Acute Effects of Using Added Respiratory Dead Space Volume in a Cycling Sprint Interval Exercise Protocol: A Cross-Over Study

Abstract

Background: The aim of the study was to compare acute physiological, biochemical, and perceptual responses during sprint interval exercise (SIE) with breathing through a device increasing added respiratory dead space volume (ARDS_V) and without the device. Methods: The study involved 11 healthy, physically active men (mean maximal oxygen uptake: 52.6 ± 8.2 mL∙kg¹∙min^-1). During four visits to a laboratory with a minimum interval of 72 h, they participated in (1) an incremental test on a cycle ergometer; (2) a familiarization session; (3) and (4) cross-over SIE sessions. SIE consisted of 6 × 10-s all-out bouts with 4-min active recovery. During one of the sessions the participants breathed through a 1200-mL ARDSv (SIE_ARDS). Results: The work performed was significantly higher by 4.4% during SIE_ARDS, with no differences in the fatigue index. The mean respiratory ventilation was significantly higher by 13.2%, and the mean oxygen uptake was higher by 31.3% during SIE_ARDS. Respiratory muscle strength did not change after the two SIE sessions. In SIE_ARDS, the mean pH turned out significantly lower (7.26 vs. 7.29), and the mean HCO₃^- concentration was higher by 7.6%. Average La^- and rating of perceived exertion (RPE) did not differ between the sessions. Conclusions: Using ARDS_V during SIE provokes respiratory acidosis, causes stronger acute physiological responses, and does not increase RPE.

Keywords: added respiratory dead space; blood lactate; cardiorespiratory responses; respiratory acidosis; sprint interval exercise.

Figure 1

Cycling sprint interval exercise (SIE) protocol SIE_STD—standard protocol, SIE_ARDS—protocol with the added respiratory dead space volume.

Figure 2

One of the participants with the added respiratory dead space volume (ARDS_V) device.

Figure 3

Changes in (A) peak power output (PPO), (B) pH values, and (C) carbon dioxide partial pressure (pCO₂) in the subsequent bouts during SIE sessions. Statistically significant difference as compared with the first bout (p < 0.05), # Statistically significant difference as compared with the first bout (p < 0.05), * Statistically significant difference between the SIE protocols.

Figure 4

Changes in maximal inspiratory (A) and expiratory (B) muscle strength before and after the SIE protocols.

Figure 5

The average values of (A) FiO₂, (B) FiCO₂, (C) P_ETCO₂, and (D) ventilation (VE)—two minutes before, during and four minutes after last bout in SIE_STD and SIE_ARDS (27 min total).