Monday, November 17, 2014

Optimal Exercise: Joint Friendly Fitness

In October 2014 I gave a talk titled Optimal Exercise: Joint Friendly Fitness, for Anthony Johnson and the 21 Convention in Tampa, Florida.  The following is about half of the presentation, which makes for an introduction to the material I use in the studio Optimal Exercise in Cranbury NJ, and will be publishing in 2015. 
After a glowing introduction by Anthony, I started the talk by pointing to the other speakers in the room and saying...
Phd, Phd, Phd, Phd…Personal Trainer. Certified.”

I am a personal trainer and my specialty is Joint-Friendly Fitness.

This talk, and my work in general (video, blogs, books) is all about Avoiding Injury From Your Workout.

Which, for years, I didn’t think needed to be said.  What could be more counter productive than getting injured from an activity you do to benefit your body?
First tip, write this down: If you want to know what’s going to be successful in the future, ask me, and bet the other way.  Because the most publicized fitness activity today not only dismisses the risks from exercise, it glorifies the injuries.

Over the last year, catastrophic injuries have been reported coming out of a certain fitness activity.  I’m not going to mention the name for the same reason James didn’t.

These reports don’t come from bloggers looking to be provocative; these are actual news agencies.

The first, Outside magazine online, did a series of articles pro and con, and took great delight in reporting the over-reaction to the negative articles from the group in question.

The second, Time, ran a multipage article in its print edition last January; again, pros and cons, very balanced, very fair.
And the most recent, Outside the Lines on ESPN, did an investigative report.  Now this is interesting, because ESPN broadcasts the Reebok CrossFit Games, so this came very close to biting the hand that feeds you.  This report starts with a guy doing hanging leg raises in a Crossfit gym caught on security camera.  The hanging leg raises aren’t done in HIT or Slow style; he kicks his legs up to touch his feet to the bar, and then drops them.  Kick, drop.  He’s aiming for 40 reps, and with the instructor right next to him, encouraging him, at rep 30 his feet hit the bar, he lets go, lands on his head on a concrete floor, and literally bashes his own skull in to the point where he’s almost pronounced dead.  Somehow he survives, and tells the ESPN reporter, “Well, it almost killed me, but being in such good shape from it saved my life.  I can’t wait to get back.”
Now, to be fair, it’s not just Cross Fit.
In 2011, I started Congruent Exercise with 5 examples of catastrophic injuries coming from conventional bodybuilding and strength training.

First muscle magazine I ever read, opens up to the story of a Pennsylvania man found dead in his basement with a barbell across his throat.  He missed the bench press, bar stopped on his throat, choked to death.

The next, a bodybuilder named Fux, pronounce fuxxed, because that’s what he was.  Doing a photo shoot, puts 675 on a bar to squat, breaks the lock at the knees, tears both quadriceps, risking his ability to walk.

Next, a man squatting in a smith machine, no bottom stops, breaks the lock in his knees, continues to descend to where his spine gets crushed and turns into a quadriplegic.

A college football player doing barbell step ups, either twists his ankle coming off the bench or returning to the rack, injures his spine, again putting his ability to walk at risk.
Another bench press injury, a college football player benching, with the strength coach spotting, 275, misses the put back, drops the bar on his jaw, has to have emergency surgeries.  Later sued, not sure how it resolved.

So it’s not just CrossFit or bodybuilding or weight training in general, there are other things in play when it comes to injuries from exercise.

Now every time something like this happens, the apologists come out and say “it was a freak accident, we do that exercise all the time with no problem.”  Or they blame the victim for making a mistake or not knowing what to do or trying too much.  And yes, you could drop a weight on your foot, or the machine could collapse as happened to a friend of mine, so accidents do happen.

And, you may have a pre-existing condition that you may not even be aware of.  Maybe you wore out a joint at work, doing manual labor or some kind of repetitive motion.  Maybe you got banged up doing sports as a kid, and you didn’t realize the long term effect.  Maybe you had bad posture or just moved wrong for years, and you were going to have this injury at some point and it just happened during your workout.  Not much you can do about that.

Usually the discussion stops there, but there are other things in play that you can do something about.

All or nothing thinking: I’ll leave it to Eric for the proper term.  This is from a CrossFit age group champion.  Notice, in the first quote, he didn’t say, “…barriers to winning” or “competing”, he said “training”.  If you get hurt trying to win or qualify, that’s understandable, you got caught up in the competition.  But he’s not even there yet: “training”.  And the second part is the false choice: either exercise so recklessly that you cripple yourself, or shrivel up and die; nothing in between.  How about work out hard enough?  You might not become champion that way, but how many of us realistically were going to be champions anyway?

The Goldman Dilemma (Wikipedia): In the 70s a Dr. Mirkin put out one of the first pop sportsmedicine books.  His idea was picked up by another Dr., Goldman in the 80s and 90s.  Questions about their methodology aside, a lot of people answered yes, they would take the champion pill even if it killed them.  The first was a false choice, this is a personal choice.  I had the chance to use steroids in the 70s, and I didn’t.  Part of it was I didn’t know my natural potential; turned out, I may have had enough to make a mark in bodybuilding.  The other part was that one of the scare tactics around steroids was the threat of cancer, and since my dad was in the hospital at the time with cancer, this didn’t seem like a good bet.

And for what? A trophy?  Little did I know in the 70s, that within ten years, big money athletes, movie stars, performers would want information on how to use steroids.  My crystal ball sucked again.

But this last part, is something you can do something about, even if it’s only knowing the issues and how to manage them, and this is where I come in.

First, a brief background.  Started training with weights in the 70s.  Most of what you learned then came from the muscle magazines, which I may have memorized.  My favorite writer was Mike Mentzer, and his articles led me to Ellington Darden.  If I had stayed strictly with the exact words they wrote then I would have been a lot better off.  But novelty being what it is, I read everything and tried to incorporate and improve it.  I also got certified by the NSCA twice, Strength and Conditioning Specialist and CPT.  So I had a lot of influences and material to refer to.

The picture on the right, 1996, is the best shape I was ever able to get in before or since.  Notice I put it as far from Mentzer as possible.

Unfortunately, I couldn’t look exactly like that now, because in 1998 I ruptured my right biceps and triceps.

The triceps, I injured in a fall, nothing I could do about that.  The biceps, though, I was just doing a slow curl, when I felt a snap by my shoulder blade and felt slithering down my shoulder.  I looked, found a black and blue golf ball where my biceps used to be.  This somewhat got my attention, because as I said, I had a lot of exercise material to draw from and I thought I knew what I was doing.

It also got my attention, when after I recovered, on some exercises, I didn’t lose a thing, but on others I could hardly get into position or hold the position.

So I put my exercise books aside, and went to my physical therapist friends’ bookshelves  for anatomy and biomechanics books.  And that’s when I realized this disconnect between how muscles and joints are supposed to work and what I was doing in the name of exercise.  And this disconnect was in play not only for the catastrophic injuries but also the less dramatic injuries (like ruptured biceps) and chronic conditions (like low back pain, shoulder instability, arthritis, knee pain etc.).

So I rebuilt everything I thought I knew, which led to Moment Arm Exercise, a handful of You Tube videos, conference presentations, and Congruent Exercise (links for all of which follow below).

Biomechanics books are very dense, and they are not written with lifting things in a gym in mind.  So I eventually settled on this process as a way of giving it a practical structure.

As a way of sorting out all the biomechanics material, how I focused my study.

Before we head into a gym.
I frequently hear “That’s a good exercise/workout”, and if you pick at the answer, it usually means some combination of the aspects in the left column.
Now, I want that, too, but I also want the right side.  If you just have the left side, it doesn’t immunize you from injury.  But if you have both, you’ll get the benefits without risking the catastrophic injury, and not adding to the chronic conditions.
Two last slides to finish this introduction to Joint Friendly Fitness:


The best links to the material mentioned above:
The Moment Arm Exercise manual 
Congruent Exercise in print and Kindle 
Prior to 2011
All the presentations, a 15 minute post-presentation interview, and an hour discussion with Dr. Doug McGuff, Skyler Tanner, and myself were professionally recorded as part of the convention.  As they become available I'll be sure to post the links. Thanks to Anthony and his crew for putting on the convention.

Wednesday, October 29, 2014

Avoiding the Tragic Accident in the Gym

Given the reporting over the last year by Outside Online, Time Magazine, and Outside the Lines, on the brutal injuries coming out of a certain exercise activity, I thought this chapter would be worth revisiting. 
It is an excerpt from Congruent Exercise:  How to Make Weight Training Easier on Your Joints, (2012) available in print and Kindle at

1. Avoiding The Tragic “Accident”:
Biomechanics You Need To Know
The absolute first priority for anyone training with weights should be to avoid a catastrophic injury.  That should be obvious, but consider the following:
·         In 1972, Muscular Development magazine reported on a Pennsylvania man, found dead in his home, on his bench press, with the bar across his throat.  He apparently missed his lift, the bar landed on his chest, and rolled to his throat, strangling him.
·         In 2002, Flex magazine reported on a competitive bodybuilder, performing a barbell squat with 675 pounds for a photo shoot.  As he bent his knees, he lost control of the descent, landing on his knees, then falling backwards with the weight.  His quadriceps and patellar ligaments were torn, resulting in multiple surgeries, months of rehab, and putting his ability to walk at risk.
·         In 2003, Club Industry magazine reported on a lawsuit brought by a man using a Smith machine for squats.  He wasn’t able to control the descent of the bar, the machine did not have bottom stops, and so his spine was crushed between the bar and the floor, leaving him quadriplegic.
·         In 2007, a college football player, after performing the step-up exercise with 185 pounds on a bar across his shoulders, twisted an ankle returning the bar to the rack, and fell with the barbell.  He suffered injuries to his spine and, again, his ability to walk was put at risk.
·         In 2009, a college football player, bench pressing 275 pounds with a spotter, missed the lift, dropped the bar on his throat, and had to have 3 emergency surgeries on his vocal cords, adam’s apple and neck.
These instances, which involved a range of trainees from guys working out at home and in commercial gyms to high level athletes, are always reported as tragic, freak accidents.   And it is tragic that these people suffered life-altering injuries doing something that was supposed to be life-enhancing, and that clearly they weren’t intending on getting injured, so in that sense, these are accidents.
            But what is especially tragic is that even though these are standard exercises, the injuries they could cause are predictable and preventable.  An analysis of even the most fundamental biomechanics suggests that the “freak” occurrence is when you push these exercises hard and don’t get hurt.  Squats and bench press are especially dangerous, because your spine, and your throat, face, and jaw are between the barbell and gravity.  Here are the biomechanics you need to know to avoid a catastrophic injury:
·         Free weights “get heavier” as you bend.
·         You can lower more weight than you can lift.
·         The bones and muscles of the spine aren’t suited for top-heavy loads.
·         Balancing on one leg or a split stance relies on small muscles of the hip and deep muscles of the spine.
·         Putting the weight back relies on much smaller muscles than the ones that lifted it.   
Free weights “get heavier” as you bend.
            Anyone who has done a squat or bench press with a barbell knows this to be true.  Put the bar on your shoulders to start the squat, and while you’re standing with your knees and back straight, the weight is manageable. Same with the bench press, as you take the bar off the rack and your elbows are straight.  As soon as you break the lock at the knees and elbows, the weight starts to get heavier, becoming heaviest the closer you get to the bottom.
            But it’s not “heavier”; it’s the same barbell.  Something changed from lockout to sticking point, but it isn’t the weight.  It’s the moment arm, or the lever through which the weight acts.
            The clearest way to demonstrate Moment Arm is with a Seesaw.  Walk up one side of a seesaw (for demonstration purposes only, don’t try this at home) and stand directly over the axle.  No matter what you weigh, conceivably, you could balance both sides of the plank off the ground, because your weight is directly over the axis.  But if you take one step to either side, or even shift your weight, the plank tips.  By moving your weight away from the axis, you introduce a moment arm, making your same weight “heavier”.
 With the barbell squat and bench press, when the weight is directly over your joints, it’s the same as standing over the axle.  “Lockout” is the same as no moment arm: the axes are in line with the weight.   As you break lockout in the squat, and your hips move back, it has the same effect as stepping to the side on the seesaw.  Instead of the weight walking away from the axis (the seesaw), the axis is moving away from the weight.  Either way, a moment arm is created, and the weight gets “heavier”.
            The moment arms in the barbell bench press are less visual, but as you lower, the weight moves away from directly over the shoulders and elbows.  It’s easier to see with dumbbells.  Since hand width is fixed on a barbell, as the elbows bend, they also move away, so you get moment arms created at both sets of joints.  With barbells or dumbbells, the weights get harder to handle as they approach the bench presser.
            This easy-to-hard pattern is in play at all weight levels, but is obviously more of a concern at maximum efforts.  With a light enough weight, you could conceivably throw the weight off or push it to the side if you run into trouble.  As you approach your maximum, this becomes less of an option, and if you’re in a smith machine, it’s not an option.  Practically, this means you could guess wrong about your capability, put too much weight on the bar, start out ok, and then only realize, too late, that it’s too heavy. So the conventional squat and bench press with a barbell moves from easy-to-hard, mechanically.   There’s also a muscular aspect.
You can lower more weight than you can lift.
            Muscles are commonly described as having three levels of strength.  Positive strength comes from the shortening of muscle (a “concentric contraction”); an example of which is lifting a weight.  A higher level of strength is isometric (“static contraction”),   where the muscle exerts effort to hold its’ position.  The highest level is “negative” strength (“eccentric contraction”), which comes from allowing the muscle to lengthen under control. 
            Practically, in the gym, this has several applications.  Generally, if you’ve lifted a weight ten times, and can’t complete number eleven, you could stop your set at ten.  Or, you could begin rep 11, stall during the rep, and hold that position for as long as you can, extending your set.  And if you have attentive training partners, they can then lift the weight for you, so you can lower it under control, extending the set even further.           
            It could also go the other way (“negative training”), where you deliberately pick a weight heavier than you could lift and just do the lowering portion of the set.   If you can’t do a chin up, for example, you could climb to the top, and only do the lowering portion of the rep; which obviously allows you to work those muscles better than not doing any chin ups.
The issue with the squat and bench press, however, is if you don’t realize the weight is too heavy.
            For exercises where you lift, first, if you pick too heavy a weight, you know right away that you can’t do the rep.  Put 500 pounds on a bar and try to deadlift it.  Put 200 pounds on a bar and try to curl it.  You’ll know right away that the weight is too heavy, and generally stop before anything bad happens.
            With the squat and the bench press, you start at lockout, the mechanically easiest part.  You’re also starting with the lowering phase, where you can handle more weight than you can lift or hold.  You might actually be able to start the squat with the same 500 pounds you walked away from on the deadlift, and you might be able to lower it under control; but if you realize it’s too heavy, you may not be able to lift it, and you may not be able to stop it.  The same aspects of muscle strength that allow you to extend your set, and to practice chin-ups, even to walk down steps with little effort, can cause real problems on the squat and bench.
            Starting at lockout and doing the negative first apply to both the squat and bench press.  The squat has the added complication of involving the spine.
The bones and muscles of the spine aren’t suited for top-heavy loads.
            Take a look at the human skeleton, the spine in particular, preferably a rear or side view.  Starting at the pelvis and looking towards the head, we see three sections of vertebrae: 5 lumbar, 12 thoracic, and 7 cervical.  The size and shape of each is related to their function.  The lumbar are the biggest and strongest of the column with interlocking processes, preventing rotation.  This stability is to support the weight of the entire upper body. 
            Next up is the thoracic.  The lower vertabrae are about the same size as the lumbar, but each next, higher vertebrae gets smaller, as each supports less weight.  Each thoracic is not as locked in to the next, as the lumbar are, which allows for rotation.  We need more general mobility in the thoracic, compared to the lumbar, because this is also where the ribs attach, which have to accommodate breathing.
            The top section of the spine, the cervical, has the smallest vertebrae with the least amount of interlock.   These only have to support the weight of the head, and require the most mobility (as a unit)  of the three regions.
            Generally, the overall organization of the bones of the spine is a pyramid: stronger and thicker at the bottom, supporting less weight towards the top.  Practically, a pyramid provides stability: a broader base of support with a lower center of gravity means you can stand, walk, or sit with very little muscular effort. 
            Once you move, however, the pyramid is disrupted, and the muscles have to provide more stability.  Let’s look at the muscles around the spine, moving from deepest to most superficial.
            The deepest layer are the rotatores, each of which connect each vertebrae to the next adjacent, running almost horizontally.  Visually, these are stacked from top to bottom, and each individual muscle is very short.    Next are the multifidis, which connect each vertebrae diagonally to the next; also stacked top to bottom, and individually not as short as the rotatores.   Each individual muscle in these sets of muscles only connects one vertabra to the next.  The shortness of these muscles suggests that their function is not so much to twist the spine, as it is to hold the spine steady. 
            The most superficial layers, the semispinalis and the erector spinae, are individually longer, and connect over more than the next vertebrae.  Part of the semispinalis connects the head to different points in the thoracic; part of it connects the neck to different parts of the thoracic; and part of it connects the upper portion of the thoracic to the lower portion.  Parts of the erector spinae connect the pelvis and thoracic to higher points on the thoracic and cervical spine.   These sets of muscles, which can contract over a greater distance, seem more suited to moving the spine (although the functions probably don’t break up that neatly).
            Compare above the pelvis with below.  The pelvis itself is a pretty solid structure of few bones, each significantly bigger than any of the vertebrae.  On the back side, a big superficial muscle, the gluteus maximus, connects the pelvis to the femur, and the hamstrings (connect the pelvis to the lower leg.  On the front side, part of the quads (rectis femoris) connects the pelvis to the lower leg, while the rest connects the femur to the lower leg. 
            The system below the pelvis provides for speed and power: big, superficial muscles pull on few, solid beams of bone, moving through large ranges of motion, in few directions.  Above the pelvis, there’s no muscle match for the glutes or quads; and even if there were, the spine isn’t a beam like the femur.  With the spine, many muscles only have to hold or move slightly, the next vertebrae.  This system provides mobility, with stability, for the overall spine.
            What does this suggest about putting a barbell on top of the spine?
            With bodyweight alone, the muscles and joints of the spine are fully capable of holding the torso and head steady, while the bigger muscles (glutes, quads, and hams) move the legs and propel the upper body.  In this example, the spine does function as a “column”.  Manual laborers have known this for years:  “Lift with your legs, not your back”, means “hold your spine steady, while you bend at your hips and knees”.
            Put a barbell across your shoulders, however, and the situation changes.  Now, instead of a decreasing load from pelvis to head, we have dramatically reversed the load: even just a bar at shoulder level is significantly greater than the weight of the head.  Neither the muscles nor the vertebrae are structured to support this: the closer the vertebrae are to the head, the smaller they are; and there is no single mass of muscle connecting the lower vertebrae to the head and neck.   The same weight that is appropriate to challenge the glutes and quads, working through the largest, strongest bones and muscles in the body, also has to be supported by the dozens of smaller muscles around each individual vertabrae.
            Practically, if you squat with a barbell, your back muscles will get stronger, up to a point.  But the spine also has discs and nerves that are being loaded with the bar on your back, which doesn’t apply to the femur.   As the glutes and quads get stronger and need more weight to challenge them, your back is taking on more strain in a variety of ways.
            So the idea of working your lower body, by loading a barbell on your shoulders, is limited in several directions.  Don’t worry; it can get worse:  put a barbell on your shoulders and try to exercise one leg at a time.
Balancing on one leg or a split stance relies on small muscles of the hip and deep muscles of the spine.

A fundamental concept in biomechanics is relating your center of gravity to your base of
support.    You can stand on two feet and maintain your balance pretty much without effort, because your center of gravity falls within your base of support.  Pick one foot up, i.e., remove a support, and you should fall to that side, because now, your center is outside your single support. 
 Generally, though, we don’t, by unconsciously shifting our center of gravity away from the foot off the ground, and directly over the foot on the ground.  The function of the muscles on the side of the hip (gluteus medius and minimus), in spite of what’s implied by hip abduction machines, isn’t to pull the femur towards the outside of the pelvis; it’s to pull down on the pelvis, shifting the center of gravity towards that side.
            It’s not a dramatic shift; in fact, it’s barely noticeable.  If you stand, put your thumbs on the sides of your hip, and pick one foot up to balance on one foot, you can feel the muscle tighten and (if you avoid falling) feel your balance shift.  At the same time, the deep muscles around the spine, rotatores and multifidis, tighten, so when the pelvis shifts, the torso follows, maintaining the balance.
            The same shift has to happen with exercises.  Heel raises, split squats, lunge walking, reverse lunges, stepping up to a bench are all common exercises that disrupt your base of support.  Your performance of these exercises, conceivably for the prime movers of the lower body, is going to be limited by how well your side hips manage that shift.  This is not necessarily a bad thing, because aside from rowing and weightlifting, few sports and physical activities use both legs together as in a leg press or squat.  Your inner thigh and outer hip muscles will work extra to stabilize the femur, so the larger muscles can drive the limbs.  So you might trade off some intensity for the prime movers, for more stabilization, and in the long run it may even out.  The complications start when you try to add resistance.
            Using a barbell extends your mass so far to the sides that the normal shift of your center of gravity gets magnified.  Instead of your center of gravity being connected to your body mass, it’s now connected laterally to the ends of the bar.  If the bar isn’t placed exactly centered, or if the plates shift at all, or if the wind blows to one side, you don’t just have to manipulate your bodyweight; it’s your bodyweight, plus the extra moment arms created laterally.  If you lose your balance, you’re probably better off if the bar falls off than if you try to re-balance, because the spine is going to be unavoidably involved.  (Maybe not so good for other people in the gym.) 
            The safest way to load single-leg or split stance exercises with weight is by keeping the weight close to your center.  Weighted vest, one dumbbell on the working side, dumbbells in each hand, weight plate held across the chest, even a hip belt:  all these keep the weight closer to your center, and provide similiar work for the lower body stabilizers and prime movers.    
Putting the weight back involves much smaller muscles than the ones that lifted it.
            You have finished your set without incident.  Your muscles might be burning, you’re breathing heavier, you have barely locked out the last, most difficult rep.  Don’t relax yet:  you have to maintain lockout until the bar is physically supported by the rack.  Your prime movers are shot, so if the weight moves away from zero moment arm, that load is going to have to be supported by much smaller, deeper  muscles.
            With the squat, if you slouch, relax your gut, or bend forward to put the bar on the stand, the weight moves off center, and the deep muscles of the spine discussed above will try to hold things together. With any amount of weight on your shoulders, this puts the spine in a vulnerable position, so a weight that challenged your glutes and quads is especially dangerous.  You have to keep everything tight, walk as short a distance as possible to the rack, position the bar directly over the rack, then set the weight down.  Now you can collapse.
            The bench press is a bit more complex. Many bench press stations have too much height between the bench and the rack, so you either need a lift off from a partner or you hunch your shoulders forward to get the bar.  Bench pressers usually position themselves away from the rack, so it doesn’t interfere with the path of the bar; but this means the bar has to move over your forehead, face, jaw, and throat before getting set to press.
            This is manageable at the start of the set, but when you’re done, you have to reverse everything, and this is where the problems are.  At the end of the set, you’re locked out: the pecs and triceps are shot, but you can still support the weight.  Since the rack is “overhead”, you have to move the bar away from directly over your chest, towards the rack.  Even though your elbows are still locked, you create a new moment arm, so again, the same weight gets “heavier”.  Only now, the weight is over your face, and your pecs and triceps are spent. 
            At the same time, you have to raise the bar to clear the rack.  If you lift your shoulders off the bench (protract the scapula), you use the serratus anterior and pectoralis minor.  Since both are deeper and smaller than the pectorals, in order for them to move the same weight that exhausted the pectorals, they probably have to heave, not lift under control.  The combination of exhausted prime movers, deep muscles trying to move big weight, a new moment arm, and being pinned in place can be a disaster.
            A single human spotter may not be much help.  Usually the spotter stands centered between the stands, but away from the path of the bar.   If the bench presser misses the rack, or gets stuck at the bottom, the spotter has to be able to power clean or deadlift the bar, quickly.  I especially like the 200 pound bodybuilder being spotted by the 135 pound partner.  Unless that 135 pounder can clean 300 pounds, the best you can hope for is the 911 call. 
            Ideally, once you finish your set, you stay locked with the weight above your chest, without trying to lift your shoulders or lean the weight towards the rack, while spotters lift the weight to the supports.  The minimum setup is to have two, one at each end, to lift and place the bar on the rack, or to hold it off you while you scramble.  The best is to have a third, centered, who can steer the bar.
Practical steps to avoid barbell catastrophe
            If your tool of choice is the barbell, whether by necessity or preference, you have to take precautions, especially with maximum efforts.  You may still get hurt with submax efforts, and you may still get hurt with the precautions in place, but probably not with permanent, life-altering injuries.
 Center the bar, and always use collars.  Deep muscles make small adjustments for centering and balance.  Extending the weight laterally makes excessive demands on them, that will probably never come up in any other context, and is too risky.
Use structural barriers to avoid being pinned by the barbell.  Horizontal rails should be sturdy enough and set high enough to keep the bar off you.  If you use a smith machine, the bottom stops must be set no lower than the sticking point; don’t rely on the hooks.
Use a minimum of 2, preferably 3, human spotters who are paying attention. One at each end of the barbell, to catch and lift it off you, and a center one to steer, either the barbell or you out of the way.
Stay tight at the end of the set.  Even with locked knees and elbows, you can still make the weight “heavier” by accidentally creating a new moment arm, which would risk straining the deep muscles and worse. Maintain your posture until the bar is placed in the supports.
To load single-leg or split stance exercises, keep the weight close to you, or use other techniques for progression.    Keeping the extra load close to the center mimics the natural balancing more than the extended weight on a bar.  You may choose  less risk over more load, and use bodyweight alone, for more reps and sets, and less rest.
Of course, the most direct way to avoid injury with a barbell is:  Don’t put a barbell over your spine, face, jaw, and throat.  If you’re open to the idea, that is.
            For many people, even if the barbell was capable of delivering unique, phenomenal benefits, the risk simply isn’t worth it.  There are other, effective ways of working the same muscles, and safer, more appropriate ways of loading joints than with the barbell squat and bench press.  The barbell is a perfectly adequate tool, especially compared to what was available before it, but it’s not magic or super-science. 
            “Conventional wisdom” has created an aura around certain exercises and approaches that isn’t necessarily supported by basic biomechanics.  Weights load limbs; deep muscles stabilize joints, so superficial muscles can move the loaded limb; and bones at the joint move in relation to each other.  This happens whether you use a barbell, bodyweight, a weight stack, or a rock.  There’s no magic attached to one technique or tool vs. the other.  There are, however, specific, documented ways that muscles and joints are supposed to function, and walking into a gym doesn’t change that.
            Avoiding catastrophe is really the least you can get out of applying biomechanics to weight training.  You can also cut down on unnecessary strain on the joints, and load the muscles more effectively.  Fortunately, the two go together.
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