title: The energetics of work and heat production by single muscle fibres from the frog.
abstract: During active shortening the heat rate in isolated muscle fibres is greater than during isometric contraction, and increases with velocity of shortening (V), but at a decreasing rate as the maximum velocity (V0) is approached. For shortening at V less than 0.25 V0 the amount of extra heat produced during a period of shortening is proportional to the distance shortened, but for rapid shortening (V greater than 0.5 V0) the extra heat increases less than proportionally with the distance shortened. After a period of shortening the higher heat rate returns to the isometric level over a period of several hundred milliseconds. A similar period of increased heat rate is seen after a quick release. After shortening 10% of muscles slack length at 0.1 V0 the amount of heat produced during tension redevelopment is similar to that after a quick release. But after more rapid shortening there is less heat production than after a quick release.
authors.affiliation: Department of Physiology, University College London, U.K.
authors.forename: R C
authors.initials: RC
authors.lastname: Woledge
authors.forename: M G
authors.initials: MG
authors.lastname: Wilson
authors.forename: J V
authors.initials: JV
authors.lastname: Howarth
authors.forename: G
authors.initials: G
authors.lastname: Elzinga
authors.forename: K
authors.initials: K
authors.lastname: Kometani
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D066298:In Vitro Techniques; D007537:Isometric Contraction; D008962:Models, Theoretical; D009119:Muscle Contraction; D009126:Muscle Relaxation; D009132:Muscles / Q000502:physiology*; D011898:Ranidae; D013816:Thermodynamics
chemical_list: D000255:Adenosine Triphosphate