A portable lightweight Douglas bag instrument for use during various types of exercise.

A construction outline of lightweight portable equipment for VO2 measurements by the Douglas bag method is given. The equipment consists of three separate units: an inspiration-expiration valve, a switch directing the expiratory flow, and a disconnectable bag with stopcock. The ease of operation assures good reproducibility of the results. Experiences during maximal speed skating are described. Use of the equipment demands only simple operations by the subject, which do not interfere with the exercise.