New techniques for studying human muscle function, metabolism, and fatigue.

To analyze human muscle function, metabolism, and fatigue in both health and disease a variety of techniques may be employed. The most fundamental approach is the measurement of force, which may be generated by either voluntary or electrically stimulated contractions. More detailed information concerning the mechanisms of both weakness and fatigue can be obtained when the electromyogram is recorded simultaneously with force. The needle biopsy technique is recommended for the histological and histochemical examination of skeletal muscle. It has the advantage of being rapid and repeatable and has proved suitable for both diagnostic and follow-up purposes. Recently developed techniques allow the study of mitochondrial function and protein synthesis. Topical nuclear magnetic resonance spectroscopy is a new and exciting technique for the noninvasive study of muscle metabolism. The opportunities offered by this technique are largely complementary to others available and unlikely to replace them as diagnostic and monitoring tools.