Smith machine
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The Smith machine is a piece of equipment used in weight training. It consists of a barbell that is fixed within steel rails, allowing only vertical movement. New variations allow a small amount of forward and backward movement.[citation needed] A Smith machine often includes a weight rack in the base to help stabilise it. Some Smith machines have the barbell counterbalanced. The machine can be used for a wide variety of exercises such as a squat shown in the image to the right.
Origin
The Smith machine was invented by American Jack LaLanne, who rigged up a sliding apparatus in his gym in the 1950s.[citation needed] It was spotted by men's bath house manager Rudy Smith, who commissioned Paul Martin to improve it[citation needed]. Smith then installed the improved model in a gym he was managing at the time, Vic Tanny's gym in Los Angeles.[citation needed] By the end of the 1950s, Rudy Smith was an executive in Tanny's chain of gyms, and the Smith machine was being manufactured and sold more widely.
Rudy Smith died on July 5, 2010. At the time of his death he was Chairman of the Board for the Las Vegas Athletic Clubs.
Use as a self-spotting device
Behind each vertical post (runner) is a series of slots on which the barbell can be hooked. This means that unlike an ordinary barbell, the Smith machine need not be re-racked after a set of repetitions: it can be secured at any point. This makes it safer for those who lift without a spotter, as one only needs to twist the wrist in order to lock the barbell in place in the event that the weight becomes too great. Most models also incorporate blocks, pegs, or other devices which can be adjusted to automatically stop the barbell at a predetermined minimum height.
Unlike a free-weight barbell, the bar on a Smith machine does not move forward, backward, or sideways. Because lifting on a Smith machine requires less stabilization by the lifter, lifters can usually lift more weight on a Smith machine than on a free-weight barbell. However, regular use of a Smith machine without supplementation with free-weight or body-weight exercises may result in muscle imbalances, poor development of stabilizing muscles, and a potentially higher risk of lifting-related injuries.
Research
Schwanbeck et al. reported that free-weights caused 43% more activation of the muscles measured than a Smith machine.[1] Men's Health reported that the straight motion on a Smith machine is an unnatural movement that stresses the knees and lower back. Men's Health also reported that traditional squats produced 50% more muscle activity in quadriceps compared to squats done on a Smith machine.[2] Although training with free-weights offers benefits that Smith machines do not, the superiority of free-weights over Smith machines may be overstated[citation needed]. The existence of Smith machines can be justified by the fact that they are often utilized as platforms for performing strength exercises such as the pull-up, chin-up, and inverted row.