how long does it take for muscles to atrophy
 

I took a physical health class a few years ago and I somewhat remember that it said that it takes only a weeek for muscles to start breaking down for lack of use. How accurate is this?

about 2-3 weeks.

I can notice a difference after only a few days. Usually after anything longer than three days, I can feel the difference when Im out on the bike. Nothing drastic until a week though. Two weeks, and its almost like starting over, except I regain the lost ability much faster than had I been starting from scratch.

It depends on what you mean by lack of use exactly. If you take it to the extreme it means putting people on absolute bedrest. You can take vigorous, healthy people in their physical prime and a week's bedrest will have dramatic effects on their muscle mass and level of physical functioning.

I've read that it's 10% after 10 days. Of course it depends on the person and amount of inactivity. Then it's another 10% every 10 days. That 10% is off the current top strength so it makes a smaller dent every time it decreases.

On the plus side, your muscles have amazing memory, so a guy who was benching 250 and stops for a year will get back up that level faster than a guy currently benching an all-time high of 185 who's been working out regularly. So if you have to take a break don't get discouraged just jump back in slow for a week and then crank it up.

If you go from intense use of the muscle to no use, then it will take..much longer then a week. Probably at least a month before you start to notice anything.

Weightlifters often take a week off every 2-4 months, and find that they're stronger when they come back from the rest.

I think a month is a good rule of thumb. You need a week or so every few months.

Yeah, I'd say 2-3 weeks.

I was sick for about.. 3-4 weeks very recently. Before that, I was going to the gym on a regular basis. When I stopped... and started again... damn were my muscles sore, as if it was the first time I had ever worked out all over again!

How long do you think that they take off every few months? Three or four days maybe?

Well, generally a full cycle of their routine..which would most likely be a week. If you figure they're lifting monday to friday then thats 5 days plus the 2 days they dont lift..

of course those on roids would be lifting 24/7/365 haha

My mother keeps quoting some study that claims sitting at a computer and slouching for as little as 1 hour per day causes irreversible muscle damage due to atrophy. I hear it constantly from her, but I don't know how true it is.