Abstract: The invention relates to a method for measuring the working condition of muscles, and to a measuring and training system for measuring the working condition of muscles and muscle training. Muscles are loaded with mechanical devices, the working condition of muscles is measured with measuring equipment, and the obtained results are registered. According to the invention, from among a number of separate, independent muscle training devices, there is chosen one, whereby the muscles are loaded, and the working condition of muscles is measured by means of the sensors provided therein. The sensors of the training device are connected, by means of a connector element, to a data processing unit, and the chosen type of training device is identified to the data processing unit, whereafter the measuring program, corresponding to the training device in question, is activated.