Increasing muscle power without increasing volume
Some of you may know my mutant thread, and guess what? It's back.
I'm wondering if there is any biological means to improve muscular power without greatly increasing the volume of said muscle.
My conundrum is that I have some mutants easily able to lift 6 tons (and more - as in lift above their head and carry around), but that look like normals, albeit athletics, humans. On the other hand, the human world record for bench-pressing is around 320kg1 and the holder is already humongous.2
Is there any way (apart from handwavium) to increase muscle power and retain a normal human shape?
What I'm looking for/How I'll rank answers:
- Only biological, science-based explanations please. No mechanical augmentation, something that can reasonnably happen inside a "human-ish" body (so please, no nuclear fusion to power your super muscles).
- The energy expenditure is overlooked, but other factors such as resistance (to avoid this person tearing itself up) would be nice.
- If it's not possible, explaining why would also help.
1: From the top of my head, feel free to correct me if there is any mistakes.
2:And yes, Batman bench-pressing 1-ton is clearly inhuman, stop pretending this guy is not a mutant in some way.
Addendum: Of course, lifting capacity does not equal strength. But it is hard to exactly describe the physical raw power of someone. Lifting is used here as a common denominator for everyone to just show the order of magnitude involved.
This post was sourced from https://worldbuilding.stackexchange.com/q/151072. It is licensed under CC BY-SA 4.0.
1 answer
Yes, there is likely a way, though I will admit I'm not sure how much of the desired about 20x difference it will get you. By the time you get into those mass ranges, the strength of the bones, tendons and attachments will likely be as important as, if not more so than, the muscles themselves. Also, as Spoki0 pointed out, technique matters.
That said...
Give them more fast-twitch muscle fibers, and less slow-twitch ones.
See for example How chimps outmuscle humans.
Slow-twitch muscle fiber (myosin heavy chain I) are better for endurance tasks, while fast-twitch muscle fiber (myosin heavy chain II; in the case of chimpanzees, specifically type IIa and IId) come at a higher energy cost and are better for speed and short-term force. As stated in the linked article,
The researchers found that whereas human muscle contains, on average, about 70% slow-twitch fibers and 30% fast-twitch fibers, chimpanzee muscle is about 33% slow-twitch fibers and 66% fast-twitch fibers.
By running simulations, it was found that this difference of slow-twitch vs fast-twitch fibers resulted in an overall muscle which was 1.34 to 1.35 times as powerful, depending on the exact metric. The researchers performing the study concluded that
These results suggest that the larger fraction of MHC II fibers and the longer muscle fiber lengths characteristic of chimpanzee skeletal muscle will increase their dynamic force and power-producing capabilities overall.
and that
Although our simulations do not reproduce the earlier experimental designs in detail, the close approximation of our results to the 1.5 times average suggests that muscle mechanics"”MHC isoform content, in particular"”accounts for much, but not necessarily all, of the measured chimpanzee"“human performance differential. Muscle "static strength," defined as maximum isometric force-producing capabilities (Po), is not significantly different between these two species and therefore does not contribute to their performance differential[.]
Therefore, it stands to reason that by tweaking the muscle fiber composition to favor type II, and by increasing the length of individual muscle fibers, you can increase muscle power without a corresponding increase of muscle volume, but at the cost of muscle endurance.
As pointed out in a comment by Yakk, you can also take this even further by giving them even faster and longer muscle fibers than humans' long type II muscle fibers. You will hit a limit at some point, but as pointed out, it's definitely possible to give your creatures even more strength per unit muscle mass than humans' type II fibers allow, and you can probably maintain suspension of disbelief taking it at least one step further, though again, you're making a tradeoff against endurance.
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