Hacker News Reader

Comment by gaius | Hacker News Reader

In a untrained person, at maximum effort you can activate about 30% of the fibres in a muscle. Not the same 30% every time obviously, that's just what your nervous system has the power to drive. In a trained athlete that goes up to around 50%. Now that's intriguing; if an untrained person could achieve full activation (say in a moment of dire need) they could more than triple their strength...

View on HN

> Now that's intriguing; if an untrained person could achieve full activation (say in a moment of dire need) they could more than triple their strength...

That one can and does happen. There are recorded instances of seemingly heroic strength where, for example, parents have lifted a car to rescue a child who was trapped underneath.

My research has led me to believe that only an adrenaline surge can produce this.

The thing to note about this is that it essentially impossible to not seriously hurt yourself when you do this. You will tear the muscles. They are operating at their highest power before the wheels start flying off, and you'll tear a lot of fibers.

That's called "recruitment". If you start weight training, your effective strength will go up fairly quickly for the first few weeks as your recruitment goes up; then it levels off (and at this point most people give up on training) as further recruitment slows and actual enlargement of the muscle fibers begins.

That is probably because the fibers are handing off work to each other like a baton race, "I'm pooped, take over for me". You might get triple strength - at the cost of sudden collapse a few seconds later when the whole muscle runs out of resources at once.

Edit: in this context, consider the muscle prostration of a person who has been tazed (which forces total contraction electrochemically).

Yeah, that would happen when the ATP was fully converted - so 5-10 seconds.

t-nation.com reckons it's related to nerve signals rather than individual fibres tiring tho'.

Reply on news.ycombinator.com