In real world domains, such as medicine, biochemical index is by nature imprecise. As a consequence, the expert systems oriented to these domains must have specific tools to deal with the uncertainty. How to interpret the results of laboratory tests (we refer to the area of exercise intensity diagnostics). The theory of fuzzy sets provides a systematic framework for dealing with fuzzy quantifiers. Amaya and Beliakov (1995) showed how to build the membership function for the intersubject fuzziness and presented a method for interactive refinement of the obtained curves. We follow the Amaya and Beliakov's (1995) model to employ the same inference engine used to deal with the imprecise information provided by measuring the physiological and biochemical data of athletes.However, in some cases the derived curves have not been accepted by the experts. This could be due to lack of statistical data or experience. Therefore, the further process requires interactive refinement of the corresponding possibility distribution.