Effects of a Different muscular Fiber structure

Question

So my society can genetically engineer using Retro-viral vectors specially designed to work on only the subject they are injected into. I wanted my police force to be locked in a struggle with organized crime syndicates who are selling illegal weapons grade gen-mods to street thugs, gang-bangers, and bored college frat boys.

While dreaming up various mods like IR vision, hyper efficient metabolism, etc etc I ran into a question I really cant seem to find an answer for. What would the benefits be of muscle fiber tissue that forms a spring like coil structure around a core of regular muscle fibers?

Answer 1

What would the benefits be of muscle fiber tissue that forms a spring like coil structure around a core of regular muscle fibers?

Little to none. But if I understand what you're after, you can get it another way.

First of all muscle is not enough. Muscles are already strong enough to break bones if they contract really hard (e.g. tetanus contractions or displays of hysterical strength). So your first objective is to reengineer the bones, which is going to be difficult (on a grown up you can perhaps sacrifice some marrow). Your new osteocytes must provide both hard fibers (carbosilicate compounds are harder than bones) and organic bonding agent. Basically you're remaking the bones using organic Kevlar, and it will take anywhere from six months to several years. Metabolic expenditure to achieve the six months goal is going to be huge, and you'll develop an appetite for sand.

Once this is done you can get a six-fold increase in muscle power almost for free (in the short period). It turns out that human muscles potentially are already much stronger than they could be, at the cost of possibly damaging themselves (that's why a common outcome of psychomotor agitation is rhabdomyolisis, or muscle death); they're simply tuned for precision and endurance instead of power, with a majority of myosin-heavy chain II against I. Reverse the proportions and you get an "instant" 30% boost in strength, even if you'll fatigue faster. Then the innervation is tailored for precision; changing the nerve structure so that you can get both stimulation and control will probably(?) require developing peripheral ganglia inside the larger muscles to control power, so that you have "hysterical strength" available on demand but still retain precision control, and do not need an adrenaline flood to trigger gear shifting but can do so at will.

At this point you've killed the patient anyway: he won't break his bones, he won't get rhabdomyolisis, but now his muscles will consume six times as much oxygen and glucose, and possibly produce six times as much lactic acid every time they switch to "Power Boost". You need to either reengineer hemoglobin or reengineer the arterial tunica, venous valves, heart and lungs to withstand 6X bursts. Or you need to deploy oxygen and glucose reserves - or directly an adenosintriphosphate analogue - locally. In this case you'll get a short (or not so short) powerful burst, followed by a long refractory period while the reserves recharge.

All the above presume an organic approach. You can go down the cyborg way (but not, I think, with a gengineered virus - you need nanites to do this) and supply parallel electromagnetic muscle fibers. You still need stronger bones, and you still need a refractory period to recharge the cybermuscles' batteries.

Answer 2

I think it would make no sense: let's call the regular fiber A, and the spring one B, arranged like a solenoid.

When a motion has to happen, fiber A shall contract. Normally this is opposed only by the resisting load applied to the muscle, and the movement can be reverted by actuating the antagonist muscle (like triceps and biceps in human arm).

In your case instead together with the resisting external load your fiber A has also to overcome the resistance of fiber B, and has to be kept engaged as long as no spring back is needed.

Apart from the obvious inefficiency of exerting an effort while contemporary resisting to it, which is kinda inefficient, while normally if you flex your biceps you relax your triceps, this would require a complete redesign of the muscular disposition on the body (antagonist muscles no longer needed) together with a rewiring of the brain parts dedicated to motion control.

(Retro)virus cannot change a body architecture. You would need dedicated evolution for that.

Answer 3

Probably not what you're thinking.

First of all, let's talk about what this structure would do. Normal muscles are functionally composed of actin and myosin fibers that slide along each other to make the muscle cell shorter and thus cause contraction. When enough of these cells are aligned and synchronized, you can have powerful movements. However, your musculature is not aligned, so this additional band isn't pulling with all the other muscles and is actually pulling across them. Shortening a helical structure wrapped around a tube will compresses the tube. This actively works against the contraction of the muscle as a whole, because the rest of the muscle is trying to get shorter and wider and your filament is trying to force the rest of the muscle to be thinner and longer.

This is conceivably useful if the new muscle was triggered to relax when the rest of the muscle is contracting and if the new muscle was triggered to contract when the rest of the muscle is relaxing, because it would facilitate a return to normal and reduce the amount of pairing that muscles require.

Now, it sounds like you're actually hoping to have spring-like behavior. You won't get that from muscle cells because they don't have any native restoring force. If you drop a slab of meat on the ground, it doesn't bounce at all for precisely this reason- it's relatively fine with being deformed. Our muscles return to their original positions either because it's energetically favorable (e.g. letting your arm drop after holding it out horizontally) or because we have a muscle pulling in the other direction (e.g. doing push-ups).

In fact, very few biological cell will cause a true spring-like behavior, even if coiled into a spring shape. Perhaps cellulose would work, or some other structural protein like chitin. I don't know of any human cells that would display this trait.

However, if you're handwaving that part of the problem as well, it's still a bad idea. If you suppose that we have actually found a biological structure in humans that stores energy like a spring, it really won't be that helpful. As L. Dutch points out, it's nice to be able to do things without always having an opposing force resisting that movement. To get an idea of what this would feel like, try wearing a wetsuit. The neoprene has a preferred shape and will weakly pull your limbs back into position. It's an eerie feeling, and you'll see many wetsuit-clad surfers or divers walking around with their arms held slightly out from their sides because of this behavior. Wearing a wetsuit makes it more difficult to do anything besides stand still, allowing the neoprene to take the shape it would prefer.

Answer 4

A "spring-like" muscle, assuming you intend to have it work like a steel coil spring, would be useful for prolonged activity working against gravity, like in your legs. The central normal muscle fiber serves to compress the muscle spring and hold it for explosive release of the stored compression energy, but it is very difficult for ATP based actin muscle fiber to stay contracted for very long, so this spring muscle is really suited for a springy bouncing gait of walking/running. This is using gravity (and your own bodyweight) to help compress the spring, the central muscle mostly just holds it for a brief time while you move your leg, then it relaxes and lets the spring propel you along. So a creature with this structure would have an easy time running, letting gravity do most of the work, but would find moving slowly very fatiguing, since then he would be relying on the central muscle fiber to delicately control the spring muscle.

I don't think this type of muscle would be very helpful for core or upper body activity, since it wouldn't be well suited for fine motor tasks or working with an opposing muscle system just to hold you upright, for example. I'm also not sure how easy it would be to create an organic springy material to replicate memory steel but that can be handwaved.

Answer 5

The spring part is useless. Coiling the muscle fibers themselves would provide benefit. Muscles are around 25% efficient. Excessive myosin and actin overlap is the cause of this waste. By coiling the fibers you not only increase fiber length within a given volume but also increase efficiency. About three times the efficiency. I'm unsure exactly how much stronger it would be. My guess is around 1.5 times as strong as a normal fiber.

ATP production is typically 30% efficient but it can go as high as 90% efficiency at full load. So if you just tweak that you can get a total of 9 times the efficiency. That's a big boost to stamina.

Muscle moisture is around 80%. Halve that to 40% and you get double the density.

2*1.5=3. So 3 times the total maximum force output per cross sectional area. At 9 times the efficiency.

As others have mentioned our muscles are intentionally limited to prevent injury. Stronger thicker bones, thicker tendons, rapid regeneration all significantly help with that. Not just healing. Healing leaves scars. Actual regeneration axolotl style is needed or else your muscles will have so much scar tissue they'll barely be functional.

The last thing is a maybe. Im currently researching it, but I don't yet know enough to give you an answer. If muscles can be made to actively extend the same way they contract then you can get a higher volumetric strength by having the upper arm bone surrounded by a tube of muscle. Perhaps with hollow tendons filled with hydraulic fluid, this can be used to push and pull.

Even if that doesn't work, a tube will use up more space then a biceps triceps setup, just calculate the total force and divide by 2 for the extension bit.

Tldr coiling muscle fibers increases surface area which enhances efficiency and strength. Same thing for coiled artificial electroactive polymer muscles.