1. A new method of studying isolated human skeletal muscle has been evaluated. This involves the incubation and electrical stimulation of strips of muscle, obtained at surgical biopsy, that are tied at the cut ends of the fibre bundles.
2. Morphological examination showed that the fibres were sealed off at the cut ends. Damage appeared to be restricted to the areas immediately adjacent to the ties.
3. Contractile properties were well maintained for several hours and measurements of tissue metabolites showed that muscle contents of the high-energy phosphate compounds were well preserved.
4. The isolated preparations were found to have the same contractile properties as human quadriceps femoris studied in vivo by the methods described in the preceding paper.
5. Correlation was found between the relaxation speed of the isolated preparations and their fibre-type composition histochemically determined.
6. It is concluded that this technique is a valid addition to the present methods of studying the physiology and pharmacology of human skeletal muscle.