Research has been performed exercises that incorporate isometric contractions in conjunction with other types of muscle contractions to determine if the additional tension development in the muscle will increase the strength development more quickly. Ideally, strength development should occur throughout the entire available range of motion of a given joint.

Unfortunately, the development of tension in the muscle during an isometric contraction is isolated to one length of muscle and one range of motion of the nearby joints. Isometrically contracting the muscles in the injured body part helps to increase blood flow and neuromuscular activity at the injury site. This helps the person use the injured body part to begin the strengthening process while protecting it against further damage.

Isometric exercises are often used due to the safety of no muscle movement or joint motion. In rehabilitation settings, Physical Therapists seek to restore strength while also limiting muscle movement or joint motion in the injured area. Lastly, isokinetic contractions occur when the muscle develops tension, but the speed of movement is maintained throughout the range of motion. Studies indicate that eccentric contractions help to develop muscle strength more quickly than concentric. There are two types of isotonic contraction, concentric (the muscle shortens) and eccentric (the muscle lengthens). Isotonic exercises produce tension in the muscle and the muscle changes lengths. Isometric exercises generate tension in the muscle, but there is no change in muscle length or joint motion. The increase in strength in the muscle will coincide with the development of larger muscle cells which is known as hypertrophy. If the tension is great enough, the muscle tissue will respond physiologically at the cell level and an increase in strength will occur in the future providing the increased tension is repeatedly developed by that muscle mass. The three types of contractions are capable of creating tension within the muscle. A muscle is more like a rubber band than a leather belt. Muscles are capable of contracting because they consist of a great deal of elastin.

Healthcare professionals can help clients develop a program that addresses the specific strength goals. Typically, isometric exercises are limited in achieving strength, but there several situations when isometric is preferred.

Stress and “overload” exercises, such as isometric, isotonic and isokinetic, are used in strength building. Developing muscle strength takes hard work and determination.

When to use isometric exercises