# Why must I bounce my leg? **URL:** \ **Category:** Factual Questions\ **Created:** [April 27, 2002, 4:14pm UTC](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966 "2002-04-27T16:14:23Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![GopherGod72](https://avatars.discourse-cdn.com/v4/letter/g/f0a364/32.png) [@GopherGod72](https://boards.straightdope.com/u/GopherGod72)\ **Post date:** [April 27, 2002, 4:14pm UTC](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966/1 "2002-04-27T16:14:23Z")
I’ve noticed a lot of people do this. It seems to be mostly guys. I just cant seem to keep my legs (particularly the right one) still. Like right now i’m sitting at work and have the ball of my right foot on the ground and my heel and leg bouncing up and down at a rate of probably 3 or 4 bounces a second. Funny thing is, I am totaly relaxed. During concentration or stress it really gets moving. I do this pretty much all day. Even at night while lying in bed I’ll be bouncing my foot in a similar mannor and have to conciously make myself stop. It doesn’t bother me at all, in fact it seems relaxing. It does, however, bother my SO as she doesn’t seem to care for the automatic vibrating couch effect during movies. BTW I’m nearly 30 and this seems to be something i’ve picked up within the last year or two. Anybody else experience this or know why it happens?? ---
**Author:** ![ski](https://avatars.discourse-cdn.com/v4/letter/s/bbe5ce/32.png) [@ski](https://boards.straightdope.com/u/ski)\ **Post date:** [April 27, 2002, 4:48pm UTC](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966/2 "2002-04-27T16:48:13Z")
I’ve been doing this for years. I don’t know why. I did see a study somewhere (no cite) that people who fidget like this can burn up to about 700 extra calories a DAY! (I found this hard to believe too, but it came from a reputable source as I recall.) So bounce your legs to fitness, I suppose. ---
**Author:** ![papergirl](https://avatars.discourse-cdn.com/v4/letter/p/aca169/32.png) [@papergirl](https://boards.straightdope.com/u/papergirl)\ **Post date:** [April 27, 2002, 5:23pm UTC](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966/3 "2002-04-27T17:23:10Z")
Woman here: I do this too! Right leg, almost constantly. My theory is that it’s a sort of physical white noise: for me, at least, it seems to help keep my back from getting achy when I sit, and somehow blocks out some of the outside stimuli so I can concentrate when I’m proofreading or concentrating. I’ve taught myself to not do it in bed–took me years to switch to wagging my foot instead of bouncing it. You are not alone. 😃 k ---
**Author:** ![lolagranola](https://avatars.discourse-cdn.com/v4/letter/l/ea5d25/32.png) [@lolagranola](https://boards.straightdope.com/u/lolagranola)\ **Post date:** [April 27, 2002, 5:42pm UTC](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966/4 "2002-04-27T17:42:42Z")
I don’t know why, but I constantly fidget as well. Mostly lower body. Strangely, I’m 30 and this fidgeting seems to have picked up the pace recently as well. ---
**Author:** ![femtosecond](https://avatars.discourse-cdn.com/v4/letter/f/f08c70/32.png) [@femtosecond](https://boards.straightdope.com/u/femtosecond)\ **Post date:** [April 27, 2002, 6:26pm UTC](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966/5 "2002-04-27T18:26:15Z")
[Straight Dope Staff Report: Why do your legs tremble uncontrollably sometimes when rock climbing?](http://www.straightdope.com/mailbag/mclimb.html) > [@](#): > > Particularly during rock climbing, the calf muscle is under constant demand to perform in carrying someone’s weight. During normal ambulation, there is a rest/contraction cycle during which the muscle contracts to propel the person forward. This is done alternately by both legs, giving a moment of rest and relaxation to the opposite leg. These phases are called push-off and swing-thru. The push-off phase causes the muscle to contract, the swing-thru phase causes the muscle to relax. When alternation of contraction and relaxation are not possible, the muscle fatigues quickly and responds with a cramp-like action, causing the foot to go up and down rapidly. Pushing the heel down breaks up the spastic contraction and lengthens the muscle so it can contract (shorten) again later in the cycle. Your calf muscle isn’t built for static strain. It’s not rock climbing, but sitting ball down heel up is static enough to make it fatigue and try to do a movement pattern it likes better. ---
**Author:** ![femtosecond](https://avatars.discourse-cdn.com/v4/letter/f/f08c70/32.png) [@femtosecond](https://boards.straightdope.com/u/femtosecond)\ **Post date:** [April 27, 2002, 6:44pm UTC](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966/6 "2002-04-27T18:44:33Z")
Of course being the fidgety type you don’t need a reason once you got used to the movement. Googling for “fidget+calories” does the trick: [http://www.inq7.net/lif/2002/mar/05/lif\_3-2.htm](http://www.inq7.net/lif/2002/mar/05/lif_3-2.htm) ---
**Author:** ![TheNerd](https://avatars.discourse-cdn.com/v4/letter/t/858c86/32.png) [@TheNerd](https://boards.straightdope.com/u/TheNerd)\ **Post date:** [April 27, 2002, 6:49pm UTC](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966/7 "2002-04-27T18:49:17Z")
Has anyone else noticed that not only is this fidgiting behaviour fairly automatic, it also seems to be autonomous. By that I mean that I can set both of my legs to bouncing, and they go at slightly different rates (left is a bit slower). I sure as hell couldn’t do that if I had to think about it. ---
**Author:** ![Kat](https://avatars.discourse-cdn.com/v4/letter/k/b19c9b/32.png) [@Kat](https://boards.straightdope.com/u/Kat)\ **Post date:** [April 27, 2002, 10:37pm UTC](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966/8 "2002-04-27T22:37:49Z")
I do this, too, and my mother tells me that it’s something that her father did. It can happen unconsciously or I can start it up consciously (I just did to experiment with **TheNerd** ’s theory and yes, both legs fidget at different rates.) I can also stop the bouncing with no effort. ---
**Author:** ![cleops](https://avatars.discourse-cdn.com/v4/letter/c/2acd7d/32.png) [@cleops](https://boards.straightdope.com/u/cleops)\ **Post date:** [April 27, 2002, 10:54pm UTC](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966/9 "2002-04-27T22:54:06Z")
Yes, I’ve noticed it in others. STOP IT! 😛 ---
**Author:** ![Mr.Duality](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mr.duality/32/4098_2.png) [@Mr.Duality](https://boards.straightdope.com/u/Mr.Duality)\ **Post date:** [April 27, 2002, 11:24pm UTC](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966/10 "2002-04-27T23:24:20Z")
The “sewing machine leg” syndrome alluded to by femtosecond is not the same thing as the leg bouncing described in the OP. I know because I’ve done both. I believe sewing machine leg results from near-exhaustion of leg muscles. I read somewhere many moons ago that bouncing knee is a symptom of neurosis. ---
**Author:** ![Why\_A\_Duck](https://avatars.discourse-cdn.com/v4/letter/w/13edae/32.png) [@Why\_A\_Duck](https://boards.straightdope.com/u/Why_A_Duck)\ **Post date:** [April 27, 2002, 11:25pm UTC](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966/11 "2002-04-27T23:25:34Z")
Yeah stop it. My wife is always blaming me for it. 😉 ---
**Author:** ![billy](https://avatars.discourse-cdn.com/v4/letter/b/ecd19e/32.png) [@billy](https://boards.straightdope.com/u/billy)\ **Post date:** [April 27, 2002, 11:31pm UTC](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966/12 "2002-04-27T23:31:28Z")
My wife told me years ago that when I’m resting, with eyes closed, she could only tell if I was awake by looking at my foot, which moves so much it even bothers me. ---
**Author:** ![Mr.Duality](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mr.duality/32/4098_2.png) [@Mr.Duality](https://boards.straightdope.com/u/Mr.Duality)\ **Post date:** [April 27, 2002, 11:32pm UTC](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966/13 "2002-04-27T23:32:41Z")
BTW, ‘sewing machine leg’ takes place at a much higher frequency than ‘bouncing knee’, in my experience. In other words, ‘bouncing knee’ is slower than ‘sewing machine leg’. ---
**Author:** ![murphydog](https://avatars.discourse-cdn.com/v4/letter/m/b487fb/32.png) [@murphydog](https://boards.straightdope.com/u/murphydog)\ **Post date:** [April 27, 2002, 11:39pm UTC](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966/14 "2002-04-27T23:39:02Z")
I remember seeing a documentary on TV about body language. According to the expert on body language, when people do this with thier leg(s) while sitting they are subcontiously saying: _“I do not want to be here”._ ---
**Author:** ![bernse](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@bernse](https://boards.straightdope.com/u/bernse)\ **Post date:** [April 28, 2002, 1:00am UTC](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966/15 "2002-04-28T01:00:09Z")
Our family calls it “twitching”. Every male in our family does and every male on my mothers side. ---
**Author:** ![bytheway](https://avatars.discourse-cdn.com/v4/letter/b/df705f/32.png) [@bytheway](https://boards.straightdope.com/u/bytheway)\ **Post date:** [April 28, 2002, 1:54am UTC](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966/16 "2002-04-28T01:54:52Z")
I do it too. I don’t know why, but I have done it for as long as I can remember. I also have a tendency to fidget with my legs while standing. It sure would be nice if it was a good way to burn calories… ---
**Author:** ![evilhanz](https://avatars.discourse-cdn.com/v4/letter/e/ba8739/32.png) [@evilhanz](https://boards.straightdope.com/u/evilhanz)\ **Post date:** [April 28, 2002, 3:00am UTC](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966/17 "2002-04-28T03:00:38Z")
I think murphydog might have seen one of those Desmond Morris documentaries. I remember reading one of his books where he describes this as a “Displacement Activity”, a small meaningless physical manifestation of some sort of personal or social uncertainty. Whatever social situation you find yourself in, or even when you’re alone, if there are conflicting urges, you’ll resort to one of these displacement activities - a boucing leg, twirling your hair, snacking, ringing your hands, etc. to divert the energy caused by that inner turmoil. Most people pick one displacement activity for any conflict. This is not authoritative. It’s just one possible explanantion. ---
**Author:** ![levdrakon](https://avatars.discourse-cdn.com/v4/letter/l/49beb7/32.png) [@levdrakon](https://boards.straightdope.com/u/levdrakon)\ **Post date:** [April 28, 2002, 12:13pm UTC](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966/18 "2002-04-28T12:13:44Z")
My mother had sewing machine leg syndrome too. It was kinda fun when I was sitting on her knee. She did it when she was concentrating on a task or thinking about something. She also clucked her tongue from side to side at about the same rate. I haven’t noticed my siblings doing it, but I have sewing machine leg syndrome too. Not sure when it started, but probably my teens or twenties. I find it very relaxing when I’m otherwise sitting still. Right leg mostly, but left sometimes too. Never at the same time from what I can recall though, but one leg will take off after the first one quits. I’ve caught myself clucking my tongue as well, but not as often as mom. I also have restless leg syndrome which at times can keep me up for awhile at night. I wonder if the two are related? ---
**Author:** ![Hazel](https://avatars.discourse-cdn.com/v4/letter/h/e56c9b/32.png) [@Hazel](https://boards.straightdope.com/u/Hazel)\ **Post date:** [April 28, 2002, 12:28pm UTC](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966/19 "2002-04-28T12:28:52Z")
I don’t do this myself. It seems to me to be mainly males who do this, esp. males in the age range of teens through thirties. I’ve always vaguely suspected testosterone was a factor; that maybe this action was an indication that the person was overdue for some sexual activity? ---
**Author:** ![ageless6](https://avatars.discourse-cdn.com/v4/letter/a/9de053/32.png) [@ageless6](https://boards.straightdope.com/u/ageless6)\ **Post date:** [April 28, 2002, 12:43pm UTC](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966/20 "2002-04-28T12:43:31Z")
Hazel: I’m male and I can’t do it. Would you like to get together and practice bouncing our legs? [Next page](https://boards.straightdope.com/t/why-must-i-bounce-my-leg/105966.md?page=2)