Cr. Worthington et Gf. Elliott, MUSCLE-CONTRACTION - THE STEP-SIZE DISTANCE AND THE IMPULSE-TIME PER ATP, International journal of biological macromolecules, 18(1-2), 1996, pp. 123-131
We derive the step-size distance, and the impulse time per ATP split,
from a consideration of Hill's energy rate equation coupled with the e
nthalpy available per ATP split. This definition of step-size distance
is model-independent, and is calculated to have a maximum of 17 Angst
rom at no load and to reduce to zero at isometric tension, since it wi
ll depend on the velocity of shortening. We revisit a derivation of Hi
ll's force-velocity equation depending on impulsive forces working aga
inst frictional forces and show that this gives a physical meaning to
Hill's constants a and b. This is particularly elegant for Hill's cons
tant b, which is directly related to the impulse time; the value of th
is impulse time is 1/2 ms. The question that muscle contraction may in
volve overlapping interactions is considered. However, we find that th
e step-size distance is not dependent on the possibility of overlappin
g interactions.