For an increasingly early mobilisation after uncomplicated myocardial infarction, the stress tests appraised the individual physicalal aptitude in supine and upright positions without incident, in a simple and objective way. To complete this evaluation, the calculation of an energetic index EI was proposed as soon as the initial level of 25 watts during cycloergometric symptom-limited stress tests in 17 male patients (increment of 25 watts for each 6 minutes and interval of one hour between the two positions). The pulmonary wedge pressure (Swan Ganz) at 15 mmHg in upright position as soon as 25 watts separated the subjects into two groups GI (N = 5) and G II (N = 12). EI 25 W had a value of 33 +/- 4 for GI and of 48 +/- 7 for GII (p less than 0.001). In the following level, EI 50W had a value of 83 +/- 14 for GI and of 109 +/- 23 for GII (p less than 0.01). Although the heart rate HR reached at the last level (expressed in % of the maximal theoretical rate) and the systolic arterial tension SAT were no different between the two groups, the subjects of GI reached a mean load of 68 watts and these of GII of 109 watts (p less than 0.01). The index EI, calculated in a simple and immediate way with HR, SAT, W and morphometric data (height, area surface) would help to evaluate the physic aptitude. Because of its harmlessness, this stress test at low load in the two positions might be repeated to define an developmental profile for each person. The prognostic value of such an index remain to be specified.