What are isometric exercises? Simply put, they are a form of training that does not require any movement. When performing an isometric contraction, the joint angle and length of the muscle do not change. Isometric comes from the Greek word (not surprisingly) iso, which means “the same”, and metric, which means “length”. Even though there is no actual movement, tremendous force is applied that can result in huge gains in muscle size and strength. Isometric exercises have been a part of training methods like yoga and martial arts for thousands of years.

Isometric training works on the principle known as the “Synapse Effect.” This principle refers to the fact that the human body always strives to use the minimum amount of energy to do anything. So if you’re lifting weights, your body is constantly trying to use the absolute minimum of muscle fibers to move that weight. When you perform an exercise like the bench press, there is really only a split second where all the muscle fibers in your arms are used. This is why it is necessary to perform several sets and repetitions of an exercise when lifting weights.

However, with isometric exercises, this is not the case. By holding a static contraction, you are forcing all the muscle fibers to come into play for that particular exercise. This is not easy and requires tremendous concentration. A leading isometric training expert noted that the goal of this exercise is to “get to the last rep first.” This is a good summary of the isometric exercises that I have read.

To illustrate how effective this form of exercise can be, I want to tell you about the 1920 Springfield Frog Study. Here was the situation. At the end of World War I, the medical community had a problem. There were thousands and thousands of wounded soldiers who needed medical attention. However, there simply was not enough medical personnel or equipment to go around. There was real concern that with so many soldiers sick, they might lose the use of their limbs through lack of movement. How long could a limb remain immobile before irreversible atrophy occurred?

In an attempt to answer this question, the researchers assembled several frogs to test for this stunting problem. They took one of the frog’s legs and completely immobilized it, while leaving the other free. They left the frogs for two weeks, during which time they fully expected the bound, immobilized leg to wither away, while the freely moving leg was fine. Although that’s not exactly what happened…

However, to the astonishment of the researcher, the bound leg did not wither. To his astonishment, the immobilized frog leg became much larger and stronger than its freely moving counterpart. So much so, in fact, that when released, the frogs actually jumped lopsided! The researchers didn’t realize it, but they had discovered the power of isometrics and crunching. During the experiment, the frogs constantly tried to move their immobilized leg. They were using every muscle fiber to do it, giving him a tremendous workout. The free-moving leg didn’t have to do this, so it didn’t change much.

Isometric exercises are not as popular today as they were in the past, although they are still a fantastic form of exercise. I suspect one of the reasons for this is that although they seem easy to do, they are NOT easy to do. Performing an isometric contraction correctly requires complete concentration and maximum effort. Still, for those who put in the effort, the gains can be huge. If you are looking for a change in your training, you may want to try isometric exercises.