I was perusing a bunch of sports medicine stuff the other day, and I finally remembered to dig up the normal range of motion for the major joints.

"Hip flexion: Flex knee and bring thigh close to abdomen," it says. "110-130 degrees." Well, given a few minutes to stretch, I can get my knee hooked around the back of my shoulder, which degree-wise is something in excess of a hundred and eighty.

"Internal hip rotation: Flex knee and swing away from midline. 40 degrees." Sitting upright, I can press the top of one thigh to the floor, bend my knee all the way, and hook the arch of my foot over my bicep so that I can get a direct look at whatever part of my foot I've blistered this time. My toes rest just short of my shoulder. Fairly comfortable, actually.

"Shoulder vertical extension: Raise arm straight backwards. 60 degrees. Shoulder horizontal extension: Swing arms horizontally backwards. 45 degrees." I crack my back by pushing both arms around horizontally backwards, lacing my fingers together, and swinging them like I'm aiming to get them over my head from behind. I hit 90 degrees -- straight out behind me -- or thereabouts. It's good for popping the upper thoracic vertebrae.

"Lumbar spine extension: Bend backwards from standing position. 30 degrees." I can do this pretty easily. (On floor, I hasten to add. Although that's one of the more comfortable brace positions to stand in, so I don't imagine I'd have a lot of trouble doing a layback Ina Bauer on skates, either.) The main reason I don't roll backwards into a standing backbend anymore is that I don't quite trust my abs.

"Elbow supination: Turn lower arm so that palm of hand faces up. 90 degrees." Sure, I can do that. I can also keep rotating inwards until I can almost get my palm straight up again after a full revolution. I do it fairly often, as it reliably makes my right elbow pop.

I don't think this test is calibrated for me.

Joint hypermobility, known colloquially as being double-jointed, seems to be mostly hereditary. I know it is in my case; my mother is similarly flexible. I also inherited the tendency to sound like a giant bowl of Rice Krispies when I stretch, which sometimes alarms others. The crunchy noises are a mix of cavitation (fingers, toes, neck, back), which cannot be repeated immediately, and ligaments snapping over something else (elbow, ankle, wrists), which happen every time I move that way. Some are a mix of both -- I can cavitation-pop both patellae if I twist them or kneel just right, but the underlying joint ligament-crackles whenever I rise from a squat. If knuckle-popping drives you crazy, I am a bad person to hang around.

Hypermobility syndromes can be rather terrible. They sometimes result from connective tissue disorders like Marfan's or Ehlers-Danlos syndrome, and if they're severe enough, they can progress from dislocating things during activities as normal as getting your socks and shoes on in the morning while young, to osteoarthritis when older. I'm not nearly so bad -- I have to stretch a lot, but so far as I know I've never dislocated anything. None of the horrifying Rice Krispie noises come with pain, and the general medical response is 'if the popping doesn't hurt, don't worry about it'. (Cracking your knuckles doesn't cause arthritis. That's an old wives' tale. Dude actually won an IgNobel with a counter-demonstration.)

Interestingly, while I was digging around the PubMeds for stuff on this, I turned up a few studies suggesting a strong correlation between hypermobility syndromes and panic disorder. They correctly do not conclude it is a causative relationship in either direction, although at least one study has astutely limited their sample population to people with actual panic disorder, i.e., not anxiety caused by another known medical condition like adrenal tumor or PTSD. The research seems mostly rather new; I see one paper in The Lancet in 1988, and one citation in another paper that comes from 1998, but other than that it all seems to have happened in the last ten years. I can't actually read any of these damn things myself, of course, because they're all behind paywalls, but if I'm really bored one day I might go down to Tufts or MIT and see if I can dig up the print versions and make some copies.

It seems obvious to me, given the overwhelming female prevalence of both panic disorder and hypermobility syndromes, that someone should go check on hormones. Flexibility waxes and wanes measurably according to menstrual cycle for most women, as well as when preparing to give birth, and panic disorder is often noted to be worse, sometimes catastrophically so, during the pre-menstrual week. Panic disorder is often filed with and treated the same way as PTSD, which so far seems to be a result of some kind of trauma fucking up the stress hormone release system on the hypothamamus-pituitary axis. My personal experience is that panic attacks are not really what you'd think of as psychological in nature, and no more consciously controllable than the cramps or crying jags of PMS -- I can ignore it or I can treat it symptomatically, but I cannot actually will it to go the fuck away.

[ETA: Was reminded again that I now carry a camera around everywhere I go. This is what I mean about being bendy. That was shot in the studio mirror, so I've actually got my left elbow dragged up behind my head to grab my right foot, which is leaning on my arm just short of my right shoulder. I admit to having some difficulty aiming the camera, but I'm terrible at that even when I'm standing normally on my own two feet.

The position is not particularly uncomfortable, and I held it for, I don't know, a minute or so? while playing with the zoom and trying to get a photo that wasn't blurry. It's fairly normal for me. In many cases, I'm limited by the fact that I am solid and cannot put parts of me through other parts of me. Some bends are difficult not because of the stretch, but because of positional asphyxiation. I can lay on my back and swing my feet straight up over my head, until my knees are resting comfortably alongside my ears, but my chin gets jammed into my chest and it's hard to breathe.

I've been meaning to check on all this for quite a while. I've always known I was probably more flexible than most people, but when the circus acrobat did a double-take, I thought perhaps it was time to investigate further.]

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