How water controls the speed of muscle contraction(phys.org)
phys.org
How water controls the speed of muscle contraction
https://phys.org/news/2024-07-muscle-machine.html
3 comments
It’s not clear from the article. Would something like creatine, considering it’s ability to increase water retention, positively or negatively impact the muscles speed?
Doesn't exactly seem like a particularly well-validated model at this point. Given they're saying muscle speed is limited by the speed at which water can move through the muscle, pushing more water through the same sized tube takes longer, so that would seemingly mean anything that caused greater water retention would slow you down.
But obviously that breaks down pretty quickly. You can't make yourself faster by dehydration. Your body maintains the water level it does for a reason. Catalysts and enzymes need to exist in specific concentrations to work best. Presumably, you retain extra water when taking creatine because creatine's role in catalyzing ATP production relies upon being at a specific concentration and more creatine means you need more water. But even if that excess water slowed down the maximum theoretical rate at which a muscle could contract, muscles that contract are also limited by the availability of ATP. If creatine is doing its job, then you'd have more available more quickly. You can contract faster with available energy than you can with no energy. You can't just isolate a single factor in muscle contraction and intervene in that without having other effects on the same complex, multifactorial process.
But obviously that breaks down pretty quickly. You can't make yourself faster by dehydration. Your body maintains the water level it does for a reason. Catalysts and enzymes need to exist in specific concentrations to work best. Presumably, you retain extra water when taking creatine because creatine's role in catalyzing ATP production relies upon being at a specific concentration and more creatine means you need more water. But even if that excess water slowed down the maximum theoretical rate at which a muscle could contract, muscles that contract are also limited by the availability of ATP. If creatine is doing its job, then you'd have more available more quickly. You can contract faster with available energy than you can with no energy. You can't just isolate a single factor in muscle contraction and intervene in that without having other effects on the same complex, multifactorial process.
Right, tell the hordes of olympic weightlifters, boxers etc deliberately losing water to make weight, that they should lift/fight at that depleted state. They'd probably collapse after the first lift/minute or cramp like crazy.
I think to tease this apart you need to know some things about muscle physiology. Which basically work by pushing billions (trillions?) of molecular motors in unison.
Energy wise, it's like... glucose is the coal of the power plant, ATP is the electricity shooting down the wire, and then you got creatine kinda acts like a short term battery or capacitator. So your egerny originates from the power plant (glucose) but is stored locally in the mucscle cell (creatine) So you eat a bunch of creatine, it's like building up your battery stores. Your mucscles got more battery means they got more lasting power.
The answer to your question is creatine increases muscle speed by increasing energy supply (not to do with water) in scenarios where lack of energy might otherwise insufficiently supply and thus slow down muscle contractions.
To the and wavey point of "creatine increases water retention" you have to think of the water retention *inside the cell itself* which is driven a lot by osmotic pressure (if you don't know what this is... git gud and come back). And the long and short of it is, if any funkiness happens water-pressure-wise in a cell (from osmosis typically), the cell either shrivels and dies (hypoosmlolar cell) or swells and eggsplodes (hyperosmolar cell). That is to say, the cell is either loosely iso-osmolar to the surrounding tissue, or it's dead. So taking a bunch of creatine isn't going to dramatically alter the H2O homeostasis of your cells given the need to maintain equilibrium and not die. Lest all the muscle cells die, cause rhabdo, die of kidney failure. I hope this helps. It's ompcomilcated
Energy wise, it's like... glucose is the coal of the power plant, ATP is the electricity shooting down the wire, and then you got creatine kinda acts like a short term battery or capacitator. So your egerny originates from the power plant (glucose) but is stored locally in the mucscle cell (creatine) So you eat a bunch of creatine, it's like building up your battery stores. Your mucscles got more battery means they got more lasting power.
The answer to your question is creatine increases muscle speed by increasing energy supply (not to do with water) in scenarios where lack of energy might otherwise insufficiently supply and thus slow down muscle contractions.
To the and wavey point of "creatine increases water retention" you have to think of the water retention *inside the cell itself* which is driven a lot by osmotic pressure (if you don't know what this is... git gud and come back). And the long and short of it is, if any funkiness happens water-pressure-wise in a cell (from osmosis typically), the cell either shrivels and dies (hypoosmlolar cell) or swells and eggsplodes (hyperosmolar cell). That is to say, the cell is either loosely iso-osmolar to the surrounding tissue, or it's dead. So taking a bunch of creatine isn't going to dramatically alter the H2O homeostasis of your cells given the need to maintain equilibrium and not die. Lest all the muscle cells die, cause rhabdo, die of kidney failure. I hope this helps. It's ompcomilcated
What do you mean die of kidney failure?
Look up Rhabdomyolysis and its effects on the kidneys.
Lot of paywalls lately, here is a preprint for this one
https://www.biorxiv.org/content/10.1101/2022.02.20.481216v3
https://www.biorxiv.org/content/10.1101/2022.02.20.481216v3
Tldr; other papers simplify muscles to the molecular level. This one explores how it acts as an engine in various contexts: human neuron contraction, insect hydraulic contraction, and shape of the whole fiber throughout the process.
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Interesting stuff
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Interesting stuff