Bicep Curl Machines
If you aren't familiar with old fashioned biceps curls, they're basically performed standing up straight with your palms facing forward, and a pair of dumbbells held down at either side of your body. As you contract each bicep you bend your elbow, bringing the dumbbell toward you at shoulder level in a series of repetitions.
Even though a bicep curl machine is based on this fluid movement, many would argue (myself included), that a bicep machine takes away the need for your other muscles to serve as support during the exercise.
Here, I'll explain. On a bicep curl machine you sit down, brace your upper arms on the machine's pads, grasp each handle and flex your elbows as you bring the handles toward your shoulders in an upward motion. You can probably already see, without my observation, that by using the bicep curl machine you're only working your biceps first because you're seated and second because your upper arms are supported by the pads without the need for any support from those secondary muscles.
Now wait one second before you get your gym shorts in a knot! I'm not by any means snubbing the benefits that a bicep machine can offer. If you're a beginner and you work out in a gym a bicep machine can be a great way to get your form down pat before potentially hurting yourself with free weights. Same goes if you're recovering from any lower body or back injuries. However, if you're planning to purchase a bicep curl machine for home use, it can set you back a couple thousand dollars and only target your biceps get my drift. It's all about the bang for your buck.
If you performed the same biceps curls standing with a set of dumbbells (which would cost approximately $50 for a set in the classifieds) the added benefits to your lower body are clear before you've even started the exercise. In addition to using those leg muscles that have been cramped under a desk all day, your dumbbells just added that much more weight to your frame. To control your center of balance your body is forced to support this additional weight by using the muscles in your abs, lower back and spine. Now instead of simply working out our biceps we're using our legs, our abs, and our back and that's not to mention the workout your forearms, fingers and shoulders are getting without having pads to lean on for support.
This doesn't mean that weight machines are a complete waste of money, but it is food for thought if you're aiming to get serious about weight lifting. A set of dumbbells will not only work more than one muscle simultaneously, it will force you to learn proper form using a lighter weight before you can graduate to a heavier weight. In cases where you have lower body or back injuries, or if you're specifically aiming to stabilize your biceps muscles, then perhaps a biceps machine is worth its weight.
