For those here that use flyes as a chest exercise (or the conscientious objectors to flyes), I have a question. Are dumbbell flyes effective for developing size and/or strength in the chest as the movement comes closer to the “top”? I always saw flyes as a movement utilizing the pectorals that emphasized the function of bringing the arms together across the body (for competition clapping maybe?). If that’s the case, then when you start flyes while lying down, it seems like an effective exercise, but the closer you get to the top, shouldn’t the “horizontal” effort required to bring the dumbbells together approach zero? At the top (~ straight above your pecs) you should be pushing away from you, not bringing your arms together, considering the direction of gravity relative to the position of your arms. I always saw cables as a way to constantly apply force in a horizontal (i.e. bearhug) manner. Should one do flyes lying on their side (awfully awkward)? What are your thoughts?
Having completed first year college physics, I can with confidence say that when you’re doing flyes while lying on your back, you’re going to get the most resistance when the flyes are completely horizontal. Since the shoulders are the pivot point, at the top of the movement, the force on the muscles is almost zero, since the force is directed through the shoulder.
If you’re using cables, the cable is going to pull at the maximum force horizontally, no matter where your arms are, so it would seem superior to the dumbell flyes in that respect. Keep in mind that using the cable provides no vertical push. I’m not sure what the effect of that is, but since you’re trying to train your pectorial, I’m guessing it wouldn’t be detrimental.
I’d suggest you do flyes with cables while lying on your back.
Why would lying on your back as compared to standing change anything for cable flyes? Wouldn’t the resisting force always be pulling along whatever line the cable was making from the final pulley to your hand? Just curious. I’ve always just used cables for flyes when I do them for this reason, and that dumbbell flyes never “felt” effective, but I have recently started trying to do the dumbbell version.
The only advantage of the dumbell fly in my opinion is the superior stretch at the bottom of the movement. As you explained the movement gets easier as you go. This means that you can handle much more of a load then the cable flys. If you tried to get the same amount of tension at the begining of a cable fly you would not be able to complete the set. So in my opinion they are a superior excercise if you are trying to get a good high tension stretch at the bottom and a worse exercise if you are going for constant tension. They both have a place. Anyone disagree?
Just don’t come all the way up when you’re flying. Only bring the dumbells up to the point where the tension in your pecs begins to decrease. Problem solved.
So is the consensus that the upper portion of the dumbbell flye is useless for its intended purpose? I guess another problem is trying to find more of a free weight solution for the fly movement. (Cables don’t require the same balance.)