Neural control of cardiovascular responses and of ventilation during dynamic exercise in man.

S. Strange, N. H. Secher, J. A. Pawelczyk, J. Karpakka, N. J. Christensen, J. H. Mitchell, B. Saltin

Research output: Contribution to journalArticle

92 Scopus citations

Abstract

1. Nine subjects performed dynamic knee extension by voluntary muscle contractions and by evoked contractions with and without epidural anaesthesia. Four exercise bouts of 10 min each were performed: three of one‐legged knee extension (10, 20 and 30 W) and one of two‐legged knee extension at 2 x 20 W. Epidural anaesthesia was induced with 0.5% bupivacaine or 2% lidocaine. Presence of neural blockade was verified by cutaneous sensory anaesthesia below T8‐T10 and complete paralysis of both legs. 2. Compared to voluntary exercise, control electrically induced exercise resulted in normal or enhanced cardiovascular, metabolic and ventilatory responses. However, during epidural anaesthesia the increase in blood pressure with exercise was abolished. Furthermore, the increases in heart rate, cardiac output and leg blood flow were reduced. In contrast, plasma catecholamines, leg glucose uptake and leg lactate release, arterial carbon dioxide tension and pulmonary ventilation were not affected. Arterial and venous plasma potassium concentrations became elevated but leg potassium release was not increased. 3. The results conform to the idea that a reflex originating in contracting muscle is essential for the normal blood pressure response to dynamic exercise, and that other neural, humoral and haemodynamic mechanisms cannot govern this response. However, control mechanisms other than central command and the exercise pressor reflex can influence heart rate, cardiac output, muscle blood flow and ventilation during dynamic exercise in man.

Original languageEnglish (US)
Pages (from-to)693-704
Number of pages12
JournalThe Journal of Physiology
Volume470
Issue number1
DOIs
StatePublished - Oct 1 1993

ASJC Scopus subject areas

  • Physiology

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    Strange, S., Secher, N. H., Pawelczyk, J. A., Karpakka, J., Christensen, N. J., Mitchell, J. H., & Saltin, B. (1993). Neural control of cardiovascular responses and of ventilation during dynamic exercise in man. The Journal of Physiology, 470(1), 693-704. https://doi.org/10.1113/jphysiol.1993.sp019883