(from the article `muscle`) When a muscle is to lift a constant load (isotonic conditions) after stimulation starts, the force increases, just as in an isometric contraction, ...
Muscular contractions characterised by increase in tension without change in length. ... (12 Dec 1998) ... 
muscle contraction without appreciable shortening or change in distance between its origin and insertion. Isotonic (A) and isometric (B) contraction.
Type: Term Definitions: 1. force development at constant length.
(i;suo-met;rik) Muscle contraction in which there is no appreciable shortening of the muscle.