Considerations on the physiological interpretation of the exercise test with increasing load
Casula, D.; Nissardi, G.P.; Sanna-Randaccio, F.; Carta, P.; Anni, M.S.
Bollettino della Societa Italiana di Biologia Sperimentale 51(21): 1480-1485
1975
ISSN/ISBN: 0037-8771 PMID: 1231832 Document Number: 89694
The standardized graded exercise test of the European Economic Community (EEC) is interpreted by most physiologists as a maximal test, to be interpreted on the basis of maximal O2 consumption. Such tests create problems because they require full patient cooperation. Recent work has demonstrated that test conditions can be made submaximal, thereby adapting the test to individual factors. At a certain level of muscular effort, insufficient O2 is available for aerobic glycolysis, and anaerobic glycolysis becomes an increasing factor, characterized by increased dependence on the lactic acid cycle. Lactic acid is buffered by bicarbonate, with final liberation of CO2. This is accompanied by numerous other biochemical changes. The point where this change takes place is that of maximum tolerated work (MTW), or the anaerobic threshold. Simple observations like ventilation and the respiratory quotient may be used to determine the individual MTW, thus permitting an evaluation of the EEC's graded exercise test on a submaximal basis, suitable for application to reference work standards for large scale use.