216. Increased Use Of Oxygen From Work

No one can have failed to notice that physical exertion, especially if it is quite severe, is attended with more rapid breathing, a quicker pulse, and in warm weather a flushed face and abundant perspiration. An interesting table which has been compiled from data given by Benedict and Carpenter1 shows the relation of pulse-beat to heat production and carbon-dioxid elimination: -

TABLE XXXIII

Increased Carbon Dioxid

Increased Heat Production

Increased Pulse Beat

Per Cent

Per Cent

Per Cent

38.9

52.0

35.7

8.9

10.2

16.1

29.0

31.2

19.6

49.2

53.0

22.9

37.9

34.5

12.9

13.0

13.1

21.1

30.0

38.0

25.0

There is an entirely rational explanation for these phe-nomena. Increased work requires an increased expenditure of enerey, that is, an increased use of oxygen for developing the potential energy of the absorbed food. As heat is the final or waste product of muscular energy, an increase of mechanical work performed by the muscles causes an increase of heat, which must be radiated from the body. The relation of muscular exercise to the use of oxygen and heat production is made clear by the following tablel (Sitting = 100): 1 " Metabolism and Energy Transformations of Healthy Man during Rest," p. 250.

Table XXXIV. Effect Of Muscular Exercise On Energy Use

TABLE XXXIV

Effect of Muscular Exercise on Energy Use

Carbon Dioxid Eliminated

Oxygen Absorbed

Heat Produced

PerCent

Per Cent

PerCent

Man at rest, sleeping ....

70

79

73

Man at rest, awake, sitting . .

100

100

100

Man at rest, standing ....

112

116

117

Man at severe muscular exercise.

746

786

673

Above eight times more oxygen is used, and seven times more heat evolved during heavy work than during rest.