First of all, a “Smith machine” is a piece of exercise equipment. Some people may be excused if they confuse it with all-in-one exercise machines, such as those manufactured by Bowflex, Body Solid, and Gold's Gym. While original versions were rather simple and were often built by do-it-yourself exercisers, modern versions may be constructed in configurations which can seem a bit confusing.
Originally designed by fitness expert Jack LaLanne, and improved by health club manager Rudy Smith, who then installed it in his gym, the basic Smith machine consists of a vertical rack which allows a barbell to be lifted and lowered between two guiding uprights. It is fitted with a series of slots on which the barbell can be rested during or after repetitions.
Exercisers doing lifts such as bench presses or squats with heavy weights can simply hook the barbell on the slots rather than having to have a spotter take it from them or go through awkward gyrations to re-rack the weight on a support themselves.
Many consider using the Smith machine to be a safer way of doing exercises with heavy weights due to this feature. Many also believe that the manner in which the lifter is forced to perform each exercise encourages a more precise form than exercising with free weights. Some also feel that, especially since the exerciser is somewhat protected from some injuries they might achieve more by using heavier weights than they might otherwise.
However, many others feel that the restrictions imposed by the equipment detracts from the results which might be achieved. This is commonly assumed to be because of the restrictive nature of the Smith machine itself. They feel that with free weights, the exerciser is having to move and control the weight through a “full range” of motions. This creates a very real drawback to using the machine as it is difficult, if not impossible, to achieve perfect form.
However, while some are concerned with form, many others are concerned with performance. You might be wondering if using a Smith machine will allow you to become stronger.
Testing as to whether exercise with or without a Smith machine is more effective is not as much inconclusive or conclusive as it tends to show that every sort of exercise and exercise equipment has its own strengths and weaknesses. Some exercisers achieved higher levels of progress in some exercises with the machine than with free weights. However, some achieved higher levels with other exercises with free weights than with the machine.
In short, a Smith machine can be an important piece of equipment when it comes to safety, but probably needs to be only one piece of equipment among many in a home gym or commercial gym.
Most home exercisers will not need a Smith machine and should be able to get excellent results in health, fitness, and weight loss with very simple pieces of equipment such as free weights (i.e. dumbbells, barbells, and kettle bells), all-in-one exercise machines, or even bodyweight exercises.