The impact of falling when indoor bouldering (and how it destroys joints)

If you’ve missed this 40 second video on reddit, I think it’s still worth watching: Bouldering fall impact measured: is injury inevitable? #shorts - YouTube

I used an accelerometer to measure the impact of (indoor) bouldering falls. These falls can generate a lot of impact, almost as much as a car crash at 50 kmh or 30 mph. Not only that, the force goes up and down the spine, which is more dangerous according to Human Tolerance and Crash Survivability (Dennis Shanahan, 2004).

I started getting into this topic after a friend of mine fell and broke both of her arms. She was super strong and I really looked up to her… It was awful to see her in this state, she couldn’t even go to the toilet by herself :-/
Then recently, I went to an orthopedic surgeon because of some hip complications. He mentioned he is seeing more and more boulderers with irreversible joint issues. As a result, I decided to measure the impact of bouldering falls. I measured a couple of dozen falls in a few different ways. I tried the phyphox app on the phone first, but it only went up to 8g’s so I couldn’t get a good measurement. So I used a custom accelerometer that goes up to 16g’s.

I consistently got an impact of between 9g and 12g when jumping out of the bouldering wall and landing on the feet. Rolling would halve the impact. Of course, down climbing is effective too - but I recommend also rolling so that you learn it as a reflex in case of an accidental fall.

I’m convinced this means that jumping down will get you injured sooner or later. Sometimes due to an acute injury, but even if you don’t rupture or break something immediately, the accumulative effect of repeated high impacts will wear down your joints.

After I posted this video, I got a lot of feedback of people who had pain in their knees or back and couldn’t figure out why. Down climbing and rolling seemed to help a lot of them.

Now here’s my main point: most people who start out bouldering have no idea what they’re doing, so they end up copying other people. So if passionate climbers like you display good habits, like proper falling techniques, then newcomers will learn.
It can make a huge difference! I’m seeing the results in my local bouldering gym, more people are displaying proper falling techniques - and less people are getting injured.

If you have any ideas on how to make proper falling techniques the norm, let me know! :slight_smile:


Could you outline more specifics? Jumping from how far? Weight of the person? Type and density of foam?

Seems like there are tons of variables at play…

I absolutely don’t doubt that falls are hard on the body, btw.

I wonder if any studies have been done with the impacts in park skateboarding or bmx biking. How’s that for perspective? Hard pass on my part for those sports.

Not at all surprised by the forces involved. Nate has advocated for jugs connected to an autobelay at the top of bouldering walls, and I almost never try to land standing.

These types of rolling falls are only the first step. I suspect your friend who broke her arms wasn’t just dropping off the wall? Any day spent bouldering with a group makes it pretty clear that many people have avoided falling for a lot of their life. We can’t rewind life, so what to do?

The knee jerk answer (and where I’ve seen some folks immediately err) would be - spend time with the same sports in which kids learn to fall - but that comes with the same risk as learning it while climbing. In fact, I think nearly anything that involves unexpected falls will be pretty risky for adults who never learned it as children. For an adult who already has limited time to take up another sport just to learn to fall doesn’t make much sense.

In my opinion, gyms could get ahead of this a little by not building walls taller and taller, by putting cruxes lower to the ground more often than not, and by not allowing lazy setting that often includes some sideways jump at the top (seen all too often due to setters mimicking world cup boulders).

Shorter walls are obvious. Lower cruxes will allow adults to spend more time learning to spin off the wall without the risk of more time out of control in the air. That aerial awareness can absolutely be learned, and can’t be overvalued. But it takes lots of reps. Instead, gyms tend to have problems that let people get up the wall a bit so as not to be so discouraging.

@Bswitze I’d be surprised if the average fall in park or bmx is as hard as dropping off of a bouldering wall. Even when bailing from a trick (the equivalent of dropping off rather than a hard slamming fall), skaters and bmx can most often work with the momentum. They start learning that day 1. The big slams, that’s another story altogether.


@Kris yes to low cruxes and shorter walls (ahem the Front and BKB locations)

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@Bswitze I’m about 74kg, dropped from the top (about 4.5 high, so I think my legs were dangling about 2.5m above the floor). No idea what kind of density foam.

I did a search a while back and did find a study that measured the impact in gymnastics. This would vary from 5g to 16g if I remember correctly. 16g is insane. Can’t remember the exact situation, but I think it involved a flip and landing with almost straight legs (because that gets you points in gymnastics).

@Kris my friend broke her arms while doing an olympic style sideways dyno… So yeah, could’ve been bad setting. But she didn’t know how to fall at the time. I made a couple of video’s since then on how to fall properly and also started teaching it in a couple of bouldering gyms. But I noticed it wasn’t “cool”, and as a result not enough people were practising it. So since then I decided a cultural change would be more useful than giving lessons.

And I think you’re totally right about kids learning how to fall! There’s a judo teacher here that calculated we (as a society) could halve our spending on healthcare if people knew how to fall.

Earth’s gravity is constant 1g. Also, “g” is an acceleration, not a force. So the whole idea of measuring “gs” when falling is flawed. None of the apps you’re using will measure the force your body will incur when hitting the ground. That depends, among other things, on how quickly it happens: if you’re falling on a soft surface and roll, then the force of the fall is spread over time, thus having a smaller impact on your body.

I’m not trying to sound sassy here, I just prefer when people use physics the right way. Equating the fall from a boulder to a car accident should have people stop and think: "Is that real? "

But that’s exactly how acceleration (in this video expressed in g) works…

I missed this thread, but I’m super interested. Posting to follow!

I agree Amir. My point is that one shouldn’t use “gs” as a measure of force/impact, a phone is very unlikely to give a meaningful measurement, and equiparating a boulder fall to a car accident seems a bit… extreme :slight_smile:

Phone only went up to 8g so I used a custom accelerometer. In scientific studies they also use g’s. I’ve seen around 10g in judo throws (but those guys at least know how to break fall), 16g in gymnastics, and of course all kind of g’s in car accidents. For joints, (repetitive) peak force is pretty bad - according to my orthopedic surgeon (and some literature I found). So that’s another good reason to use g. Finally, by comparing it to car accidents, people will stop and think. You wouldn’t voluntarily get into a car accident 100 times a week, right? Somehow people expose themselves to similar peak forces when bouldering and don’t realise the damage it can do long term. I got a LOT of messages of people who had pain in their knees or back, couldn’t get rid of it with physiotherapy, and then got rid of it when they stopped jumping out of the bouldering wall.

I’m all ears if you have any suggestions, but right now the assumptions you’re making do not reflect the level of effort I put into this.

Really glad you posted this @AmirNickname ! Umm I’ll be unequivocal in this: fuck tall indoor bouldering walls. I’m 32 years old and don’t have time to drop 15ft onto my ankles. I like walls to be 10-12ft high and overhanging. Preferably can be topped out as well! Slabs with protruding stuff for me to hit on the way down? Not about it. I’ve never measured actual force in this setting but I do try to avoid falling from 15ft in any other setting in my life and have seen too many people get injured falling straight down bouldering indoors. So…I just spare my body the pain and let my ego take the hit of not doing tall indoor boulders. Not worth it for me personally.

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By the way, see that square box in front of me in the video? That collects a lot more data than just acceleration. I’ve collected some data of a beginner, an intermediate (myself) and a pro climber. We’ve done the same moonboard problem for instance. When the shiny server is up and running, maybe you’d like to take a look? I’d be interested to know if such data (in the long run) could be more informative than just video analysis.

Good falling technique is crucial for bouldering longevity, in my view - especially in this era of taller gym bouldering walls and seamless flooring allowing for better fall tactics.

When the first bouldering-only gym in my hometown opened (when I was on the youth team at the sister gym across town), it was one of the first wave of gyms with tall walls and seamless flooring. Futurist installed the flooring, and our coach mandated that the whole team attend a falling clinic hosted by Futurist’s founder Timy Fairfield, where he emphasized proper falling technique in a bunch of different scenarios. I thought it was really unnecessary at the time, but it drilled into me those habits early(ish, I was 16 or 17 or 18 at the time) and now rolling out is incredibly automatic to me in virtually all falling contexts, as well as slapping the ground to break back-first falls and other good falling form.

I frequently get comments like “nice dismount” or things like that because my rollouts are fairly aggressive but I’d rather get eye-rolly comments than injured falling, especially in gym.


I’d love to see a video

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@lorenzo Acceleration g’s are used all over in physics. In the case of falling, the acceleration value is just negative, ie a deceleration. So the faster you stop, the higher the g load. To understand the force in terms of weight multiply the g force by the mass of the object. So a 150 lb mass decelerating at 10g would experience, if only for a moment, 1500 lb force. Does that help you understand how g’s are used in physics?

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Thanks for the explanation @pawilkes :slight_smile:

I wouldn’t be surprised if the actual impact isn’t much higher. I wear a MOOV Now when running, and it reports an impact score expressed in g’s and I get an impact score of 8-12gs while jogging.

Could you be my hero and take a few falls from a bouldering wall with your MOOV Now? I’d be VERY interested to see the comparison to you jogging!

Also, I must say that impact alone really doesn’t tell the whole story. When running, you’re doing something your body is designed to do, with shoes that are also designed for that purpose. So hopefully, it’s something you can do for many years while staying healthy.

I don’t think that’d work. It measures averages over the running session. Maybe if I start a running session at the top of the wall, drop, and then stop it, but I doubt the algorithm it runs will gel with that. I’ll see if I remember to do it tomorrow!

Have you checked out the Beast Sensor at all? I think they’ve emphasised the weight room but you might want to reach out to them and ask if they’d be interested in teaming up to do some data-driven analysis of climbing.

Ah yeah that could be tricky, I hope you can get it to work!

And thanks for the tip about beast sensor, I hadn’t heard about them before!