Article Review: The Physiological Meaning of the Maximal Oxygen Intake Test

Introduction

The article is related to an experiment intended to find out the physiological meaning of the maximal oxygen intake test. The maximum volume of oxygen is the maximum transport of oxygen that a human body can transport in a minute. There is a linear relation found between workload and oxygen intake. Once maximal oxygen intake per unit of time is reached, the workload can be increased but the oxygen intake level would fall. The maximal oxygen intake which a normal individual can achieve is sometimes taken as an index to maximal cardiovascular function provided pulmonary function is normal. There have been various researches conducted overtime regarding maximal oxygen intake and workload. The difficulty, insofar as maximal oxygen intake is concerned, is simply that its physiological meaning is imperfectly understood. The view that cardiac capacity is the determinant of maximal oxygen intake is an assumption, not established fact. The researchers feel that the interplay between cardiac output and AV oxygen difference during heavy work needs further scrutiny. The purpose of this paper is to examine some of the relevant relationships by direct measurement in order to ascertain the physiological meaning of the maximal oxygen intake test can be clarified.

Method

In order to establish normal data for this test, a maximal oxygen intake test was conducted with the 65 normal men. A motor-driven treadmill was used for the exercise. Each individual took a 10 minute warmup period (3 mph at 10 per cent grade), followed by a 10 minute rest period. Before the treadmill was started, the subject was connected to a Rudolph two-way breathing valve by means of a rubber mouthpiece, his nose being completely closed with a nasal clamp. For the first minute of the run, expired air was used to wash out a Douglas bag connected to the expiratory side of the valve. Expired air for analysis was collected for the last minute of a two and one-half minute run, and analysis was carried out using a Beckman E-2 magnetic oxygen analyzer and a Liston-Becker infrared carbon dioxide analyzer. Duplicate analyses were carried out regularly with a Scholander apparatus. The volume of expired air was measured in a Tissot gasometer and was corrected to STPD. These data permitted calculation of oxygen consumption either by using change in nitrogen content for correction of expired (to inspired) volume, or by use of a ...