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Int J Sports Med 1981; 02(1): 37-42
DOI: 10.1055/s-2008-1034582
© Georg Thieme Verlag Stuttgart · New York

Effects of β-Adrenergic Blockade on Endurance and Short-Time Performance in Respect to Individual Muscle Fiber Composition*

P. Kaiser, S. Rössner, J. Karlsson
  • Laboratory for Human Performance (FOA 57), National Defence Research Institute and Department of Clinical Physiology, Karolinska Hospital, S-104 01 Stockholm, Sweden
* The study was supported by grants from the Swedish Medical Research Council (No. 4251), the Research Council of the Swedish Sports Federation, and ICI-Pharma Sweden. The authors gratefully acknowledge the assistance of Rickard Schéle with the statistical procedures.
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Publication History

Publication Date:
14 March 2008 (online)

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Abstract

Nine physically active males were studied three times with four different exercise tests after administration of placebo, 0.1 g atenolol, or 0.08 g propranolol in random order. The test modals were: bicycle ergometer exercise at 50% of V̇O2max, peak torque during knee extension, the Wingate muscle power test, and 2000 m track running. Muscle fiber composition had previously been determined. In subjects with a high percentage of slow-twitch fibers the β-blockers caused a more marked impairment in the exercising muscles. This effect was more pronounced with the unselective β-blocker propranolol than with atenolol. One interpretation of our findings is that peripheral sympathetic β2-receptors in skeletal muscles may contribute to regulating muscle metabolism.

Key words

selective and unselective β-adrenergic blockade - muscle fiber types in man - short-term exercise - endurance exercise

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