Let us now sidestep over to weight room where dumbbells are kept, and once again get in start position for a standing bicep curl with dumbbells. Notice term "standing". You know, like you DIDN'T do all day at work, and hopefully also did not do in your car on way to gym. So before we even start exercise, we are using more muscles than we did on machine - namely 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 muscles of lower back and spine. Now we are using our legs, our abs, and our back. Flex those elbows and start to raise 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 biceps are also in on action by this point, as are forearms, fingers, and shoulder girdle.

We now have dumbbells all way up and it's time to start lowering them again, via an eccentric contraction of biceps (also know as extending elbow). What muscle group controls extension of elbow? The triceps on back of arm.

Did you lose track yet? It's okay if you did because you have illustrated point:

Machine Bicep Curl: Uses biceps, forearms, and fingers Cost: Thousands of dollars

Standing Dumbbell Bicep Curl: Uses biceps, forearms, fingers, legs, abs, back, triceps, and shoulders. Cost: $40 for a good set of dumbbells that can be used for dozens of other exercises

In a nutshell, free weight exercises simply USE MORE MUSCLES than machines do, which make them more effective. Does that mean that machines are a complete waste? Absolutely not! In some circumstances it is BETTER to stabilize muscles being used in any given movement. However, those circumstances are exception, rather than rule.

So what do you do? Change up your routine, and incorporate free weights as well as machine exercises. However, keep machine work to a minimum - say 20% of your total time spent working with weights. Spend other 80% developing your stabilizer muscles, your sense of balance and coordination, and if nothing else - just standing up!

After all, you can go home and sit down on couch to enjoy your post-workout snack. The bicep machine already brought kids home from soccer practice, remember?