Citation

Lemaître F, Buchheit M, Joulia F, Fontanari P, Tourny-Chollet C. Aviat. Space Environ. Med. 2008; 79(2): 99-104.

Affiliation

Centre d'Etudes des Transformations des Activités Physiques et Sportives, Equipe d'Accueil, Faculté des Sciences du Sport et de l'Education Physique de Rouen, Université de Rouen, France. frederic.lemaitre@univ-rouen.fr

Copyright

(Copyright © 2008, Aerospace Medical Association)

DOI

unavailable

PMID

18309906

Abstract

BACKGROUND: The diving response includes cardiovascular adjustments known to decrease oxygen uptake and thus prolong apnea duration. As this diving response is in part characterized by a pronounced decrease in heart rate (HR), it is thought to be vagally mediated. METHODS: In five professional breath-hold divers (BHDs) and five less-trained controls (CTL), we investigated whether the diving response is in fact associated with an increase in the root mean square successive difference of the R-R intervals (RMSSD), a time-domain heart rate variability (HRV) index. HR behavior and arterial oxygen saturation (SaO2) were continuously recorded during one maximal apnea. Short-term changes in SaO2, HR, and RMSSD were calculated over the complete apnea duration. RESULTS: BHDs presented bi-phasic HR kinetics, with two HR decreases (32 +/- 17% and 20 +/- 10% of initial HR). The second HR decrease, which was concomitant to the pronounced SaO2 decrease, was also simultaneous to a marked increase in RMSSD. CTL showed only one HR decrease (50 +/- 10% of initial HR), which appeared before the concomitant SaO2 and RMSSD changes. When all subject data were combined, arterial desaturation was positively correlated with total apnea time (r = 0.87, P < 0.01). CONCLUSION: This study indicates that baroreflex stimulation and hypoxia may be involved in the bi-phasic HR response of BHDs and thus in their longer apnea duration.

Language: en