RESEARCHES BY OTHER INVESTIGATORS. 7 



observed values by a formula differing from that of Brezina and 

 Reichel. They conclude that neither their own formula nor that of 

 Brezina and Reichel expresses a physiological law and that they are 

 useful solely as interpolation formulae. They also find that by applying 

 their equation to some 150 experiments made at speeds of 55, 82, and 

 110 meters per minute, the optimum rate of walking was approximately 

 82 meters per minute, a value close to that found by Durig. 



GENERAL CONSIDERATIONS WITH REGARD TO PREVIOUS RESEARCHES ON 



HORIZONTAL WALKING. 



From the large mass of evidence obtained in European and American 

 laboratories on the metabolism during horizontal walking, it can be 

 seen that no little portion of it has been accumulated with the primary 

 object of the transportation of loads. This has in part been neces- 

 sitated by the technique employed in the Zuntz school of carrying 

 on the back a rather cumbersome and weighty meter with its attach- 

 ments, and in part by the fact that interest has been stimulated by 

 Alpine touring. Certain fundamental experiments have been made in 

 laboratories by means of treadmills. When a pack was not trans- 

 ported the results of these earlier experiments are perfectly comparable 

 with those with free walking. They are, however, even at best, too 

 few, and accumulation of further evidence is entirely justified. 



Practically all of the results point towards the excellence of the 

 work carried out under the supervision of Durig. Inherently, per- 

 haps, no further investigation on horizontal walking per se is justifiable 

 with the great number of other problems on walking which await 

 solution. Durig's main problem was the study of the metabolism 

 for the work of ascent, but unfortunately nearly all of his work included 

 not only the transportation of a load but the use of a cumbersome, 

 unweildy gas-meter carried on the back. That these conditions do 

 not call into play a much larger degree of muscular coordination than 

 would ordinarily be required in free walking is difficult to believe. 

 On the other hand, it is clear that Durig's values for the energy required 

 to transport 1 kg. a horizontal meter are closely in accord with the 

 results of practically all the work done by other methods, although, as 

 a rule, they run slightly higher, which would be expected from the 

 nature of the technique. 



Two important points must be considered : First, that for all investi- 

 gations on grade walking, clearly established base-lines are necessary. 

 These can best be obtained by actual test, i. e., by having the subject 

 walk on a horizontal plane under exactly the same conditions as he sub- 

 sequently walks on a grade. This particular factor influences in large 

 part the accumulation of the material on horizontal walking to be 

 given in the present report. 



Secondly, evidence has been forthcoming, although unfortunately 



