Isotonic contraction

In an isotonic contraction, tension remains the same, whilst the muscle's length changes. By contrast, in isokinetic contractions, the muscle speed remains constant, whilst the tension changes. As the muscle's force changes via the length-tension relationship during a contraction, an isotonic contraction keeps force constant while velocity changes, whereas an isokinetic contraction keeps velocity constant while force changes. A near isotonic contraction is known as Auxotonic contraction. There are two types of isotonic contractions: (1) concentric and (2) eccentric. In a concentric contraction, the muscle tension rises to meet the resistance, then remains the same as the muscle shortens. In eccentric, the muscle lengthens due to the resistance being greater than the force the muscle is producing.