An arm blaster is a piece of exercise equipment that helps to isolate the biceps during arm curls. It became popular during the 1970s because Arnold Schwarzenegger used it to help build his biceps during his run as a seven-time Mr. Olympia. The arm blaster is a kind of harness that an athlete wears on the upper body to lock the arms into the correct position during arm curls. The arm blaster minimizes the body's ability to perform arm curls using improper form and thus maximizes the benefit of the arm curls for the biceps muscles.
It is often difficult for athletes to maintain proper form when performing arm curls without an arm blaster. It is common for an athlete to allow the elbows to flare out or to use the lower back and shoulder muscles to contribute to lifting the weight. Athletes also tend to rock during arm curls, and this allows the athlete to lift the weight using momentum rather than placing all of the weightlifting strain directly on the biceps muscles. Not only does this increase the risk of injury to the athlete, it also prevents the biceps from receiving as intense a workout as they would if the athlete maintained proper form. This, in turn, limits the amount of growth of the biceps.
The arm blaster makes it difficult for an athlete to perform arm curls without proper form and thus increases the overall benefit of the exercise for the biceps muscles. To use an arm blaster, an athlete places a fabric strap around his or her neck. The arm blaster hanging at the ends of this strap consists of a piece of curved metal. The shape of the metal allows the arm blaster to lie against the upper abdominal muscles. At each end, though, the device curves so that if an athlete's arms are at his or her sides, the metal will slip between the body and the arm and then curl around the back of the triceps.
This design forces the arms to remain locked in position during the lift. When an athlete begins an arm curl, the weight will press the upper arms against the metal. This, in turn, presses the metal against the upper abdominal muscles, and thus the arm blaster will not move during the lift. The arm blaster remains in place, so the upper arms must remain in the proper position as well. Also, because the metal wraps around the triceps, it is impossible to flare the arms to the sides while wearing an the device. As a result, all of the strain concentrates on the biceps, and they receive a very intense, isolated workout.