Gesundheitstraining als eine form der primordialen prävention in einer zukünftigen arbeitswelt

During physical activity the sympathoadrenergic system plays a critical role in the regulation of muscular metabolism and haemodynamics. The heart rate, blood pressure, lactate levels and levels of free catecholamines in plasma are indicators of autonomic dysregulation resulting from inappropriate work loads in training. We investigated the effects of endurance training on these parameters with the same oxygen uptake, but at different intensities, in a group of untrained, middle-aged employees. The investigation included 31 physically healthy, untrained males in the age range from 39 to 55 years (Table I). Before and at the end of the observation period the subjects exercised on a bicycle ergometer to the limit of their individual work capacity, starting at 25 watts. The work load was increased in 25-watt steps, with each step lasting 3 minutes. The basic haemodynamic parameters and levels of blood lactate and of adrenalin and noradrenalin in plasma were assessed at rest and at work loads of 50, 100 and 150 watts. The subjects were assigned at random to 2 exercise groups. Fifteen of the men exercised at heart rates in the range of their individually determined aerobic thresholds (IAT group), and 16 subjects at their individually determined anaerobic thresholds (IANT group). All subjects performed controlled exercise on a bicycle ergometer over a period of 8 weeks, with 3 exercise units per week and an individually adjusted increment of 50 litres oxygen per exercise unit. During each exercise unit, the heart rate was monitored continuously, and in every third unit, lactate levels were assessed after 10 and 20 minutes and at the end of the session. The subject were not aware of the groups to which they were assigned (simple blind design). Statistical analysis of changes was carried out using the Wilcoxon test for dependent variables. At the end of the training period, the maximum ergometric work capacity had increased significantly in both groups and the mean heart rate and lactate levels had decreased to those seen at submaximal workloads. Interestingly, the blood pressure levels had risen to the submaximal range by the end of training in 7 subjects, all of whom were in the IANT group. All of the subjects in the IAT group experienced a distinct drop in blood pressure. These results show that in middle-aged, untrained men low-level endurance training is capable of decreasing cardiovascular risk factors. However, exercise work loads that overburden the individual's work capacity may lead to undesired adaptive responses.