Heart rate, metabolic and hormonal responses to maximal psycho-emotional and physical stress in motor car racing drivers.

Motor car racing is representative of concentrative sporting activities, as well as instructive for mental-concentrative and psycho-emotional stress, which predominates with lower intensity, but longer duration in occupational work of today. A group of 20 car racing drivers was investigated both during car races (Formula Ford and Renault-5-Cup) and during progressive bicycle ergometry in the laboratory. Heart rate during car racing reached a mean level of 174.3 +/- 14.1 min-1 (mean +/- SD), corresponding to 90% of the maximal heart rate achieved at the end of exhaustive ergometry (n = 12). Catecholamine excretion in urine (adrenaline + noradrenaline) on average was 252.3 +/- 77.9 ng min-1 during car racing and 121.9 +/- 37.3 ng min-1 during exhaustive ergometry (n = 10). Most of the other metabolic parameters determined in blood (lactate, glucose, FFA = free fatty acids, plasma protein, insulin, HGH = human growth hormone) also showed significant differences between car racing and bicycle ergometry (n = 20). Therefore it is possible to distinguish between psychical and physical strain and the quantify their specific level. Especially blood lactate can be considered as a metabolic indicator of physical strain and FFA of psycho-emotional strain. Furthermore, significant negative correlations could be found between heart rate, FFA level, and catecholamine excretion during car racing and some measures of physical fitness determined on the bicycle ergometer (n = 12 or 10). This suggests a reduced cardiocirculatory and metabolic strain reaction in response to psychical stress situations with increased fitness. Moreover, HDL (high density lipoprotein) was found increased and oral glucose tolerance test was improved with elevated physical fitness (n = 20, respectively 16). From the results of this study it can be concluded that physical activity counteracts atherosclerosis and CHD (coronary heart disease), which are promoted by psycho-emotional and psycho-social stress.