Mabch 26, 1909] 



SCIENCE 



487 



taken. What are the physiological effects 

 of the training for and the participation 

 in such efforts? 



The contribution of the physiologist to 

 the answer to this question must be limited 

 to a statement of what is known of the 

 physiological conditions during strain. It 

 is for the clinician to tell us how far these 

 dangers actually produce ill effects; and 

 the clinical evidence, to be at all satisfac- 

 tory, must be drawn, not simply from the 

 study of cases which apply for treatment, 

 but from a systematic study of an entire 

 group of average people participating in 

 such work. For it must be remembered 

 that the appeal of athletics is not simply 

 to those who will finally make a school or 

 college team, but to a much larger propor- 

 tion of the student body. 



First, I think we should make sure that 

 we appreciate the weight of the burden of 

 physiological adjustment which muscular 

 activity places upon the organism, for this 

 is always greater than is generally sup- 

 posed. It may be measured with a fair 

 degree of accuracy by the respiratory ex- 

 change, since this varies almost pari passu 

 with the work. The comparison must, 

 however, be made between the expired air, 

 collected directly from the respiratory pas- 

 sages, during rest and during the actual 

 performance of work. Measurements 

 made in respiration chambers, unless the 

 work extends over several hours (and very 

 severe work can not be maintained con- 

 tinuously for this length of time), neces- 

 sarily involve some lag in the collection of 

 the samples. I will quote from two re- 

 liable observations involving such direct 

 analyses of the expired air. 



Leo Zuntz^ found that the oxygen con- 

 sumed per minute while riding a bicycle 

 on a level asphalt track at a speed of nine 

 miles an hour increased from 263 c.cm. 



' Leo Zuntz, " Untersuchungen liber den Gas- 

 ■wechsel und Energieumsatz des Radfahrers." 



(during rest) to 1,550 c.cm., and that when 

 the speed was increased to thirteen miles 

 an hour it rose to 2,058 c.cm., an in- 

 crease of eightfold. This corresponds very 

 closely with what Zuntz and Lehmann* 

 had previously found for the horse, where 

 the oxygen consumed and the carbon diox- 

 ide excreted per minute increased from 

 five to ten fold with moderately heavy to 

 hard work, respectively. All observations, 

 moreover, show that this respiratory need 

 must be met at once, which means an 

 enormous increase of work on the part of 

 the respiratory and vascular systems. 

 "When we find the muscular work of the 

 sitting posture almost doubling that of the 

 sleeping condition; even light activity 

 doubling the work of the sitting posture; 

 only moderately heavy work increasing it 

 four or five fold, while vigorous activity in- 

 creases it eight and ten fold ; and when we 

 refiect that all this must be immediately 

 provided for in the successful readjust- 

 ment of the circulation and respiration — 

 we begin to appreciate the possibilities of 

 physical strain. 



Two very different forms of muscular 

 activity introduce into the organism con- 

 ditions of strain and the nature of the 

 strain in the two cases is very different; 

 first, when a supreme effort is put forth 

 suddenly and for comparatively brief 

 periods of time, as in the hundred yards' 

 dash; and, second, where vigorous but less 

 violent exertion is prolonged over a much 

 greater time, as in long-distance running. 

 Probably the chief dangers in the two 

 cases are, respectively, excessive arterial 

 pressure, at times combined with dis- 

 turbance of the pumping action of the 

 heart, and fatigue. 



With regard to arterial pressure during 

 muscular activity, the reliable data at 

 hand are sufficient to give us an idea of 



' Zuntz and Lehmann, " Stoffwechsel des Pfer- 

 des," Berlin, 1889. 



