A study of the sugar and oxygen relationships in the blood of dogs during exercise

Abstract

As a phase of our investigation of the chemical changes in the organism resulting from exercise, the following study of the sugar and oxygen relationships in the blood of dogs was undertaken.

Samples of blood amounting to about 1 per cent. of the body weight were drawn from the external jugular vein. Determinations of the blood sugar by the MacLean method, of the oxygen by the Van Slyke technique, and of the volume of the corpuscles by a precision hematocrit were made every two hours during the course of six-hour working periods. During these periods the dogs ran on an electrically-driven, horizontal treadmill at the rate of about five miles per hour. For each such experiment, we made a corresponding series of control observations on the same dog similar in all respects save that the exercise factor was eliminated. The figures given in the table are the averages of the data obtained from five dogs.

The fact that the averages of the initial samples are so nearly identical for each constituent, indicates that our series is sufficiently long to permit the attaching of significance to subsequent variations.

Since it is desirable to compare figures which were obtained under conditions identical except for the added element of exercise, we wish to point out that in studying the table the figures given for exercise should be compared with the figures for the corresponding periods of rest, rather than with the initial values for the exercise experiments. This is indeed necessary in the interpretation of the effect of work because variations of significant magnitude in the control series make comparisons between initial and successive periods unjustifiable for this purpose.

From the table it will be seen that the oxygen content of the blood rises during the first period of work as compared with the first period of rest and falls slightly thereafter.