Background: The interaction of group III/IV afferents and chemoreflex during exercise is critical in healthy adults during high altitude exercise or in clinical populations who experience hypoxia. Purpose: Investigate the cardiorespiratory response to simultaneous vascular occlusion (to activate group III/IV afferents) and hypoxia (to activate chemoreflex) during cycling exercise. Methods: 18 adults (9 women, 25 ± 5 years) attended two sessions. Session 1: maximal cycle ergometry test. Session 2: two 26-minute bouts (randomized between hypoxia, 12.5% FiO2 and normoxia, 21% FiO2). Participants cycled at 30% of peak workload for 3 minutes (control, CTL) followed by alternating 2 minute periods of bilateral vascular occlusion of the proximal thigh at pressures of 20, 40, 60, 80, 100 mm Hg in a randomized sequence. Results: Ventilation (VE) increased from CTL to 100 mm Hg during hypoxia (39 ± 9 to 51 ± 16 L/min) and normoxia (31 ± 7 to 39 ± 9 L/min, P < 0.01). Respiratory rate increased with vascular occlusion (P < 0.05) but not hypoxia (P = 0.10). Tidal volume was greater during hypoxia (P < 0.05), with no influence of vascular occlusion (P = 0.40). Mean arterial pressure and heart rate increased more with hypoxia compared with normoxia (P < 0.05). Conclusions: Our findings suggest that vascular occlusion and hypoxia both increase VE, albeit via different mechanisms. While hypoxia increased tidal volume, vascular occlusion increased respiratory rate.
|Original language||English (US)|
|Number of pages||9|
|Journal||Translational Sports Medicine|
|State||Published - Mar 2019|
Bibliographical noteFunding Information:
This work was supported by: National Center for Advancing Translational Science (NCATS) grant KL2TR000136 (TPO), NIH grants HL126638 (TPO), HL71478 (BDJ) and MLKR was supported by a NIH/NIAMS T32AR56950 grant.
© 2018 John Wiley & Sons Ltd
- circulatory occlusion
- group III and IV muscle afferents
- ventilation and blood pressure