Saturday, February 23, 2013

Backpacks and squats

I spotted an interesting report yesterday about the potential dangers of carrying a heavy backpack in terms of nerve damage at the shoulders.

...the pressure of heavy loads carried on the back have the potential to damage the soft tissues of the shoulder, causing microstructural damage to the nerves. 
The result could be anything from simple irritation to diminished nerve capacity, ultimately limiting the muscles' ability to respond to the brain's signals, inhibiting movement of the hand and the dexterity of the fingers. In practice, this could impact functionality, reducing a worker's ability to operate machinery, compromise a soldiers' shooting response time, or limiting a child's writing or drawing capacity.
The context of the study was soldiers carrying heavy backpacks (I am trying to find the actual study - might be this)

However, it did make me think of the potential damage that could be caused by heavy back squats where you have large weights right on this sensitive area.  It also made me think about what Bill DeSimone explained about the squat:


MRT said...

I think you have to differentiate between a long-lasting pressure like from a heavy backpack and the short bouts of a barbell as well as the differences in posture and muscle activation. (Patients get pressure ulceras too, but only from long-lasting low pressure, for seconds your body can tolerate a lot of pressure without harm)
Although a few big squatters have injured their axillary nerve (1200lbs squat) this still was often a problem of mobility/activation (combined with pushing the limits of the human body under heavy steroids).
The possibility of nerve damage because of squats is almost zero, still as always some individuals can aggravate/get problems like Thoracic outlet or even damages.
Bill DeSimone in my opinion has a deeply flawed logic and you can immediately see that he has no scientific/medical/practical background, wouldn't agree with almost any of his stuff.

Stuart Gilbert said... to disagree with you wholeheartedly here. Bill's concerns about the squat mainly revolve around the potential for poorly performed reps with a heavy bar at the top of your spine to negatively affect one or more of the many joint facets and musculature attachments of the spine. Over time poor posture on reps with load can cause negative effects, which may lead to your back being thrown out, even during an unrelated event,such as putting on your socks, but by then the damage has already been done.And who can honestly say, during their weight training career that they have performed EVERY rep 100% correctly? Without hopefully being sexist, women with large chests often succumb to back pain over the years due to the "weight" out front, coupled with poor posture during daily movements. The weight can be smaller, and the negative effects happen with constant misuse over time, such as the back pack, or occur with heavier loads in a more acute fashion, such as poorly performed reps in the back squat.
As Bill says anyway, he is not attempting to convince people not to squat. He merely offers a lower risk alternative view point for those of us who are more safety minded and wish to play the percentages. If you are emotionally tied to an exercise then SQUAT ON brother....but you may wish to revise your approach if anything does happen in the future, but I wouldn't wish that on anyone.

Anonymous said...

I'm not qualified to comment on the science behind Mr. Desimone's choices but I do know my body and what feels right and wrong when using it. I've spent my 30+ years working heavy manual labor and never once suffered an injury on the job. Any injury that I've suffered has been in the weight room performing exercises with supposedly correct form. I listened to the experts instead of my body and suffered because of it. After some experimentation with alternative exercises and listening to the feedback my body was giving me, the exercises that I use are the ones that Mr. Desimone advocates. While there are many people who can perform other lifts safely, I am not one of them and I imagine that there are many others just like me. Common sense alone raises the question of safety about exercises that people need to spend a great deal of time and effort convincing others of their safety. There is a reason that so many people suffer injuries with exercises like the squat and instead of admitting that their relatively unsafe, we blame the people who are injured. That seems foolish to me. If it feels wrong, don't do it; that's been the most important lesson that I've learned while weightlifting. There are numerous alternatives so there is absolutely no reason to stubbornly adhere to a single exercise if it's clear that that exercise may cause you harm.

To quote the legendary Bruce Lee, "Take what is useful and discard the rest."

Stuart Gilbert said...

Couldn't have said it better myself....

Anonymous said...

Right on! how many times in manual labor do you lift the equivalent of your body weight on to your upper spine? It's not practical and it's dangerous.

MTR said...

Regarding the back pack topic (which was the focus of the post) you state the same as I do, saying that chronic overload (u mentioned large breasted women) can cause NERVE DAMAGE; these inuries occur, as I was trying to show, with constant pressure (like skin ulcers); the other kind of nerve inury is a distraction or very acute compression. That is why i differentiated and said that nerve damage during squats (which was the hypothesis of the blog post) like in the study mentioned are highly unlikely due to different load and activation characteristics, different posture and the anatomy of the shoulder girdle (except the mentioned rare injuries of the axillary nerve during very heavy squats, often unter the use of performance enhancing drugs)

THe injuries you talk about are degenerative (u describe discogenic injury by saying "blow out") - totally different etiology !!

Regarding Mr.Desimone, i disagree with his opinion (because going throug it phrase by phrase we just focus on the mentioned squat - leg press argument) because:
1. The leg press is often times not as safe as everyone claims, most trainees cant control their lumbopelvic region, have poor leg axis control, no idea of biomechanics and usually train alone with stupid high loads on the leg press. I know of enough acute and chronic injuries.
2. The use of the leg press applies only to senseless, isolated muscle building (like using an electronic muscle stimulator) because you don't integrate the movement of the legs with hips/core, you don't train the important patterns of hip hinging, and thoracopelvic control

You can go on with such differences for a while.
Point is: The leg press has almost no carryover to athletic abilities and/or daily activities because you cannot use your "strength" as your hips/core are not accustomed to stabilizing any load, neither is your coordination or movement pattern trained to do so.
The aim of training is to place a DEMAND on the body, therefore the beauty of the squat is that you have to stabilize the load with your spinal musculature which is designed to do so in a perfect way.
And you should train movement patterns that have a sense in your sport / life.
As far as spine biomechanics i would rahter refer to Stuart McGill who shows his knowledge with his results, research, clinical application and has the expected degrees on top.

Anyone intersted in real strength has therefore not a lot of use for the leg press instead of secondary hypertrophy.

The word of "safety" again is mostly used by people with lesser experience, because no exercise has differnences of safety (except maybe bosu ball stuff which can be simply unsafe) because any exercise can harm you as well as train you. Your execution matters and anyone can learn to squat/dedalift etc. in a way where no overload/injury will be done.
But exercises pose different demands of coordination and teaching of individuals that know these exercises, not reading mens health and squat (which is why people get hurt)
Interestingly, we squat above 500-600 pounds regularly and people squatting 100 pounds ask how to fix their knee pain - showing not the squat hurt them but their execution.
Still certain populations without athletic regards can benefit from the leg press and dont need to squat but this statement is different than the leg press is "safer" or "better", isnt it?

Chris said...


Bill is not to totally against squats he recommends belt squats for example. It is the loading of the spine that he questions.

You point about carry over to athletic ability is a bit dodgy. Skills are specific. Getting stronger in the legs/hips whether by leg press or squat is what is important. Then you apply that strength to the specific skill

None of this of course means that we shouldn't maintain the ability to squat - it is a vital natural movement pattern. it is the loaded back squat that is questioned.

Have you read Lyle McDonald's squats vs leg press piece?

"The leg press, properly performed (meaning keeping your ego in check, taking the sled to parallel or slightly below) in a progressive fashion is an excellent way to train the lower body while avoiding some issues that can make squatting problematic for some trainees."

MTR said...

I would agree with Lyle McDonald in your cited part - and with you that like I said the movement pattern is important.
But on top, like you said skills are specific. In a lot of contact sports, track and field etc, force transfer of the legs to an opponent/your upper body/an athletic device is essential, to train your core and your legs seperate and then use time to try to integrate both skills seems time consuming or dumb im my opinion. Especially since the integrated movement of legs/hips/core is a basic skill you need to apply most of these specific skills.
Although coaches abuse cleans etc. (where sometimes the learning curve is too high and unneccesary) there is a reason most athletes use squats / cleans / powerlifts in their training, as they need the spinal stabilization and rigidity. A lot of people underestimate the force of that is produced by the legs and needs to be transfered by your hips and upper body or at least counteracted.
Research between jumping/sprinting performance and leg press/squat???

Stuart Gilbert said...

Can I clarify a point. mt response was based on your criticism of Bill DeSimone's ideas, and not on the issue of nerve damage. Can I also say that your area of concern, athletic development is not an area that Bill is aiming his work towards. His target audience seem to be the typical trainee, who is interested in lifeloand safe training, who have either suffered injuries, or who wish to play the percentages, and don't wish to accumulate any.
As far as athletic development, there are a good few NFL teams that do / have incorporated machine based training into their strength and conditioning work as well as / instead of ground based, free weight training. Could you tell which is which? Surely if squats were such a major factor, then the NFL would be raiding the Olympic lifting / powerlifting ranks for new talent. As Chris said, strengthen the musculature, THEN practice the skills. Specific is exact, not nearly....

Vijay said...

An old video of the current Superbowl Champions' strength coach. Also the assistant strength coach for the 49ers was mentored by Mike Gittleson and is the adopted son of Ken Leistner. Highest paid strength coach in college football also uses a lot of machine training. None of them are against squats however their methodology is also based on creating variety for their athletes so not to bore them. All them understand its all about creating the raw musculature for playing the sport and not developing skills. Obviously there are loads of different methodologies and philosophies in Football (gridiron) all having had success at the highest level.

Anonymous said...

Why does the conversation always end up being about athletes? I'm not an athlete and neither are the majority of others. It's a moot point to most of us so I don't understand why it's always made. If I had a team of people who could properly instruct me, correct imbalances, and ensure safe and appropriate progressions, the situation would be different; but I don't have that so it's irrelevant to me. What matters to me is what I can safely do either in my own home or at a commercial gym. In that context, the sqaut is a questionable exercise so questioning it's use is perfectly reasonable.

The problem that I see with many of these debates is that so many people forget that athletes make up a relatively small percentage of the population, and have access to trainers that most of us will never even meet let alone train under.

DFoltz said...

Does Bill have numbers?
I mean, my understanding is that since shear stresses are efficiently handled by the deep angled muscles of the spine, our concern is really with the moment developed, which is the integral of load over distance. Which, yes, increases as you integrate towards the lumbar region...

The thing is, looking at the pictures of spines these people wave around, what I see is a muscle attachment point on the dorsal surface which is a constant distance from the center of the disk "bearing pad". So the force on the disk is proportional to the applied moment; if it's the pressure on the disk (which seems reasonable to me) which determines how large this pad has to be, the diameter of the disk should be the square root of the applied moment.
So, if the spine can accept a moment which increases linearly along it's length, as it does when you load it with a barbell, the diameter of the disks would vary as the square root of the distance from the load. Which, again looking at these guys' own slides, it certainly looks like it does. (up to the T-C junction, anyways)
(if the spine should only be maximally loaded in the manner it would experience when you load it with a distributed load, like your bodyweight, the disk diameters would vary linearly with the distance from the shoulders) certainly looks to me as if applying force with the arms is the hardest thing you can do with the spine. (check out the EMG studies of spinal erector activation in biceps curls, for instance)


That said, the structures the backpack people are worried about are in the neck/traps and (mostly anterior) shoulder proper, not in the scapula, so while a high-bar squat might cause problems (I know they make MY arms go numb!) a low-bar squat shouldn't cause shoulder problems.


As an aside, The Thing I don't like about these "backpack" articles I've seen over the last couple years is that they never offer any solutions...
it's like everyone has forgotten that external frame backpacks exist. Per the ALICE manual, you'd get a 2/3rds reduction in loading by shifting the load to the hip belt.

Bill DeSimone said...

First time Anonymous wrote anything I liked. ;)

Look, gentlemen: if you want to squat with a barbell, be my guest. I personally won't, nor will any of my clients, because putting a bar on our backs could not be more irrelevant to us.
And in the Congruent Exercise manual, I didn't write "don't barbell squat". What I wrote was, IF you're going to, these are biomechanics and anatomy aspects to be aware of.
Which, btw, all the qualifications and precisions that the pro-barbell squatters bring up? Proves my actual point.
I'll agree that many leg press devices are poorly designed, but every barbell squat exposes the back to the same risks. So to be more precise "a properly designed and performed leg press is a safer and better choice than a badly performed barbell squat". Unless, of course, you disagree.

Bill said...

Let's not forget that most athletes are retired by their mid-30's.

I believe that this subject is a constant source of bemusement to Mr. DeSimone. The attachment some have to what is merely an exercise borders on the bizzarre.

I still throw in an occasional set of leg extensions. It's amazing that I still have to functional ability to bring the laundry up from the basement!


Jules said...

"However, it did make me think of the potential damage that could be caused by heavy back squats where you have large weights right on this sensitive area."

Harden up man. There is a large difference between a doing a heavy back squat and carrying a heavy backpack. You should be more worried about tweaking your lower back (squatting bad form) than any potential nerve damage.


"Let's not forget that most athletes are retired by their mid-30's. "

Haha. No. Take a second and look at the triathlete scene. You would be surprised.

Anonymous said...

@anonymous .

Why do have a problem with athletes being brought up? If you watched the video you'd realise there's nothing that they're doing that you shouldn't be able to do without a team of trainers. Completely rational style of training that could be used for the general population. In fact I would go so far as to say that the training that a lot of athletes do in the weight room is far more rational, safe and time efficient than what the general population. I know those who have no problem what so ever lifting in their 60's and 70's. Did they have a team of trainers to guide them there? These guys train more like athletes than the rest of the population.

Also if you're unable to correct imbalances in your body without a team of trainers behind you I don't know what you're doing even reading this blog. A bit harsh I know but Chris isn't exactly dumbing down his blog for the general population.

Anonymous said...

I'm going to try and explain this differently. If you were to maximally load your back and attempt to squat outside of weightlifting, and before the sqaut became a common exercise, you would be stopped immediately for fear that you would break your back. Now, I'm going to change the argument: are back sqauts really the best exercise for strengthening the quadriceps, as they're often used, or are they better suited to strengthening the posterior chain? Since the load transferred to the legs is in fact limited by the strength of the posterior chain, I would argue that most people are applying the back squat incorrectly. If we instead use the back squat to strengthen the posterior chain, I'm all for the it because then it would focus on strengthening the areas most susceptible to injury and most needed to ensure proper transfer of power when performing athletic movements. Using the back squat as an exercise to strengthen the legs however, will never be acceptable to me.

This is the way I now use the back squat myself, and I've found it to be a perfectly safe and effective movement doing so; however I strengthen my legs with other movements as those movements do not inflame my sciatic nerve and cause me to suffer unnecessary pain and lost time at work.

To answer your other question, Anonymous, it is impossible to ensure proper execution of the squat, when maximally loaded, while working independently. If you do not understand this, I'm afraid that I will never be able to properly explain it to you.

Anonymous 1

Anonymous said...

My apologies if I seem to be contradicting myself or trolling. I'm not particularly skilled at debating online.

Anonymous 1