Well, will it?
I do about 35 minutes a night–10 minutes of cardio warmup, 15 minutes free weights, and 10 minutes of squats/lunges/hamstring curls. I prefer doing it barefoot because I find it more comfortable, but my sister had a fit when I mentioned this and said I was ruining my knees. I’m skeptical. I don’t feel any knee strain during my workouts and haven’t had any discomfort since I began this routine (It’s been a few months now). So what’s the scoop?
Nah, there shouldn’t be any problems.
Thanks, ultrafilter. It’s always gratifying to have one more item to add to your list of “ha, ha, I was right and you were wrong” moments with which to torment your well-meaning but know-it-all sister.
Ask you sister why not wearing shoes for half an hour a night will ruin your knees… the response should be entertaining (or non-existant) 
. We don’t need shoes to keep our knees intact while doing squats any more than we need to wear gloves while doing push-ups to keep our elbows healthy. Don’t make any sense at all.
IANAD, but I am a martial artist with bad knees. I think that there may be a grain of truth to the argument if you were donig something high-impact, such as running or anything involving much jumping. True/untrue?
Running on a track/pavement, yes. On a nice, padded floor, no. It also depends on if you run/walk properly, or smack your feet on the ground.
I guess I smack my feet into the ground, because I took up running about 3 weeks ago, and have aged my knees about 60 years in that time. I was wearing shoes and everything. I am now looking for a low-impact substitute for running, that won’t cost me $40/mo for a gym membership 
Have you tried biking? I’m assuming that and, say, rollerblading are both softer on the knees.
I’m not much of a swimmer, but I hear it’s great aerobic exercise, and low impact. I don’t know about the cost – in some places there are free public pools (funded by taxes), right? Also it requires no equipment more expensive than a bathing suit.
Everyone I know whose not a runner (that is, makes it thier primary sport) ducks out rather quickly because they ruin their knees (many are ex-military, so they did a lot of it and probably under less-than-ideal conditions). I always avoided running for that very reason.
I can’t recall the exact statistics, but I recall that jumproping provides cardiovascular/calorie-burning benefits that are on par with running. Swimming also.
One thing I’ve been meaning to get into is running along the beach. I figure this will be good because 1) it’s lower-impact than running on pavement 2) will stregnthen stabilizer muscles/ankles because of slippage. That may be worth looking into. Of course, you/I might also twist an ankle the first time out…
Biking is not an option due to cheapskateness (have you seen the price of bikes lately?). I’ve always hated swimming, but it doesn’t matter anyway because the only pools around here charge an arm and a leg. I’m trying to improve my running technique so I don’t hurt myself so bad.
I got a decent bike at K-mart for 50 dollars two or three years ago(comparable to a good pair of running shoes). It still works just fine. You don’t have to spend 200 dollars on a bike you know…
I must be lucky because I am one of those that has a bad knee that got better when I started running and lifting weights. Of course I don’t run 5 miles a day every day, but I believe in moderation for health and fitness. 
(2-3 miles three times a week)
Depending on where you are, there are “running clubs” that sponsor seminars on how to be a better runner. Think about jumproping, all you need is $10 and some 10’ ceilings (or just go outside). Depending on what you’re trying to accomplish (i.e. not getting good at running, but just the cardio workout), give the good old Bear Crawl a try. Yeah, you look like an idiot, but it’ll knock you on your ass pretty quickly.
Some martial arts techniques put unnecessary strain on your knees. If you don’t get some of the mechanics of the movements juuuuust right (such as when you are fatigued near the end of your workout), you can put more stress on your knees than the movements ever intended to (this I’m sure you know as would anyone who has ever accidentally boggled a kick - damn, that can hurt! :eek: )
Otherwise, after almost 6 years of martial arts (then a four year interruption) I’m back at it. Knees are fine. And I jump around like a bouncing rubber Ninja Turtle. I used to do 2.5 hours of martial arts 6 days a week, including 15 minutes of running/jumping jacks for cardio – all barefoot – now ten years later, no ill effects on my knees.
Nowadays I wear martial arts shoes, but because i’m training in a gym where I do NOT want to catch some foot nasty! No barefeet at this place (yuck!) But my martial arts shoes are essentially the same as being barefoot as far as “support” goes (it’s like of like wearing leather socks). In addition a long martial arts workout, I do weights, stationary bike, weirdo stairmaster doo-hick, etc. in my martial arts shoes. For running though I do switch to proper running shoes. Though that has more to with foot comfort.
NOTE: It’s likely a very inidividual thing. My knees and your knees might not be built quite the same as your knees. A colleague in the same martial arts class had to wear knee braces for everything. People are built differently, have different walking gaits. Some folks are just born with tough knees, others are born with not-so-tough knees.
The only big caution about barefoot is with the free weights. Open-toed shoes/barefoot + free weights can lead to really hurt tootsies. A typical running shoe doesn’t offer that much protection, but if you or someone else drops a weight, that little wee bit protection is better than nothing.
For this reason and the aforementioned “picking up a foot nasty” I wear some kind of shoes in a public gym at all times. If you’re at home, you’re not feeling any fatigue or strain in your knees, I don’t see a problem.
Doper Discalimer: I do NOT have any background in kineisiology or sports med.
Yeah, but only when we’re talking about light weights. If you drop a 15 lb. dumbbell, sure, the shoes’ll make a difference. If you drop an 80 lb. dumbbell, it’s a different story.
Thanks for the suggestions, everybody.
Very true. I was thinking more of the little ones. When I was about nine, my friend’s little brother was horsing around with some 5 or 10 lb thing and dropped it on his bare toe. Tore the nail off. Grossed me out - thoroughly!