Hanging from a bar is having a moment. Some claim that it can decompress your spine and undo whatever the day did to it.
Hanging is a good exercise, but the claims you might have heard need some more nuance.
Yes, a dead hang decompresses your spine. Your body weight pulls spinal segments apart slightly, pressure inside the discs drops, and they take on a small amount of fluid during the process.
What a dead hang actually is
You grab a bar overhead, let your feet come off the floor, and hang there. Kinda like playing on monkey bars as a kid minus the swinging.
In a passive hang you let everything go slack, arms straight, shoulders relaxed and up near your ears. In an active hang you pull your shoulder blades down and slightly together so your shoulders sit away from your ears.
Passive hangs give you more stretch through your shoulders. Active asks more of the muscles of your back and rotator cuff. Active tends to be kinder to cranky shoulders.
Most of what people feel during a dead hang isn't happening in their spine at all. It's grip and it's shoulder. Holding your own body weight from two hands is hard work, and I suspect that's a decent chunk of why the people who stick with it feel better.
I went through a period of doing regular dead hangs myself. I won’t pretend that they’re life changing but they can help some people. I stopped doing them out of shoulder discomfort and a lack of perceived benefit. There are a few reasons why dead hangs might or might not be worth it. For starters, there’s no literature looking at dead hangs directly for back pain purposes. The closest analog is gravity inversion where the posture is reversed and people hang from their feet rather than gripping a bar with their hands. And while inversion or dead hangs do produce a real measurable difference in disc height from decompression, the difference is short lived and similar to something that we all do each day anyways.
Your spine already does this every night
Your spine loses height under load throughout the day and gains it back when you unload it during sleep. This effect can even be measured throughout the day with changes in activity. One study put 20 men through 30 minutes of walking [1]. They were split into two groups: lighter and heavier body weight. They had them walk and measured the changes in their height pre- and post-walking. The lighter group lost about 3.5 mm of height walking unloaded and 6.5 mm carrying a load. The heavier group lost 7-8.5 mm of height.
That's just ordinary daily physiology. You shrink across the day and you regain it lying in bed overnight.
As a biomechanist, I can tell you a hang is a faster, louder version of something your body already does for free every night. Which is fine. It just isn't a novel or unique mechanism that your body has been missing.
What the traction research actually found
Hanging itself has barely been studied, so the closest thing we have is vertical traction or inversion. A systematic review went looking for studies on the topic in people with nerve pain running into the leg and found only three [2]. The trials were different enough from each other that forming any sort of conclusion was not possible.
Added to bed rest, traction showed a benefit but the result was very low quality evidence. When it was added to physical therapy instead, the effect was so small it was statistically indistinguishable from nothing. Every effect they found was short-term.
It gets messier. Another review pulled together 37 traction studies and found the machines, forces, rhythms and session lengths were all over the place [3]. Only about 8% used the gravitational type that hanging is similar to. Another review found no difference between traction types at short-term follow-up, then floated the idea that whatever benefit shows up might not be mechanical at all [4].
The decompression is real. It just ends when your feet land back on the ground.
So is hanging worth it?
Two things come up constantly, so here they are straight.
The effect is strictly temporary. Your discs re-load as soon as you're standing again. That doesn't make it pointless, in the same way heat doesn't fix anything but does buy you a window where your pain feels better. A hang buys the same kind of window, and that relief is worth something.
Then there's the group that hangs for 30 seconds and gets shooting pain the second their feet touch down. If that's you, stop. An irritated nerve root doesn't always enjoy being pulled on. I still can't do a deep seated hamstring stretch without my sciatica reminding me about it, and I spent years doing them because I didn’t know any better.
So can dead hangs help a sore back? Maybe. And that maybe is also likely temporary. Okay I shouldn’t completely rag on the exercise. It’s healthy and useful to hang from a bar. It helps develop grip strength and temporarily decompresses your spine. That’s all good stuff. Just don’t expect it to change your life.
What to do this week
Give this a shot if you want to try hanging:
- Start with your feet on the floor. Bend your knees and offload maybe half your weight to whatever you’re hanging from. If you feel good, keep going.
- If the shoulder stretch feels intense, widen your grip. If your low back arches and complains, hold your feet slightly out in front of you.
- Have a goal to build toward about a minute of total hang time.
- Pair it with something that builds load tolerance, because the hang won't. At home: glute bridges and dead bugs, 2-3 sets of 8-10. At the gym: seated good mornings or back extensions, 2-3 sets of 8. Exercise has 249 trials behind it and a clinically meaningful effect on pain [5]. Hanging has three small ones and an unclear effect.
- If pain climbs above 4/10 while you're hanging, or you're noticeably worse the next morning, scale it back or stop, no problem.
Give it a few weeks and see how you feel. If nothing has changed, it's a grip and shoulder exercise you happen to enjoy, and that's a perfectly good reason to keep doing it. Just stop asking it to fix your disc.
As always, have a great weekend.
Best,
Mitch
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References
[1] Rodacki et al., 2005. Body mass as a factor in stature change. Clinical Biomechanics, 20(8), 799-805. doi:10.1016/j.clinbiomech.2005.04.005
[2] Vanti et al., 2021. Vertical traction for lumbar radiculopathy: a systematic review. Archives of Physiotherapy, 11(1), 7. doi:10.1186/s40945-021-00102-5
[3] Alrwaily et al., 2018. Assessment of variability in traction interventions for patients with low back pain: a systematic review. Chiropractic & Manual Therapies, 26, 35. doi:10.1186/s12998-018-0205-z
[4] Vanti et al., 2023. The effects of the addition of mechanical traction to physical therapy on low back pain? A systematic review with meta-analysis. Acta Orthopaedica et Traumatologica Turcica, 57(1), 3-16. doi:10.5152/j.aott.2023.21323
[5] Hayden et al., 2021. Exercise therapy for chronic low back pain. Cochrane Database of Systematic Reviews, 9(9), CD009790. doi:10.1002/14651858.CD009790.pub2
Disclaimer: this content is educational only and does not constitute medical advice. See a practitioner if you suspect serious spinal trauma from a fall or accident, or if you experience any of the following red flag symptoms: loss of bowel or bladder control, numbness in the groin or saddle area, rapidly worsening leg weakness, back pain with fever or feeling generally unwell, or unexplained weight loss with back pain.