Resistance machines are pretty popular these days. Most gyms I walk into have machines as far as the eye can see – ranging from the Smith machine to the ‘pec deck’.
What do these machines do?
Well, these resistance machines were designed to allow the user to perform an exercise on them that they would normally have to do with a free weight. In other words, they copy a particular exercise and let you only perform that exercise on it. For example, take the squat.
The squat works by lowering yourself from a standing position to a squatting position, and back up again. This involves bending at the knee, and at the hip. A leg press machine lets you sit in it and push against a platform which has resistance and also basically the same muscles. This means using the leg press machine instead of squatting is OK, right? Nope. And I’ll tell you why.
Machines usually only let you move along 2 dimensions, e.g. left to right, up to down, backwards to forwards. In this example the leg press only lets you push off the platform and slide the seat backwards and involves the basic muscles groups that the exercise it copies would need, which is the squat. The squat requires much more effort and different muscles as there is not only movement up and down, but forward and backwards motion can occur if you don’t control how far you lean forwards, left and right motion can occur if you are imbalanced; basically you need a lot more smaller muscle groups in order to perform the exercise properly (which also means more energy will be burned as a result).
The difference between the two could be compared to cycling. Many people learn to ride a bicycle by attaching stabiliser wheels so that they can’t fall. These small wheels balance the bicycle meaning you don’t have to. If somebody who has only used the bicycle with stabiliser wheels tried to use a normal bicycle, it’d be like learning something completely new as they would have to use a lot more control than before. The same thing goes with machines and free weights.
Because machines do not let you move freely, they sometimes have you move in unnatural ways. Think of the Smith machine. You can use it to squat as you would with a barbell. But the Smith machine only lets you move in a straight line up and down, whereas if you were to use a barbell your natural movement might be different. Because you do not need to balance the weight, your entire body position becomes less important, which means you could do the exercise with very bad technique and still think you’re doing it correctly.
The same thing happens with other exercises. Think of the bench press. The machine that imitates this exercise lets you move the handles up and down, whereas the bench press requires a lot of balance and control. To move the machines handles up and down, you would only need to push away from your body, it wouldn’t matter if you pushed slightly towards your left side, or at a 80 degree angle; the handles would still go up. If you did the same thing on a normal barbell bench press, you would drop the weight.
The Good Points
There are some good points of using machines e.g. when performing exercises such as lateral raises, an alternative would be to use a machine with a cable and pulley system that lets you pull a handle from a low position. This way you can move along the same path as you would with a free weight, the difference is that there will be resistance along the whole path whereas using a dumbell you have the most resistance at the top of the exercise and the least at the bottom.
While there are some uses for machines, such as for isolation exercises of smaller muscles, you would be better off sticking to free weights for the majority of your exercises, especially the main ones.