Effect of Post-Warm-Up Breathing Using Additional Respiratory Dead Space Volume on Exercise Acid-Base Balance

The aim of the presented study was to compare changes in acid-base balance during high-intensity exercise preceded and not preceded by a warm-up that ended with breathing using additional respiratory dead space volume (ARDSv). The study involved 24 cyclists. Each participant completed two 3 min exercise tests performed at 110% of maximal power from a graded exercise test. A standardized warm-up preceded each 3 min test. Between the warm-up and the test was an 8 min passive rest, during which, in one test, participants breathed using ARDSv increased by 1000 mL, in the second test, ARDSv was not used. After the warm-up and after the 3 min test, a sample of arterialized blood was taken to measure changes in hydrogen ion concentration (ΔH+), lactate (ΔLa−), blood gas parameters, and morphological parameters, and changes in plasma volume (ΔPV) were calculated. Additionally, after the 3 min tests, the rating of perceived exertion (RPE) was assessed. It was demonstrated that ΔH+ (20.4 ± 6.3 and 17.5 ± 6.3, respectively; p = 0.016) and ΔPV (−8.25 ± 4.81 and −4.86 ± 5.58, respectively; p = 0.029) were greater in the test not preceded by breathing restrictions compared with the test preceded by breathing using ARDSv. Simultaneously, no significant differences in ΔH+ were found between tests when post-exercise values were corrected for changes in plasma volume. Furthermore, lower RPE was observed after ARDSv use (Z = 1.97, p = 0.048). Breathing using ARDSv between a warm-up and a high-intensity 3 min exercise induces mild respiratory acidosis, limits the exercise-induced increase in H+ concentration and changes in plasma volume, while affecting lower RPE.