Plasma catecholamines, atrial natriuretic peptide and blood lactate responses during upright bicycle ergometry with incremental steps adapted to individual maximal work capacity.

To assess whether hormone and metabolic responses in an upright bicycle exercise test are equivalent for subjects with different physical characteristics if test duration for reaching individual maximal work capacity (PWCmax) is standardized we investigated plasma catecholamines, human atrial natriuretic peptide (hANP) and blood lactate responses in twenty healthy sedentary subjects. Ten male (38.5 +/- 4.7 yrs) and ten female (34.5 +/- 6.4 yrs) healthy volunteers performed two ergometries, a first one with incremental steps of 25 Watts each for two minutes to determine PWCmax, and a second one with incremental steps of PWCmax/6. According to this definition a test duration of 12 min was attained for all subjects for the second ergometry. The results show that the increase of the rate pressure product (RPP) as an index of relative cardiac work is significantly different between the male and female group in the test with constant 25 Watts steps. But with the modified exercise test RPP/time-slopes are nearly identical, identicating equivalent cardiac work due to gender and body surface. Similar results are obtained for plasma catecholamines, hANP and blood lactate. Mean values did not differ in the modified exercise test between the male and female group either in the sub-maximal range or at PWCmax. In conclusion, our data suggest that in a maximal exercise test with equal test duration, and considering individual physical properties for the calculation of incremental steps hormonal and metabolic responses are equivalent. It seems that the designed, modified exercise test provides inter-individual comparisons at least for these investigated parameters. The test may be helpful if catecholamines, hANP or lactate are used as diagnostic parameters in patients.