Abstract: The invention relates to a method and a filter for distinguishing signal components from one another, whereof at least one comprises a periodic signal sequence. In the solution samples are taken during several signal sequences (300) and a signal sequence model is formed by arranging the samples taken from several signal sequences (300) together so that the samples represent a single signal sequence (300) model and the signal sequence model is specified by filtering.

Abstract: The present invention relates to a method and an apparatus for measuring exercise condition, especially a method for measuring an exertion endurance indicator representing exercise condition of a subject to be measured, such as maximal oxygen uptake or any such exertion endurance indicator representing exercise condition. The method is characterized in that, in the method a predetermined calculation formula is used preferably by means of a neural network, to which formula physiological parameters representing the subject to be measured are supplied. The input parameters comprise at least one or more of the following physiological parameters, such as sex, age, height, weight. One or more output parameters representing the exertion endurance indicator representing the exercise condition of the subject to be measured are obtained as a result from the calculation formula.