I agree OP it doesnt make sense, you should usually be able to do more with a BB than a DB. Maybe because of form on DB your utilizing other muscle groups more than you do on the BB. I have no idea. Form is all I can think of here. Do you grip the DB the same way you gripped the BB? Palms out? I see some people going palm in on DB OHP/Shoulder press.
It is a pretty loaded DB so it is a parallel grip. I am wondering if it could be because I need to figure out which grip is good for me. Maybe a shoulder width might be better as it will mimic closer to my normal press. With sandbags and other objects its all shoulder width.
Couple things come to mind.
First, you are trained in single arm ohp. The motor programming is developed. If you don't do double arm ohp often, or this is the first time, then it will take time to develop that motor programming; as you do your strength will increase in that exercise quickly (neural gains).
Second, what do you do for db ohp with two arms at once?
Personally, i can db ohp more using one arm at once then both arms at once. I can also dumbbell ohp about 75% of my military press in one arm.
Finally, are you using your lower body at all to drive the weight up? If you are, then its only to be expected that you will be able to do more in one arm then two at once, since you are using bilateral lower body musculature either way, and you aren't using more when doing both arms at once.
So I have a meet in October 2 ( i know long ways away) I really do not want to have to start training on a barbell until it is really needed. Its a 200lb axle for reps. I already train thick handed OHP also so I'm not worried about the axle I'm mainly worried about nailing it for reps.
So its probably a question of motor programming, and not strength.
Here's a rough outline of what I would suggest if I had a client in your situation:
Transition into standing bilateral dumbbell overhead press sometime in april.
Deload and transition into standing barbell overhead press sometime mid june
Deload and start working barbell push press and jerks sometime mid-late august.
I was thinking about this all day lol, and I started thinking about what rosie said, and about the stabilizers. Could it be that the stabilizers are actually helping doing the work more, than to where as on the BB its more of a concentrated muscle group? Less muscles to push the weight up?
Interesting about the motor programming Zir. Hey does it really take about 1000 reps to change motor programming?
Good question, and to be honest, I'm not sure. A few factors would come into play:
Is it learning a new skill, or trying to change poor habits from an old skill?
How ingrained is that old skill?
How coordinated is the individual?
I always remind my clients and other fitness professionals I consult: practice does not make perfect, perfect practice makes perfect.
Fatigue and skill enhancement are negatively related. The more fatigue, the less (or even counter productive) the skill enhancement.
That's why most good coaches have specific workouts: high skill motor movements (ie: power exercises snatch, clean etc; skills throwing a football, pitching, punching, kicking, takedowns, agility or acceleration) with sufficient rest; or, low skill movements with insufficient rest for conditioning.
Like ZIR said, definately has some to do with motor control that will adjust as you perform the exercise more.
Also, the biomechanics are slightly different when using a bb compared to dbs. You place more emphasis on the front delts with a bb because of how you lower the bar in front of your face, where as with db the weight is distributed more evenly across the three heads.
Either way if your competition involves overhead barbell presses (with an axle or whatever) then that is what I would begin training for as well in advance as possible.