” Some muscles can lift a thousand times their own weight; some can exert a tension of forty pounds per square inch of their cross section. The muscle of a clam can keep a viselike grip for hours without apparently consuming any energy. The muscles of our hearts and our lungs work from the cradle to the grave without stopping. In Methuselah’s case that was for 969 years! (Gen. 5:27)

In smooth muscles the filaments that do the actual work of contracting are arrayed in parallel, overlapping one another, and at an angle of as much as 10 percent to the long axis of the muscle cell. This oblique arrangement of the filaments in smooth muscles may give them as much as ten times the strength that they would otherwise have and so enables them to sustain forceful contractions over long periods of time. On the other hand, the way the filaments lie in voluntary or striped muscles, in series or end to end, permits them to move with greater velocity or speed. And the amount of contraction can be far greater than in smooth muscle. This is just what these voluntary muscles need to do to serve man well. They surely give evidence of a wise Designer.

The muscle of the heart is in a class by itself. Because of its great work load it has a special kind of construction, making it the strongest muscle in man. In woman, only the muscle of the uterus, needed to expel a baby at birth, is said to be stronger.