Have you seen any actual peer reviewed studies that supported that idea?
No, but then I'm a reasonable person. I wouldn't want a 5' 6" male 135 pounds trying to carry my 6' 1" 265 pounds either. But I have learned respect for female pilots who can take higher G forces than a man and operate under stress for longer periods of time. I have respect for a UAV remote female pilot who places the cross-hairs of a missile on a vehicle and blows the occupants away without a second thought. They do both those jobs as well as any man. If we were still fighting with swords and rocks I would agree with dissenters on this thread but war has evolved. The warriors have also evolved. Try determining which on-line gamer is male and female sometime based solely on their technological skill.
Good point. The upper-body strength tends to revolve around the twin unsupported assumptions that all men in the Armed Forces are He-Men and all women are pale slips of daintiness who meet only the minimum standards set by their services. And also that any time a soldier is wounded and non-ambulatory, the only other soldier available to evacuate them will be that waif. It's an appeal to probability, but I think it has more to do with gender roles than actual probability.
The "hand-to-hand combat" argument has me scratching my head, too. I'm sure it happens from time-to-time, but aren't most soldiers issued firearms?
There are other arguments against women in the military and naval services, and some of them are a bit more pragmatic. But I don't think the strength one, as usually argued here, is a very good one.