isometric relaxation

i·so·met·ric re·lax·a·tion

decrease in tension of a muscle while the length remains constant because of fixation of the ends.

i·so·met·ric re·lax·a·tion

(īsō-metrik rĕ-lak-sāshŭn) Decrease in tension of a muscle while the length remains constant because of fixation of the ends.