In this first published research on human muscle atrophy consequent upon immobilization in plaster casts Professor Anthony J Sargeant demonstrated that gross anthropometric measurement of leg muscle size vastly underestimated the magnitude of the reduction in cross sectional area of the muscle fibres themselves. Needle biopsies of the quadriceps muscle in young military personnel who had simple leg fractures and had been immobilized in plaster casts for between 6-12 weeks showed that the muscle fibres were reduced by nearly 50% in cross sectional area. This reduction would lead to a concomitant reduction in the maximum force that the muscle could generate.Furthermore the study indicated that even with intensive residential rehabilitation the rebuilding of muscle fibre size was a very slow process. Indeed subsequent studies and observations suggest that full recovery of muscle fibre size may never be recovered in the injured legs in many people suffering leg injury and consequent immobilization. It appears that the time course of muscle loss and muscle gain is asymmetric with loss of muscle occurring rapidly, within days of immobilization, while recovery of muscle size takes many weeks.
Clinical Science and Molecular Medicine
Clin Sci Mol Med. 1977 Apr;52(4):337-42