The Impact of Additional Respiratory Dead Space Volume Mask During Warm-Up on Skin Blood Flow and Choice Reaction...

Background: This study aimed to assess skin blood flow (SkBF) and choice reaction time (RT) after breathing through an increased respiratory dead space volume, following warm-up and prior to intense exercise. Methods: A group of 24 cyclists completed two exercise tests on a cycle ergometer, each at a workload of 110% of their maximal power (110%Pmax) determined during a graded test. A 15 min warm-up and an 8 min passive recovery period preceded both tests. During the recovery period before one of the tests, participants breathed through an increased respiratory dead space volume (ARDSv) of 1000 mL, while no breathing modification (non-ARDSv) was used before the other test. During the tests, measurements included skin blood flow (SkBF), body surface temperature (T), heart rate variability (HRV) parameters, and choice reaction time (RT). In both experimental protocols, main and mixed effects were detected across five repeated SkBF measurements (taken during the warm-up, the first half of recovery, the second half of recovery, during the 110%Pmax test, and in post-test recovery). Results: The analysis revealed higher HR and lower SDNN values (p < 0.05) during the post-warm-up rest period in the ARDSv protocol compared to the non-ARDSv protocol. The Friedman analysis of variance showed statistically significant effects of repeated measurements of SkBF in the non-ARDSv test (χ² = 52.37; df = 4; p = 0.00; W = 0.55) and in the ARDSv test (χ² = 64.1; df = 4; p = 0.00; W = 0.67). Similar effects were obtained in the T analysis. Post hoc tests showed that SkBF and T at restitution after the 110% Pmax test were statistically significantly higher than SkBF and T during the 110% Pmax test only in the ARDSv protocol. Analysis of variance revealed a repeated-measures effect for mean RT (ƞ² = 0.21; df = 1; p = 0.00; F = 11.97) and covariance analysis showed that baseline mean RT was a strong predictor of outcome mean RT, while the study protocol was a weak predictor of post-exercise mean RT. Conclusions: Higher HR and lower SDNN during the period between warm-up and the 3 min test suggest increased physiological strain associated with the ARDSv procedure. Furthermore, only weak and inconclusive effects were observed for skin blood flow and choice reaction time responses following ARDSv application.