fartlek exercise

The purpose was to compare the singular and combined effects of 5 s breath holds (BH) and 5 s sprints, every 30 s, during continuous high-intensity exercise, on ventilation ([Formula: see text]), oxygen uptake ([Formula: see text]O2) and associated kinetics (τ), carbon dioxide production ([Formula: see text]CO2), and arterialized-capillary lactate concentration ([La-]).

Ten men (24 ± 3 years) performed 4-6 min ergometer protocols that included a step-transition from 20 W to a power output of 50% of the difference between lactate threshold and [Formula: see text]O2 peak (Δ50%) including: (1) a continuous protocol (CONT) with free breathing, (2) an intermittent BH protocol (CONT-BH); repeated cycles of 5 s BH: 25 s free breathing, (3) a Fartlek protocol (Fartlek); repeated 5 s at peak aerobic power output: 25 s at Δ50%; (4) combining the 5 s Fartlek and CONT-BH protocol (Fartlek-BH). Breath-by-breath gas exchange, measured by mass spectrometry and turbine, was recorded.

[Formula: see text] E (L min-1) was greater (p < 0.05) than CONT (90 ± 7) in all conditions CONT-BH (98 ± 16), Fartlek (105 ± 10), and Fartlek-BH (101 ± 19). [Formula: see text]O2 and [Formula: see text]CO2 (L min-1) were unchanged in CONT-BH (2.73 ± 0.14 and 3.16 ± 0.38) and greater in Fartlek (2.85 ± 0.12 and 3.43 ± 0.16), compared to CONT (2.71 ± 0.12 and 3.12 ± 0.13). Whereas, [Formula: see text]CO2 during Fartlek-BH was higher (3.28 ± 0.35) and [Formula: see text]O2 was unchanged (2.73 ± 0.14). Fartlek-BH resulted in slower [Formula: see text]O2 kinetics (62.2 ± 19 s) and greater blood lactate concentrations (11.5 ± 2.7 mM), compared to CONT (48.8 ± 12 s; 9.0 ± 2.3 mM, respectively).

It was demonstrated that the CONT-BH resulted in increased ventilation that sustained [Formula: see text]O2. However, [Formula: see text]O2 was restricted when an additional work was combined with the BH condition.