Kaiser P, Rössner S, Karlsson J
Int J Sports Med. 1981 Feb;2(1):37-42. doi: 10.1055/s-2008-1034582.
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 VO2max, 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 beta-blockers caused a more marked impairment in the exercising muscles. This effect was more pronounced with the unselective beta-blocker propranolol than with atenolol. One interpretation of our findings is that peripheral sympathetic beta 2-receptors in skeletal muscles may contribute to regulating muscle metabolism.
