To specify work performed when a force is acting on a body we must know three pieces of information: 1  Average force acting on a body. 2  Direction of that force.  Displacement of the body in the direction of the acting force during the time when the force is acting on the body.
http://www.fsps.muni.cz/~tvodicka/data/reader/book-2/28.html
Muscle contractions can be described based on two variables: length and tension. A muscle contraction is described as isometric if the muscle tension changes but the muscle length remains the same. In contrast, a muscle contraction is isotonic if muscle length changes but the muscle tension remains the same. If the muscle length shortens, the contraction is concentric; if the muscle length lengthens, the contraction is eccentric.
https://en.wikipedia.org/wiki/Muscle_contraction
In a PVC, the ventricles contract first and before the atria have optimally filled the ventricles with blood, which means that circulation is inefficient. However, single beat PVC abnormal heart rhythms do not usually pose a danger and can be asymptomatic in healthy individuals. A PVC is a type of ectopic beat.
https://en.wikipedia.org/wiki/Premature_ventricular_contraction
A premature ventricular contraction ( PVC ) — also known as a premature ventricular complex , ventricular premature contraction ( or complex or complexes ) ( VPC ) , ventricular premature beat ( VPB ) , or ventricular extrasystole ( VES ) — is a relatively common event where the heartbeat is initiated by Purkinje fibers in the ventricles rather than ...
https://en.wikipedia.org/wiki/Premature_ventricular_contraction
Work of force F acting on a body can be defined in several ways. where W45 is work (J), F is the magnitude of force (N), and d is displacement of the body (m). Work is product of force and displacement of a body along the same line as that force is acting. 1  Average force acting on a body.  Direction of that force.
http://www.fsps.muni.cz/~tvodicka/data/reader/book-2/28.html
Though the muscle is doing a negative amount of mechanical work, (work is being done on the muscle), chemical energy (in fat, glucose or ATP) is nevertheless consumed, although less than would be consumed during a concentric contraction of the same force.
https://en.wikipedia.org/wiki/Muscle_contraction
Force itself can be differentiated as either tension or load. Muscle tension is the force exerted by the muscle on an object whereas a load is the force exerted by an object on the muscle. When muscle tension changes without any corresponding changes in muscle length, the muscle contraction is described as isometric.
https://en.wikipedia.org/wiki/Muscle_contraction
In a normal heartbeat, the ventricles contract after the atria have helped to fill them by contracting; in this way the ventricles can pump a maximized amount of blood both to the lungs and to the rest of the body.
https://en.wikipedia.org/wiki/Premature_ventricular_contraction
During a concentric contraction, a muscle is stimulated to contract according to the sliding filament theory. This occurs throughout the length of the muscle, generating a force at the origin and insertion, causing the muscle to shorten and changing the angle of the joint.
https://en.wikipedia.org/wiki/Muscle_contraction
Work, Energy, and Power. Work. Work of force F acting on a body can be defined in several ways. where W45 is work (J), F is the magnitude of force (N), and d is displacement of the body (m). Work is product of force and displacement of a body along the same line as that force is acting. Average force acting on a body.
http://www.fsps.muni.cz/~tvodicka/data/reader/book-2/28.html
what kind of energy is contraction force on ventricles
The contraction force on ventricles is PVC kind of energy.