Muscle function: a personal view.

We are far more likely to arrive at our destination if we know what it is. For those of us who are interested in how muscles work, the destination is the progressive unification of our knowledge of the physics, chemistry and structure at all levels of muscular systems. The same integration is needed to understand other organs, but in my opinion the field of muscle research has progressed further than the others. Optimists that we are, our goal seems almost within our grasp. Perhaps it is just at the rainbow's end . . . The need to relate muscular structure to its mechanical function has been apparent for centuries. Certainly it was clear to Galileo and Borelli (both of whom understood dimensional analysis), and to Leonardo da Vinci (who understood most things). To my mind, William Harvey is pre-eminent in this regard, because he added the stem discipline of experimentation with all its cussedness to control the somewhat easier task of speculation. By the late 18th century the relationship between living function and the then new subject of chemistry was emerging from the work of geniuses like Priestley and especially Lavoisier. As early as 1807 the great Berzelius 'convinced himself that the amount of free lactic acid in a muscle is proportional to the extent to which it has been previously exercised.' (Quotation from Lehmann, 1851). This conclusion (with a few refinements) remains valid today. The great achievements of the 19th century seem to me to be (not in order of importance): (1) The perfection of our knowledge of gross anatomy. (2) A great increase in our knowledge of chemistry and physics. This led to the dismissal of 'vital forces', i.e. the notion that living processes were in some essential way different from non-living ones. Liebig and Pasteur were among the giants who settled this issue. (3) The demonstration of the continuity of life, i.e. the absence of 'spontaneous generation'. In this Pasteur also played a key part. (4) Methods of light microscopy were brought almost to their modern state of perfection. However, we should never forget what amazing things Leeuwenhoek saw 200 years before, using a simple lens and a sharp mind. The observations made on living muscle during the 19th century were in fact more accurate than the ones that dominated the scene in my youth. This salutary warning story is brilliantly told in the (1957) review by Andrew Huxley.