A new molecular model is proposed for muscle contraction, that involve
s the electrical charging of the long (C-terminal) alpha-helical part
of the head of the myosin molecule (S1) while the head is attached to
actin; as it charges the alpha-helical part moves in the radial electr
ic field between the filaments. The alpha-helical part snaps back when
the myosin molecule is discharged electrically, at the moment that AT
P binds to the active enzymatic site. This snap-back model explains se
veral puzzling phenomena in contractility, as well as providing a phys
ical explanation for the origin of an impulsive force that drives musc
le contraction.