My body seems to produce power of 100-200 watts on a stationary bike.
Given that horsepower is defined as 750 watts, I’m pretty impressed with myself.
(A Macbook apparently needs around 30 watts. So I just need to plug in and comfortably run it.)
The downside: as far as I can tell, I generate most of the power from hip flexors, which is exactly the opposite of what I need.
Down on the subcellular level, the muscle contractions are mediated by these beautiful actin filaments
(I wonder why colored electron microscopy hasn’t evolved into more of an artform – it is so pleasing.)
From Radical Abundance:
Consider the protein machines that move your muscles. These consist of myosin molecules that take steps along actin fibers, each step moving forward by thermal motion. If we were to peer through our nanoscale lens at a leg muscle in the midst of a macroscale step, we would see myosin molecules thrash in a blur, moving forward in nanoscale steps seemingly by happenstance, with energy from ATP molecules applied, not to drive steps forward, but to prevent steps backward.
Here’s a nice video of that process:
It’s nice to remember that we didn’t always know how muscles contract, or what role signals from nerves play in the process.
Before Volta’s experiments, it was thought that nerves were hollow and inflated the muscles by air – so-called “balloonist theory”.
Today, this sounds funny, but my primary reaction is that I am impressed with the scientists (“natural philosophers”) who came up with a relatively plausible mechanism just by observing how the fibers are connected.
Somewhere in the model, according to Wikipedia, was the idea that that muscles expand by the reaction of animal spirits with vital spirits.
The final blow for these theories was Galvani’s 1791 experiment showing that frog muscles contract when exposed to electricity.
By the way, you can apparently make a 2.5V battery by stacking layers of copper, potato and aluminum and use these to get some animal spirits flowing into a cockroach leg (see video).
It’s interesting to realize that this actually felt like an explanation of why muscles move to all of these smart folks.
Where are we invoking similar explanations today?