Muscular exercise, lactic acid, and the supply and utilisation of oxygen.—Parts IV-VI

Abstract

The method of studying the respiratory exchanges of man employed throughout our investigation has been that of the Douglas bag. No other method allows the same facility and accuracy in following a rapidly altering oxygen intake and carbon dioxide output. We have found it possible, during and after muscular exercise, to work with periods of collection of half a minute, and even, on occasions when it was necessary, of quarter of a minute. This makes it possible to analyse accurately the rapid alterations of oxygen intake and carbon dioxide output which occur at the beginning and at the end of muscular exercise. The gas analyses have been carried out by the ordinary Haldane’s gas analysis apparatus (large laboratory type) except in certain later experiments, where a modification (in which the gas is bubbled through the pyrogallol) introduced by D. T. Harris was used. The bags employed have been of various types, varying in capacity from 30 to 2,000 litres. They have all—some 25 of them—been made for us specially by Messrs. C. Macintosh & Co., of Cambridge Street, Manchester, and have proved an essential part of our equipment. We are glad to take this opportunity of expressing to the Company, and especially to Mr. J. S. Corker, a director, our most sincere thanks for the courtesy, completeness and expedition with which all our needs have been supplied. Some of these bags especially the smallest, but including two of 500 litres capacity, have been of the ordinary flat type as used by Douglas. Others of 150 to 300 litres capacity, employed for collecting the expired air during running or walking, have been of a truncated wedge shape, carried like a Rücksack on the back, with a sidepipe low down on the left-hand side, to enable the tap to be carried freely the left hand. (See fig. 1.) A third type (400 and 500 litres), roughly cubical in shape, was employed for prolonged collection of expired gases during recovery from muscular exercise. A fourth type (1,000 and 2,000 litres) was used, in experiments to be described later, to contain the inspired gas mixture, which on expiration was collected in bags of the other types. These may be used also to follow very prolonged recovery.