Working the chest: Pec Deck Flies vs. Dumbbell Flies

I hear debates in the fitness world about the pros and cons of free weights and selectorizers. Which is better?

I was doing some dumbbell butterflies at the gym the other day, and I thought it would be fun to look at dumbbell flies versus butterfly machines.

First, a description of the butterfly machine, also called the pec deck butterfly. This Web site describes it this way:

"Using a Pec Deck machine, seat yourself in it accordingly. Perform the exercise by squeezing your forearms and elbows in together so that you virtually touch them together at the peak of the movement. Be sure to really squeeze your pecs at the peak of this movement for a one-count. Return to the start position and repeat."

When I do dumbbell butterflies, I usually lay on a flat bench. You can also do them on an incline bench. Here is a description of flat bench dumbbell flies.

"Position yourself on a free-standing flat bench, flat on your back. Have your spotter hand you each dumbbell. When you begin this movement, you want your arms to be stretched out wide to your sides with your elbows slightly bent and your palms facing inward, toward one another. When you lift the dumbbells up together, visualize hugging a giant tree trunk. At the peak of the movement, really squeeze your pecs together for a one-count. When returning to the start position, be sure to lower the dumbbells in a slow and controlled fashion."

On this Web site are cute animated diagrams and descriptions of the butterfly machine and the dumbbell flies.

This article on about.com gives a good discussion of free weights vs. machines. Some of the pros of weight machines are: they're supportive, they're easy to use, they save time and they're less intimidating. However, they can be too supportive and limit the ways you can work your body.

The pros of free weights include versatility, functionality and building whole body strength. However, they can be hard to learn, there is more risk of injury, and they can be confusing.

Personally, I think there are benefits to both types of exercise, depending on what your purpose is. The dumbbell flies are more difficult -- as are most free weight exercises -- and they make me more sore. I try to do them most often.

But some days, I just don't feel like lifting the free weights, or the free weight area is too crowded, or I'm in a hurry, so the butterfly machine does just fine. The butterfly machine is also a great finishing exercise. If I have done several free-weight chest exercises and need one more to finish up, the butterfly machine is a great one to jump on.

Which do you prefer, free-weight butterflies or butterfly machines?