Static apnea effect on heart rate and its variability in elite breath-hold divers.
Aviat Space Environ Med
; 79(2): 99-104, 2008 Feb.
Article
em En
| MEDLINE
| ID: mdl-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.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Apneia
/
Mergulho
/
Frequência Cardíaca
/
Hipóxia
Limite:
Adult
/
Humans
/
Male
Idioma:
En
Ano de publicação:
2008
Tipo de documento:
Article