i was recently talking to an exercise phys major friend of mine who explained to me why her prof had stopped doing bench press of any kind. as far as i know using the chest fly press machine is a bad idea because it hyper extends your shoulders putting them in a vulnerable position. now from what i understand the same is true about the coveted bench press in all of its variations. it maes sense to me since you are lowering the weight all the way to your chest to get the full effect, does this make sense, or am being paranoid. thoughts? feelings?
Hi, deRaaf. Welcome to Gus and thanks for the post.
First of all, I, personally have no big love for the bench press and don't really feel it is necessary "in general" for strength development. Some people may have specific reasons for doing it or do it for competition but if you don't want to bench press I'm not here to preach bench press to you.
However a bench press done with good technique is not the same as a fly.
Let me get some technical stuff out of the way first. Everything I say here is referring to the shoulder JOINT itself which is called the glenohumeral joint. So what I mean here is the actual ball and socket joint that is your "shoulder". So the movements I'm describing are referring to the joint and not the shoulder "girdle" which is actually the scapula and clavicle and their articulations.
The reason I am pointing this out is that sometimes people start out talking about the shoulder joint but then they use movement terms that are actually referring to the shoulder girdle. Since those terms are not the same this creates a lot of confusion about basic shoulder movements. For instance, if I say "extension" of the shoulder joint that would actually entail depression and downward rotation of the girdle.
When you move the shoulder straight behind you, as in simply swinging your arm back from a position at your side that is simple SHOULDER EXTENSION.
When you bring your arm up from you side that is ABDUCTION.
The action of a fly is technically "horizontal abduction" but it is also sometimes referred to simply as extension or horizontal extension.
So you can see that even though I pointed out that a good bench press and a fly are not really the same there is a lot of room for confusion just in the terminology itself. Then when you factor in the various techniques people bring to the bench press and you combine that with the idea of hyper extension, etc…there is no telling what someone may be talking about exactly because you need to know first what they call the separate movements and second if they know how to bench press correctly in the first place. Not to insult exercise physiologist but not even all of them are really familiar with a good bench press, and frankly, strength development may not be their strong suit, depending on the individual.
The action of a "pec deck" like the one shown below or a typical dumbbell fly exercise for sure puts a lot of stress on the glenohumeral.
And if you bench press with your elbows flaired and a too wide grip to boot, as in the image below, you've got much the same problem:
Many very successful pros use a wide grip elbows flaired approach, as well. But it's actually known as a "bodybuilder style" bench press because the idea is that it targets the pecs more. So you can bench press with problematic technique and still be "successful" but in the long run the shoulders will be vulnerable to injury and it may be downright debilating to your lifting career.
However if you do not bench press with your elbows out like that and instead keep them more tucked to your sides at around a 45 degree humeral angle then it is much more friendly to the shoulders as opposed to a fly or a elbows out bench.
It is important also that you do not allow the arms to drift out as you complete the lift which is very easy to do. You have to maintain that good angle around 45 degrees from your torso.
To visualize this think of your arms right against your sides as zero degress. Your arms straight out in a dumbell fly position is ninety degrees. So the 45 degree angle is around half way in between that. It doesn't have to be exact of course! You don't need a buddy to measure your angle with a proctractor.
Here is a video with Eric Cressey dong a big bench. Take note of the angle that his arms keep in relation to his torso. His grip is fairly wide. Most people start with a grip that is a little more than shoulder width and go from there to find the grip that is most comfortable for them.