[About the effect of alcohol and tiredness on the activity of tendon reflexes (author's transl)].

In order to estimate the combined effect of ethanol and fatigue on the activity of tendon reflexes, the mechanical threshhold and the latency of the patellar tendon, the radial and the biceps reflexes as well as the time of contraction of the musculus quadriceps femoris was investigated in men, with an ethanol level in blood at 80 mg % during elimination-period, and with tired subjects meaning that they hade done their usual daywork and had been awake for about 20 to 22 hours. The group, consisting of 21 male students, was then investigated under both these conditions. The patellar reflex was elicited by a specially constructed reflexhammer, by which the mechanical power could by measured exactly, from the angle of the position the hammer was released from and its known weight. The latency and the muscular contraction time were registered with electrodes on the skin by an oscillograph. The mechanical threshhold of the patellar, biceps and radial reflexes and the latency of there reflexes were significantly and equally impaired by ethanol as well as by fatigue. The combination of both these factors resulted in an almost exactly additional effect. The contractiontime of the m. quadriceps was prolonged more by fatigue than by ethanol. Comparing these results with fromer findings, a depressing effect of the formatio reticularis of the brainstem on the activity of the spinal motorcells is to be discussed. This impairment of neuro-muscular coordination and activity obviously is dangerous for drivers. It should especially be noted, that the effect of a wake period of 20 to 22 hours can be compared with that of a bloodlevel of 80 mg % ethanol as to the impairment of the tendon reflexes.