Cardiorespiratory adaptations induced by aerobic training in middle-aged men: the importance of a decrease in sympathetic stimulation for the contribution of dynamic exercise tachycardia
Braz. j. med. biol. res
; 31(5): 705-12, May 1998. ilus, tab
Article
em En
| LILACS
| ID: lil-212411
Biblioteca responsável:
BR1.1
RESUMO
We investigated the effects of aerobic training on the efferent autonomic control of heart rate (HR) during dynamic exercise in middle-aged men, eight of whom underwent exercise training (T) while the other seven continued their sedentary (S) life style. The training was conducted over 10 months (three 1-h/sessions/week on a field track at 70-85 percent of the peak HR). The contribution of sympathetic and parasympathetic exercise tachycardia was determined in terms of differences in the time constant effects on the HR response obtained using a discontinuous protocol (4-min tests at 25,50,100 and 125 watts on a cycle ergometer), and a continuous protocol (25 watts/min until exhaustion allowed the quantification of the parameters (anaerobic threshold, VO2,AT; peak O2 uptake, VO2 peak; power peak) that reflect oxygen transport. The results obtained for the S and the T groups were 1) a smaller resting HR in T (66 beats/min) when compared to S (84 beats/min); 2) during exercise, a small increase in the fast tachycardia (delta0-10 s) related to vagal withdrawal (P<0.05, only at 25 watts) was observed in T at all powers; at middle and higher powers a significant decrease (P<0.05 at 50, 100 and 125 watts) in the slow tachycardia (delta1-4 min) related to a sympathetic-dependent mechanism was observed in T; 3) VO2AT (S=1.06 and T=1.33 l/min) and VO2 peak (S=1.97 and T=2.37 l/min) were higher in T (P<0.05). These results demonstrate that aerobic training can induce significant physiological adaptations in middle-aged men, mainly expressed as a decrease in the sympathetic effects on heart rate associated with an increase in oxygen transport during dynamic exercise.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
LILACS
Assunto principal:
Sistema Nervoso Simpático
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Adaptação Fisiológica
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Exercício Físico
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Esforço Físico
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Frequência Cardíaca
Limite:
Humans
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Male
Idioma:
En
Revista:
Braz. j. med. biol. res
Assunto da revista:
BIOLOGIA
/
MEDICINA
Ano de publicação:
1998
Tipo de documento:
Article
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Project document
País de publicação:
Brasil