What is Isotonics?

Kelly Ferguson

The term isotonics refers to the concentric contraction of muscles around a joint in a distinct manner. Specifically, in isotonic muscle contractions, the muscle contracts with the same amount of force throughout the entire motion, though the speed of the contraction may change. This point is important because it distinguishes it from a different kind of motion called an isokinetic motion, which occurs when the speed of the contraction remains the same but the force that the muscle exerts throughout the motion may vary. Sometimes people use the word isotonics to refer to certain weight lifting exercises. Indeed, weight lifting exercises such as bicep curls and similar motions are common examples of isotonic contractions.

A bicep curl is a common type of isotonic contraction.
A bicep curl is a common type of isotonic contraction.

Isotonics are generally considered to be a valuable part of any fitness plan, whether one is training for sports, weight loss, or just overall health. Isotonic exercises and workout plans can be personalized to fit almost any individual’s personal goals and physical limitations. They are often an extremely important part of physical therapy, helping to rehabilitate the body following surgery or trauma. Resistance training, when done correctly, improves the strength of not only the muscle tissue but also the bones, joints, and connective tissues. Muscle training can dramatically improve health and well-being, and reduce the effects of aging on the body.

Isokinetics are typically better than isotonics at building muscle mass.
Isokinetics are typically better than isotonics at building muscle mass.

The downside to using isotonics to build muscle strength and mass is that, with isotonic contractions, the leverage of the muscles around the joint vary at all of the different points throughout the muscle contraction. This means, essentially, that some areas of the muscle are worked more heavily than other areas, leading to one specific area where the most force has been exerted and therefore the most strength gained. Many people believe that the ideal way to build strength and muscle mass is not with isotonics, but with isokinetics, which train the muscle evenly along the entire length. Currently, though isotonic exercises trail behind isokinetic exercises as the most efficient exercises to build strength and muscle mass, they are much more convenient, requiring only weights or other resistance instead of the expensive equipment needed to produce a true isokinetic contraction. When combined with other exercises, including cardiovascular exercises in addition to other strength training options like isometric exercises, there is little reason why isotonic training is insufficient to help an individual improve his or her health and fitness.

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