In an interview with Empire Online, Joe Russo said of this scene,
He’s hanging onto that helicopter for an extremely passionate reason. In stories you’ll read where a mother will lift a car
off a child. There’s something very important happening in that scene
and for us it really represented his struggle as a character, one man
pitted against a helicopter that’s trying to take off. Can he stop it?
And what are the limits of his strength?
The
effects of doing this on Steve’s body depend on how much strain is
actually put on his muscles, ligaments, and bones. I don’t recall that
we’ve ever been told the full extent of his strength post-serum in the
MCU (as Joe Russo mentions, this scene is partly an exploration of
MCU!Steve’s abilities), but in the comics he bench-presses around 1,100
lbs:
This
seems about right, or maybe even a little on the low side, considering
his everyday feats of strength in the MCU, such as lifting a motorcycle
with three women on it in CA:FA:
And throwing another motorcycle at his enemies in AoU:
(Psst, Steve, motorcycles are supposed to stay with the wheels on the ground!)
In
order to answer your question, we need to know how much lift the
helicopter can generate vs how much force Steve can apply to it. I know
absolutely nothing about helicopters, but a Bell 429 (which is the
most “helicopter”-looking helicopter I could find on Google) has a cargo
hook capacity of 3,000 lbs, meaning it can take off with 3,000 lbs
suspended below it. So let us assume that Steve is in effect
“reverse-lifting” (pulling down instead of up) 3,000 lbs, which sounds
like a lot, definitely outside his normal capacity.
…Except he’s
not actually doing that, because (as far as I can tell from the
2-second clip) he doesn’t try to pull the helicopter closer to himself
(concentric force), he’s keeping it from flying away (eccentric force).
Because of how muscle fibres work at the molecular level, they can
generate 1.75 times greater force eccentrically than concentrically,
meaning that Steve (at least in the comics) is capable of lifting just
shy of 2,000 lbs eccentrically. That’s pretty impressive!
However,
it’s still less than the helicopter’s 3,000 lbs capacity, so how do we
explain that? Well, Steve isn’t actually pulling eccentrically at the
helicopter by the end of the clip, he’s just holding on to it,
generating static force. This means that his bones and ligaments are now
assisting his muscles to prevent his body from being dismembered. If
you’ve done any weightlifting yourself, you’ll know that your static
strength is much, much larger than either your concentric or eccentric
strength – I’m a total weakling so I can’t do an actual pull-up either
concentrically or eccentrically (feel free to laugh), but I can easily
hang from the pull-up bar, even one-handed, and let my ligaments carry
my full bodyweight with no ill effects.
I don’t know how strong
Steve’s bones and ligaments are, but considering he’s a supersoldier and
nigh on unbreakable judging by his propensity for jumping out of planes
and elevators, I don’t think he’ll suffer any debilitating injuries
from this helicopter stunt – maybe some strains and sprains, and even
so, I bet the movie will show him up and running again shortly
afterwards. 😉
So while it’s definitely impressive, holding down a helicopter trying to take off seems to me to be well within Steve’s
abilities (I was more impressed by the fact that he managed to lift
that steel beam off of Bucky during the fight on the helicarrier in
CA:TWS). Provided Steve can keep a grip on it, of course; helicopters
look pretty slippery. 🙂
To add some extra helicopter- and helicopter-adjacent details and discussion to @wintercyan’s awesome meta:
The situation is probably even more reasonable than @wintercyan lays out, because of the way that helicopters’ ratings are listed, which is a function of how helicopters are used for moving people around versus moving cargo around. [detailed discussion after the read-more!]
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