Bodies, Sport and Science in the Nineteenth Century

Peer-reviewed history of physiology article documenting the experimental programme that refuted Liebig's protein-fuel hypothesis for muscular work. Details Fick and Wislicenus's 1865 Faulhorn mountain-ascent self-experiment, in which they restricted protein intake, climbed the mountain, and measured nitrogen excretion; the nitrogen excreted was insufficient to account for the mechanical work performed, demonstrating that non-nitrogenous nutrients (fats and carbohydrates) must supply a substantial portion of muscular energy. Also documents Voit's 1860 dog treadmill experiments and the Voit-Pettenkofer human respiratory chamber studies from 1866 onward, which strongly suggested that bodily energy drew on sources other than dietary protein. These studies collectively demolished the theoretical basis for Liebig's meat extract as a concentrated energy food.