Cardiac acceleration as a marker of vagal withdrawal in heart rate control during exercise in humans.
J Pak Med Assoc
; 53(8): 375-8, 2003 Aug.
Article
em En
| MEDLINE
| ID: mdl-14558748
ABSTRACT
OBJECTIVE:
To investigate whether the time rate of change in heart rate i.e. cardiac acceleration, during aerobic exercise in human subjects could be used to differentiate vagal withdrawal from sympathetic stimulation.METHODS:
Fifteen male subjects exercised on a bicycle ergometer at 50 Watts (Step 1), then 100 Watts (Step 2), for 2 minutes each.RESULTS:
Heart rate (HR) was monitored from a resting value (mean +/- SD) of 80.3 +/- 12.9 to 113.8 +/- 13.6 beats min-1 in Step 1. In Step 2 exercise, HR increased from 113.8 +/- 13.6 to 145 +/- 20 beats min-1. At the initiation of Step 1, a rapid acceleration of HR was observed in the form of an overshoot response. In contrast to Step 1, a small overshoot response of cardiac acceleration was observed during Step 2. The difference between the mean cardiac acceleration at 10 seconds in Steps 1 and 2 was significant (2.40 +/- 0.19 and 0.71 +/- 0.12 beats min-1 sec-1, p<0.0001).CONCLUSION:
The initial vagal withdrawal of exercise-induced tachycardia, as a frontline adaptive mechanism, can be indirectly identified from HR transients using cardiac acceleration as a new marker.
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Base de dados:
MEDLINE
Assunto principal:
Nervo Vago
/
Exercício Físico
/
Frequência Cardíaca
Idioma:
En
Ano de publicação:
2003
Tipo de documento:
Article