The energy used in "sprint" running

Abstract

The mechanical work done in sprint running against the viscous resistance of the muscles of a runner has been compared with the amount of O2 used in recovering from the effort. The result shows a mechanical efficiency of about 38%. The meaning of this high value is discussed. In a man running 200 yards at. top speed, fatigue begins to appear after 70 yards and by the end the speed has fallen on the average by 12%. There are individual variations, trained long distance runners showing less diminution of speed. This fatigue is due to the enormous rate of expenditure of energy in rapid running. One subject who ran his first 100 yards in 9.88 secs, and his 2nd in 9.57 secs, was developing 81/2 horsepower at his maximum velocity (11.46 yards per sec.) and liberating more than 4 gm. of lactic acid per sec. in his muscles.