Prolonged ischaemia impairs muscle blood flow and oxygen uptake dynamics during subsequent heavy exercise.
J Physiol
; 588(Pt 19): 3785-97, 2010 Oct 01.
Article
em En
| MEDLINE
| ID: mdl-20679356
ABSTRACT
Muscle oxygen uptake ( ËVO2,mus) dynamics at the onset of exercise can be affected by prior heavy exercise.We tested the hypothesis that elevated forearm blood flow (FBF) following prior circulatory occlusion would also be associated with accelerated ËVO2,mus dynamics during subsequent heavy hand-grip exercise. Ten trained young men performed 5 min of heavy hand-grip exercise at 30% MVC as a control (CON), and four additional heavy bouts after brief recovery from (1) prior heavy exercise (Heavy A), (2) heavy exercise followed by 2 min occlusion (Heavy B), (3) 15 min occlusion (Heavy C), and (4) 5 min occlusion with 1 min of moderate exercise during occlusion (Heavy D). FBF was measured by ultrasound and arterial venous oxygen content difference was calculated from venous blood samples to estimate ËVO2,mus. FBF and ËVO2,mus dynamics were quantified from the rise time. All priming conditions elevated FBF immediately before the start of subsequent heavy bout (Heavy A 207.4 ±92.8, B 207.8±75.8, C 135.8±59.2, D 199.5±59.0 vs. CON 57.4±16.6mlmin−1, P <0.01). Unexpectedly, prior occlusion reduced FBF and O2 extraction at the onset of subsequent heavy exercise and consequently slowed ËVO2,mus dynamics (Heavy C rise time=95.9±28.9 vs. CON 58.6±14.3 s, P <0.01). FBF and ËVO2,mus dynamics were faster in Heavy A, B and D compared to CON (P <0.05). Overall, there was a positive correlation between the rise times for ËVO2,mus and FBF (r² =0.75) indicating that ËVO2,mus dynamics during heavy forearm exercise are linked to O2 delivery in trained young men. To investigate a possible mechanism for slower adaptation of ËVO2,mus following ischaemia, the prior occlusion condition was repeated after ingesting a high dose of ibuprofen. This resulted in restoration of the FBF and ËVO2,mus to control levels suggesting that a prostaglandin-mediated mechanism after occlusion retarded the adaptation of blood flow and oxygen consumption at the onset of subsequent heavy exercise.
Texto completo:
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Base de dados:
MEDLINE
Assunto principal:
Consumo de Oxigênio
/
Exercício Físico
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Músculo Esquelético
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Isquemia
Tipo de estudo:
Prognostic_studies
Limite:
Adult
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Humans
/
Male
Idioma:
En
Ano de publicação:
2010
Tipo de documento:
Article