Apparatus has been developed for the measurement of shortening and tension of isolated muscle using variable capacitance methods. An isotonic transducer is described which will measure up to 2.5 cm of shortening with a minimum of inertial loading with 1% linearity. An isometric transducer is described which will measure tensions up to 100 g with not more than 5‐&mgr; displacement from 0 to 200 cycles/sec. Simple modifications provide other ranges of tension.