By some estimates, calcium handling eats up 30-50% of the ATP used in muscle contraction, so a change in calcium sensitivity could indeed explain why nitrate makes endurance exercise more efficient.

Huxley, A. F. & Niedergerke, R. Structural changes in muscle during contraction: Interference microscopy of living muscle fibres. Nature 173 , 971–973 (1954) doi:10.1038/173971a0.

The flow of water within a muscle fiber may dictate how quickly muscle can contract, according to a University of Michigan study.

A research group has uncovered important details about how platelet-activating factor (PAF)—a powerful molecule involved in inflammation and allergic reactions—triggers contractions in the smooth ...

In vascular strips, the adjacent endothelial cells modulate the contraction of vascular smooth muscle cells (VSMCs) induced by sphingosylphosphorylcholine (SPC) through nitric oxide (NO). The aim ...