Loss of resting bradycardia with detraining is associated with intrinsic heart rate changes
Braz. j. med. biol. res
;
38(7)July 2005. tab
Artigo
em Inglês
| LILACS
| ID: lil-403870
ABSTRACT
The mechanisms underlying the loss of resting bradycardia with detraining were studied in rats. The relative contribution of autonomic and non-autonomic mechanisms was studied in 26 male Wistar rats (180-220 g) randomly assigned to four groups sedentary (S, N = 6), trained (T, N = 8), detrained for 1 week (D1, N = 6), and detrained for 2 weeks (D2, N = 6). T, D1 and D2 were treadmill trained 5 days/week for 60 min with a gradual increase towards 50 percent peak VO2. After the last training session, D1 and D2 were detrained for 1 and 2 weeks, respectively. The effect of the autonomic nervous system in causing training-induced resting bradycardia and in restoring heart rate (HR) to pre-exercise training level (PET) with detraining was examined indirectly after cardiac muscarinic and adrenergic receptor blockade. T rats significantly increased peak VO2 by 15 or 23.5 percent when compared to PET and S rats, respectively. Detraining reduced peak VO2 in both D1 and D2 rats by 22 percent compared to T rats, indicating loss of aerobic capacity. Resting HR was significantly lower in T and D1 rats than in S rats (313 ± 6.67 and 321 ± 6.01 vs 342 ± 12.2 bpm) and was associated with a significantly decreased intrinsic HR (368 ± 6.1 and 362 ± 7.3 vs 390 ± 8 bpm). Two weeks of detraining reversed the resting HR near PET (335 ± 6.01 bpm) due to an increased intrinsic HR in D2 rats compared with T and D1 rats (376 ± 8.8 bpm). The present study provides the first evidence of intrinsic HR-mediated loss of resting bradycardia with detraining in rats.
Texto completo:
DisponíveL
Índice:
LILACS (Américas)
Assunto principal:
Condicionamento Físico Animal
/
Descanso
/
Sistema Nervoso Autônomo
/
Bradicardia
/
Frequência Cardíaca
Tipo de estudo:
Fatores de risco
Limite:
Animais
Idioma:
Inglês
Revista:
Braz. j. med. biol. res
Assunto da revista:
Biologia
/
Medicina
Ano de publicação:
2005
Tipo de documento:
Artigo
País de afiliação:
Brasil
Instituição/País de afiliação:
Escola de Educação Física e Esporte/BR
/
Universidade de São Paulo/BR
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