Anyone who has ever been in a gym before is familiar with the gleaming banks of shiny exercise machines. Coming in all shapes and sizes, they are usually cause for the newcomer to the gym to pause and ask, "What IS all of that stuff?"

Well, according to the price that the gym paid for any one piece of that equipment, I certainly hope that it not only stimulates your muscles, but also cooks your breakfast, washes your car, and brings the kids home from soccer practice! Now the question becomes whether or not those machines were worth the price, or if you'd be better off doing a home aerobics video with a can of soup in each hand….

Personally, I would advise you to get the low-sodium version of the soup, serve it up alongside a tomato sandwich, and then go buy yourself some free weights. Yes, that is just my opinion, but it does come with some scientific reasoning behind it.

Natural movement vs. Controlled movement

One of the things that you need to remember is that when you are exercising, you are training for LIFE. You may spend an hour a day at the gym, but that still leaves 23 other hours for your muscles to function without the aid of that fancy equipment.

Whenever you do any given exercise, the movement of your body during that exercise is called the Range of Motion. The greater and more difficult the Range of Motion, the more effective the exercise is, because your body has to work harder to perform that movement.

Let's take a classic dumbbell bicep curl for our case study. If you aren't familiar with the movement, it is basically performed by standing up straight with your palms facing forward, and a pair of dumbbells held down at your sides. You concentrically contract your biceps (also known as flexing your elbow) to bring the dumbbells up to approximately shoulder level, and then repeat the movement for a prescribed number of repetitions.

Let's take that same muscle movement and do it using a bicep curl machine. You sit down, brace your upper arms on a pad, grasp 2 handles that are in front of you, and do that same fancy elbow flexing movement to move the handles in an upward motion. Pretty easy stuff so far, right?

Now let's examine the muscles that are used in this motion. Wait – I thought we were concentrically contracting the biceps? That is correct, and if you are using the bicep curl machine, that is pretty much ALL you are doing. For one, you are sitting down. You know, like you did all day at work, and then in your car on the way to the gym. Then, your upper arms are braced on a nice soft pad to keep your upper body stable while you pull the handles upwards. The machine has effectively limited the muscles used in this exercise to the biceps, as well as the muscles in your forearms and fingers as you grip the handles.

Let us now sidestep over to the weight room where the dumbbells are kept, and once again get in the start position for a standing bicep curl with the dumbbells. Notice the term "standing". You know, like you DIDN'T do all day at work, and hopefully also did not do in your car on the way to the gym. So before we even start the exercise, we are using more muscles than we did on the machine – namely the leg muscles.

Now let's pick up a 10 lb dumbbell in each hand. We've just added 20 lbs to our body weight. What is keeping us from losing our center of balance and falling clean over? The abdominal muscles and the muscles of the lower back and spine. Now we are using our legs, our abs, and our back. Flex those elbows and start to raise the dumbbells. Now our center of gravity has become a fluid state, and our legs, back, and abs all have to constantly compensate to maintain posture. Oh, and the biceps are also in on the action by this point, as are the forearms, the fingers, and the shoulder girdle.