Abstract

The aim of the present study was to describe possible changes in the IEMG activity and the EMG frequency spectrum of the exercising muscle as a result of acute beta-blockade. Continuous cycle exercise was performed on an electrically braked ergometer at a pedalling frequency of 60 rpm and with 30 W increments every fourth minute from an initial load of 90 W to a final load of 240 W corresponding to 73-96 (individual range) of maximal oxygen. Plasma drug concentration averaged 41 +/- 27 ng/ml. Heart rate at 240 W averaged 170 +/- 11 and 130 +/- 9 bpm in control and betablockade experiments. Blood lactate concentration was higher during beta-blockade as compared control experiments only at the highest work load. At 210-240 W local and central rate of perceived exertion (RPE) was significantly higher with than without betablockade. IEMG increased in the same linear manner under the two conditions. No statistically significant differences in JEMG values between control and drug condition were present at any exercise intensity. Verf.-Referat