Succeeding to the previous report under the same title, in which some characteristic features in the upper limbs of the lawn-tennis players were discussed, the present report. deals with an attempt to estimate the energy expenditure in. playing lawn-tennis.
Experiments. The experiments were made with three subjects, who are all young well trained lawn-tennis players. The Douglas-Haldane method was used, the expired, air of the subject being succeedingly collected before, during and after each bout of exercises: a series of strokes or services, and a practical game of 20 minutes.
Resulte. The oxygen requirements each for a stroke, service and a practical game of 20 minutes were estimated, and the difference of the oxygen requirement owing to the difference of the form of strokes was discussed.
(1) Stroke. The oxygen requirement for a single stroke was estimated to be 82c.c. in average. In comparing a "forehand" stroke with a "backhand" one, it was noticed that the former requires more oxygen than the latter. A "flat shot" also generally requires more oxygen than a "sliceshot", and it is thought that this is essentially due to the fact that more muscular movements are necessary for the former.
(2) Service. As there are several kinds of methods in making a "service", it is obvious that the energy expenditure of a service would be very indefinite according to the difference of the methods used. But in the present case, for instance, it was revealed that the oxygen requirement for a single 1st service was 144c.c. in average and that, if it was followed up by a 2nd service, the oxygen requirement for a couple of 1st and 2nd service to be 206c.c. in average.
(3) Game One of the subjects played for a practical game which lasted for 20 minutes, carrying a Douglas-bag on his back, and his expired air was collected each for 3 minutes at certain bouts in his actual playing. As the result, the total oxygen used for this game was estimated to be approximately 31 L., thus the oxygen requirement per minute being approximately 1, 5 L. for this. game.

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