Table tennis, like tennis, squash and badminton, is a racket sport. All these sports have in common a rapid succession of mostly short-term maximal or submaximal efforts and short recovery phases. The goal of this paper is to investigate the psychophysical stress in table tennis by means of the stress hormones epinephrine and norepinephrine. The catecholamines were determined from urine samples. 16 Austrian top-level table tennis players were examined. There were 8 female and 8 male players in this group. The catecholamine excretion at rest (R), training (TR), practice competition (PC), competition (C) and treadmill ergometry (TE) are indicated in ng/min of collecting time. When the group is divided according to sex, we find marked differences in the catecholamine release. While the epinephrine excretion during and after training and practice competition is basically the same, it is lower during and after treadmill ergometry and higher after competition. The same result was found with respect to norepinephrine excretion. The ratio between norepinephrine and epinephrine was 4:1 at rest and during and after treadmill ergometry, 6:1 during and after training, 5:1 during and after the practice competition and 2:1 during and after the competition. The investigation showed that a table tennis competition puts high stress on the player. The mental component should therefore receive much more importance in order to keep the stress low.

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S U M M A R YI. The effects of hypercapnic acidosis on coronary conductance, the coronary dilator effect of adenosine administered into the coronary artery and the reactive hyperaemic response after short and long periods of coronary artery occlusion were investigated in thoracotomized dogs.2. The coronary conductance was positively correIated to the arterial Pco2 and negatively correlated to the arterial pH.3. During control periods the reactive hyperaemic response increased with increasing duration ofcoronary artery occlusion, whereas the percentage repayment of the deficit remained unchanged.4. The reactive hyperaemic response after short periods of coronary artery occlusion (up to ten beats) was diminished during hypercapnic acidosis. This decrease may be explained on the basis of an increased tissue Poz or a decreased relative change in tissue pH.5. The dilator effect of adenosine administered into the coronary artery was enhanced during hypercapnic acidosis.6. The reactive hyperaemic response after long periods of coronary artery occlusion (above fifteen to twenty beats) was also enhanced during hypercapnjc acidosis, and may be a result of myocardial adenosine formation during coronary artery occlusion.7. The findings indicate that coronary blood flow after coronary artery occlusions may be primarily regulated by local pH changes in the coronary vessel cells. Additional dilatation after longer coronary artery occlusion may result from the release of adenosine by the hypoxic myocardium.