Why do the backs of my legs tingle when I'm afraid?

January 30, 2012 2:21 PM

Why do the backs of my legs tingle when I'm scared?

I've noticed that when I am either at great heights, or looking at a picture of great heights, I get a furious tingling/contraction in my hamstrings and the backs of my hips. Why? What possible connection is there between fear and the backs of my legs? It's not sometimes, it's every time.

posted by facetious to Health & Fitness (9 answers total)

I get tingly and covered in goose bumps when I'm stimulated in various ways (tickled, frightened, anxious, excited, even confused.) And some people get actual muscle weakness from emotional stimuli (as I found out when being assessed for possible narcolepsy just last week!) Your brain is part of your nervous system, and nerves are everywhere. See, also, fight-or-flight.
posted by SMPA at 2:30 PM on January 30, 2012

I'm wondering if it's hamstrings because you do/don't want to jump. You'd tense them to prepare.
posted by lokta at 2:34 PM on January 30, 2012 [1 favorite]

I get this in the backs of my knees when I see/hear about people getting injured... hadn't considered it as a fight or flight response until just now.
posted by lizifer at 3:27 PM on January 30, 2012

Best answer: I also get a tingling in the backs of my legs whenever I think about people getting injured, especially when it has to do with falling from heights or some other injury to the legs.

I'm no neuroscientist (but I have studied neuroscience on an undergrad level). If I had to make a guess I'd say it's to do with your mirror neurons which are part of empathy - they're located in the motor part of the brain & when you see someone doing something, you imagine yourself doing it & imagine how you would feel doing it. The other half has to do with the sciatic nerve that has to do with sensation & motor control in your legs.

You're basically imagining it happening to you & sending a signal to your legs to prep for something like that, which in turn causes the tingling sensation you'd feel if something like that happened to you. A sort of feedback loop caused my largely imaginary stimuli.

FWIW I hate that feeling, especially in winter when it's cold & your jeans are rubbing against your leg hairs as you walk & you didn't notice until that moment.
posted by MesoFilter at 5:06 PM on January 30, 2012 [2 favorites]

Years ago, I saw a blind guy walk to the edge of an office building loading dock and almost fall into a trash compactor. When I got him back into the lobby of the building, he described a similar sensation that stopped him before the last step. Subconscious sonar?
posted by Mr. Yuck at 5:33 PM on January 30, 2012 [1 favorite]

Data point that may interest you: This used to happen to me when my sister would make me look at her appendix scar. When I got my own considerably nastier-looking appendix scar, it stopped.
posted by gnomeloaf at 7:32 PM on January 30, 2012

I get the furious tingling in my butt when I'm near heights. I refer to them as "ass tingles" and they only happen with heights-related things. My friends all think it's hilarious and until today I thought I was alone.
posted by simplethings at 10:05 PM on January 30, 2012

Ass tingles! Yes, me too! I first noticed it in the fourth grade when the teacher said 'hand in your homework' and I realized that I'd forgotten to do it the night before. It happens now in any kind of sudden-anxiety moment. Glad I'm not the only one.
posted by oceanmorning at 12:14 AM on January 31, 2012

I would guess its part of a fight-or-flight response. Your legs are getting ready to run like they never have before.
posted by General Tonic at 9:03 AM on January 31, 2012