Myocardial oxygen consumption in isometric contraction of various strengths due to paired stimulation and quick-release

In all of the experiments described, the oxygen consumption during isometric contraction was dependent solely upon the magnitude of active tension developed, and not on the rate of tension development or on the duration of contraction. There is a constant linear relationship between tension development and oxygen uptake. Any sudden interruption of active tension in the rising phase of the contraction terminates the energy utilization by the contractile system. These findings provide evidence to suggest that in isometric contraction of heart muscle, a rigid and constant coupling exists in the transformation of chemical energy to the mechanical tension.