Archibald V. Hill
The Nobel Prize in Physiology or Medicine 1922
Nobel Lecture, December 12, 1923
The Mechanism of Muscular Contraction
In investigating the mechanism involved in the activity of striated muscle two points must be borne in mind, firstly, that the
mechanism, whatever it be, exists separately inside each individual fibre, and secondly, that this fibre is in principle an
isothermal machine, i.e. working practically at a constant temperature. There are several ways of studying this machine - the
mechanical, the thermodynamic, the chemical, and the electrical, and of course any combination of these. In the case of
nerve, much information has been acquired from a study of its electrical properties especially recently in the hands of Keith
Lucas, Adrian, and Erlanger and Gasser. In the muscle fibre, however, as distinguished from muscular tissue in general,
comparatively little has been discovered by studying the electric change. The apparent exception of the heart is not a real
one, since here the electric change has been used to analyse, not so much the behaviour of the individual fibre - that is, of the
ultimate mechanism itself - as the distribution and interconnection of the fibres to form the complete working organ. We will
not therefore consider the electrical phenomena further in our discussion of the mechanism of the muscle fibre.
Much investigation has been devoted in the past to the mechanical response and characteristics of muscles, and it might have
appeared that this subject is to some degree worked out and unlikely to yield further results of value. Actually, however, in
combination with thermodynamical observations and considerations, much information has been derived recently from a study
of the mechanical output and behaviour of muscles. Indeed, in the last two or three years the investigation of the connection
between the rate of shortening, the work done and the heat production has pointed to new, hitherto unsuspected,
mechanisms in muscle which are of considerable theoretical interest and practical importance.
The chief advances, however, during recent years have come from a study of the thermal and the chemical changes which
occur in excised muscle. These two sides of the investigation are the ones which Professor Meyerhof and I will discuss today.
One of the fundamental characteristics of striated muscle, and the one involving the greatest difficulty in investigation, is the