Squat Mechanics: A Deep Analysis

 

by Mark Rippetoe | 01/15/15

 https://www.t-nation.com/training/squat-mechanics-a-deep-analysis

Here's what you need to know...

1. When you squat, use your hips. This will require a more horizontal back angle than you think.
2. You may have heard that you must stay upright when you squat, with as vertical a back angle as possible. You've heard wrong. Think "rigid," not "vertical."
3. The angle of hip flexion must equal the back angle if the spinal relationships are to remain neutral.
4. The cue to "Point your nipples at the floor" works very well for the squat.
5. Looking up when squatting does nothing but fight against the correct back angle. Look down.
6. If your hamstrings get sore when you squat, you're doing something wrong.

The #1 Squat Mistake

Every seminar we hold is attended by people who have read the book, who have been training with the material for various lengths of time, and who are interested enough in what we have to say that they have paid money to hear it from us directly.

Yet every Saturday morning's squat session on the platform involves deprogramming the too-vertical back angle of essentially everybody who attends. Almost everybody. Why?

I don't know. I thought I had been clear. If the bar is to descend, it is necessary for the hips and the knees to bend. This can be accomplished in several ways, but as you'll see, the movement of the hips should be the primary emphasis.

In order for the hips to be the focus of the squat, the back angle has to facilitate a hips-dominant movement. The load is placed on the hips by lengthening the moment arm on the hips and back and shortening the moment arm on the knee.

This reflects the anatomical relationships of the knees, hips, and back, their respective muscle masses and leverages, and allows the most muscle mass to be affected by the movement over the greatest effective range of motion. It turns the squat into a hips-dominant back exercise that carries the legs along for the ride.

Everybody who comes to a seminar has read the arguments and knows our analysis. But somehow, this critical detail is getting misinterpreted, misunderstood, or just ignored.

Are You Front-Squatting Your Squat?

We go through about 5 hours of lecture prior to the practical session that deals with the hip's function and the physics of moment forces, yet enough people still try to front-squat their squats that correcting it takes a significant amount of time on the platform.

Our job is to correct things like this, and we do, I assure you. We've had a lot of practice. And once we get it corrected, you always tell us that it works much better this way. So maybe it's time to clarify so that my obviously obscure point becomes less obscure.

Use Your Hips. Really.

When you squat, use your hips. This means that you'll have to use a more horizontal back angle than the one in the picture in your head.

You know that picture of the squat you carry around with you, from watching Olympic lifters front squat or doing their "Olympic" squats that are supposed to be more "athletic."

Maybe it came from reading Muscle & Fitness or any of the other newsstand exercise publications at the cash register, while you were waiting to pay for your skinless chicken breasts and rice. Or maybe it was taught to you by an expert CrossFit Level I coach, who thinks that a squat finally "matures" when you can lead with your chest with 185.

You may even have read that elite powerlifters squat with a vertical back – some of them do, especially the ones who lift with a sumo stance in a monolift, in the triple-ply suit-and-wraps recreational federations that don't judge depth.

The correct application of the hip-drive model entails assuming the correct back angle and knee position for the bottom of the squat by the time you're about half-way down, and holding it as constant as possible until you get back to that position on the way back up.

For most people this will mean that establishing this position requires the knees to travel forward and out to a point approximately vertical to the toes (this position in a below-parallel squat will obviously depend on anthropometry), while simultaneously driving the hips back.

Our stance places the toes out at 30-35 degrees so that all of the lateral and medial hip musculature that maintains the femurs in external rotation is involved in the movement, so knees must usually be shoved out to keep the thighs parallel to the feet.

Knees outside the toes is a common misinterpretation made by exceptionally flexible people. Straight thigh/foot alignment keeps the knees and ankles from any twisting that a misalignment can cause.

At precisely the same time the knees are traveling forward and out, the hips are moving back into their position of loading. They move back because the bar must stay over the mid-foot for balance, and if knees move forward a little, hips must move back more to compensate.

"Hip flexion" is the proper term for this movement, and making up new words, like "hinging," is just not necessary.

Your Back Will Be Okay. Really.

I think the problem we see on the platform arises from a misunderstanding about the nature of spinal loading during hip flexion. The Forces of Darkness have done their job well, and they have implanted the notion that you have to stay upright when you squat, with as vertical a back angle as possible.

And I'm telling you to wipe this silly bullshit from your mind. Think "rigid," not "vertical" when you squat.

A strong isometric contraction of the muscles surrounding your spine keeps your back in Normal Anatomical Position – flat, as we say in the business, because a muscular lower back will appear flat across the top of the muscles as they hold a normal lordotic curve in the spine – and a flat back is both an efficient transmitter of force and a safe position in which to be loaded.

You have been told that a more horizontal back angle exposes the spine to something called "shear," an apparently fatal situation that arises when the back bears weight at an angle.

From previous discussions, you know that moment – or leverage, the force transmitted along a wrench that causes a bolt to rotate and the force that the barbell applies to your back during a squat – is a "shear" force, since it's comprised of forces acting in two co-planar directions within the stressed object.

In the squat, the moment force on the back is comprised of the force of the weight of the bar pushing vertically (gravity, right?) down on the back, which is held at an angle, and the force that's applied through the back in the opposite direction to resist the weight and move it through the range of motion.

So it's correct to say that the back is "under shear stress," because moment is a shear force. It's incorrect to say that if you walk outside when it's cold, you'll get sick because you were warm, then cold, then warm again: the Temperature Change Theory of Disease.

It's also just as incorrect to say that the back "will shear" – the use of "shear" as a verb that means one segment sliding past another along their shared plane – during a squat, since that cannot and will not happen.

Amazingly enough, mechanisms exist to prevent this from happening, due to the fact that it would have been inconvenient during human evolutionary development towards a bipedal posture if the spine had come apart every time it was loaded at an angle. You can see how that might have happened occasionally over several million years.

Absent the spinal condition known as "Spondylolisthesis," the vertebral bodies cannot slide past each other because these posterior structures of each vertebral segment overlap the one underneath.

Try as I might, I can't find a single reference anywhere to a thoracic or lumbar spinal cord/cauda equina injury sustained during properly supervised and performed squats and deadlifts (note the emphasis). We did find one case of a bad cervical injury that was associated with "weight training" – perhaps looking up isn't the greatest idea.

But during the entire time I've been teaching people how to lift barbells, since 1978 and not always correctly, I've never heard of such a thing, certainly not from anyone I've coached or taught to coach. People are remarkably diligent when it comes to telling you about spinal cord injuries they sustain as a result of your advice, and I've had no reports.

I'm not saying that spinal cord injury during strength training using the correctly-performed squat (note again the emphasis) hasn't happened. I'm just saying that had it happened, we'd probably already have heard about it.

So I'm not quite sure why all these Physical Therapists, personal trainers, and Certified Strength and Conditioning Specialists are so concerned about something that probably hasn't ever occurred, and why they don't seem to understand that your back adapts to the stress of training just like everything else does. Truly puzzling.

Round Is the Real Problem. Really.

In the real world, when the back fails to do its job of efficiently transmitting force in a squat or pull, it fails in flexion – it rounds over, out of extension, due to the failure of the posterior erector muscles to maintain sufficient isometric force production during the movement.

At the level of the flexing spinal column itself, like a loaded beam, the posterior (top side of the back when you're bent over in a squat) components are placed in tension as they tend to elongate around the convex side of the curve, while the anterior (lower) components are loaded in compression as they mash together on the concave side of the curve.

A flexing spine could smash the anterior side closed and stretch the posterior side open, producing the possibility of a disc injury. But actually, spinal flexion under load is not so much dangerous as it is inefficient.

After all, you've been picking things up off the floor with a round back for a long time, and you probably haven't been killed. Of course, those things were very light relative to a heavy deadlift.

We save permission for rounding the back under the bar for the 3rd attempt at the meet. Sometimes a limit attempt will be done with less-than-perfect technique, and competition is the place to assume the risk of doing it "wrong." (Don't tolerate it in training, or your back will never get strong.)

More importantly, if the back stays rigid, all the force gets from the extending hips and knees to the bar on the back, efficiently. A flexing spine leaks some of the force into the changing geometry, meaning that the knee/hip extension doesn't all get to the bar.

When we lift weights, we fight moment forces with the tools at our disposal. Our tools are the tension-producing contractile mechanism of the muscles and the structural form, rigidity, and hardness of the bones that act as levers in the system.

In fact, within the correctly extended spine during a squat or pull, each vertebral segment is held in neutral compression along the spinal axis by the isometric contraction of the muscle mass that keeps the spine rigid.

The erectors, abs, and all the surrounding musculature squish the column down into a compression load, which increases as the changing angle of the segment increases the moment force.

The resulting rigidity of the trunk segment enables the entire structure to function as a solid bar to transmit moment force between the hips and the load. If you keep your back in rigid extension, the back is loaded as a solid segment, not as individual vertebral components.

A tight, flat, rigid back therefore holds all the vertebral components in their normal relationship with each other, and this prevents both injury and loss of force transmission. If the intervertebral discs receive the same force across their inferior and superior articular faces in an anterior/posterior direction, they don't get hurt.

Back and Hips Together

So, when you squat, you're going to use your back. Get used to the idea that the back must be locked – and I mean locked tight and flat – into a rigid bar when you squat.

If it is, the back angle is not your concern, since the back is okay at an angle if it's rigid. But the angle of hip flexion must equal the back angle if the spinal relationships are to remain neutral.

Read that again: here's the conceptual problem you've got to fix. If you're going to flex your hips to use them in the squat, you must also bend over enough to keep your back in its normal anatomical relationship with the pelvis if you're going to use the back as a safe and efficient transmitter of moment force between your hips and the bar.

In other words, your isometric contraction around the spine that locks the back rigid and aligns it with the pelvis protects the spine, not a more vertical back angle.

A vertical back is not a "functional" position for either the hips or the back. You cannot lift anything – a loaded barbell or a bale of hay – in this position and keep it in balance over the mid-foot. Eliminate this flawed thinking, and make up your mind that when you squat you're going to use your back.

You're going to keep it flat, make it strong enough to stay flat, and make it do its job as an efficient transmitter of force between hips and barbell.

This means that you're probably going to have to bend over more than you want to. We've found that the cue to "Point your nipples at the floor" works remarkably well. Everybody has them, everybody knows where they are, and everybody knows which direction they're pointing at any given time.

And it's also very interesting that our recommended eye-gaze direction reinforces this position. Looking at the floor directly in front of your feet makes this back angle much easier to obtain and hold throughout the movement. It keeps your cervical spine neutral, and orients the rest of your spine correctly.

Looking up at the wall or the ceiling does nothing but fight against the correct back angle. So don't do it. Look down, you hard-headed assholes.

There Will Be No Good Mornings

Many people seem to be afraid of good morning-ing their squats. Perhaps they have read criticisms of our low-bar method of squatting from young geniuses on the internet who think that only since SS:BBT was published have people been using a more horizontal back angle to squat.

The most common mischaracterization of the technique is to equate it with the good morning, a barbell exercise in which a changing back angle through the range of motion is the loading mechanism:

I shall reiterate: The correct application of the hip-drive model entails assuming the correct back angle and knee position for the bottom of the squat by the time you're about half-way down, and holding it as constant as possible until you get back to that position on the way back up.

Nearly constant: the initiation of the movement out of the bottom with the hips will look like a very small change in back angle as the hips lead out of the hole. This is actually produced with a very slight knee extension.

Hip-bone's connected to the knee-bone, as it were, and if the hip comes up a little, the knee will have moved back, a little. This slight knee extension is essentially a quadriceps contraction, an obviously important part of the squat, but you think about it proximally even as it is a distal action.

Thinking about leading straight up with hips instead of thinking about extending the knees is the important thing going on in the lifter's mind that keeps the motion from turning into a good morning, which happens sometimes when the lifter moves hips back instead of up, and the knees have extended excessively.

If the back angle changes to the extent that the bar drifts forward of the mid-foot balance point, or if too much back angle is lost horizontally, it changes the mechanics of the lift. And if it's excessive, it will change what's essentially an isometric hamstring function – that of maintaining the back angle – into an eccentric lengthening, which is what a good morning actually is.

If your hamstrings get sore when you squat, this is probably what you're doing.

Dem Bones

But thinking about lifting the chest first pulls the knees forward – chest-bone's connected to the back-bone, back-bone's connected to the hip-bone, hip-bone's connected to the knee-bone – and this closes the knee angle.

Knee flexion (loose knees) slacks the hamstrings in two different ways. First, knees-forward coming into the bottom with a vertical back angle, like a front squat, slacks the hamstrings quite a bit from both proximal and distal ends. A closed knee and an open hip place the hamstring in the shortest position it can occupy while you're standing on the ground.

If the bar is to stay over the mid-foot with the back held more vertical, the knees must slide forward more than they have to in a squat done with a more horizontal back angle. In either squat, this knee placement should take place by the time you're about halfway down, just like the establishment of your back angle.

Many lifters make the mistake of allowing the knees to slide forward at the bottom of a back squat, and the mental picture of a chest-up position is usually responsible.

Knees forward is required for an Olympic lifter, who's trying to rack a clean on his shoulders with a vertical back as fast as he can get under the bar – it's a submaximal squat anyway, and you don't have to front squat a submaximal weight with much hip.

Speed is far more important here than anything else, and loose stuff can be moved around faster than tight stuff.

The moment arm the hamstrings support in a front squat is very short, because the back is vertical and the bar is therefore close to the hips. But trying to back squat a heavy weight with slacked hamstrings is terribly inefficient. It can be done, but it's not optimal.

Second, lifting the chest in the middle of the movement, on the way back up, slacks the hamstrings a little, primarily from the distal end, killing the hamstring tension necessary for maintaining the longer moment arm on the back and hips. Keeping the knees "tight" – staying in the hips – keeps the back and hip musculature engaged in the squat.

The large muscle mass actively used in this way is why we can squat more weight than we can front squat. The contractile mass of the quads is less than the contractile mass of the posterior chain musculature, and using both quads and posterior chain to their maximum capacity is more efficient than leaving out some of the posterior chain.

Dan Green World Record Squat

Scott Cartwright 1,025lb. Squat

These squats probably represent a comparable effort, given the differences in gear. Compare the lifters' knee position during the ascent, and note the depth and bar speed in both squats.

Moving Knees Leak Power

Both mistakes involve too much knee movement. Moving knees leak hip power. The correct movement is "all" hips.

Specifically thinking about holding the knees still at the bottom while "bouncing" off the hips behind you can be a good cue to fix this. Placing the knees where you want them as you set the back angle half-way down, holding them tight, and driving up with the hips can correct both problems.

The knees will move a little, but the idea is for them to move just enough, at the right time, by focusing on force production at the hip, facilitated by "frozen knees," or "tight shins," or whatever cue works best for you.

In practice, the coach looks for a very slight hip lead, the lifter thinks about driving the hips straight up, and the system stays nicely in balance as the lifter stays "in the hips" all the way up while maintaining a constant back angle until it's time to stand up straight, when you get back to about half-way up.

There's no good morning-aspect to this squat if it's done correctly, as fun as it might be to say there is.

The correct squat places the back angle in line with the hip angle for the best use of hip drive during the squat, and places the bar directly over the mid-foot for the most efficient mechanical execution of the movement.

A more horizontal back angle uses both quads and posterior chain to their maximum capacity, while a more vertical back angle restricts the potential of the posterior chain muscle mass to contribute to the movement of the weight.

Get used to the idea that your chest is pointed down when your back is horizontal enough, and that your downward eye-gaze direction anchors the movement. It will speed the process on Saturday morning. 

Related:  CrossFit & "Functional Strength"

Related:  Mark Rippetoe on deadlift mechanics

Related:  The Texas Method

Почему во сне немеют руки?

 

С вами когда-нибудь случалось подобное? Вы  спокойно спите и вдруг просыпаетесь из-за неприятного ощущения покалывания в руках. И так по несколько раз за ночь, вам приходится прерывать свой сон из-за того, что немеют руки, вам непонятно и обидно, согласитесь, а особенно это раздражает, если повторяется регулярно. Но в чем же причина? Существует ли решение этой проблемы? Сегодня мы все объясним.

Онемение рук и судороги могут возникать из-за естественных причин: неудобного положения тела во время сна: например, когда есть препятствия для нормальной циркуляции крови. Но иногда эти неприятные ощущения не имеют никакого отношения, к тому, как мы спим, более того, они появляются и в других частях тела, в ногах и ступнях. Давайте посмотрим, каковы причины этого явления.

Причины онемения рук

Запястный туннель

• Это, вне всяких сомнений, является наиболее распространенной причиной онемения рук. Наши три основных пальца на руках (большой, указательный и средний), часто страдают от так называемого синдрома запястного туннеля. Речь идет о проблеме, связанной со средним нервом, периферической нейропатией, которая создает давление на запястье, вызывая сильную боль или онемение, ограничивая подвижность кисти и пальцев рук, заставляя нас терять чувствительность. Просто в ночное время все чувства обостряются, поэтому и этот дискомфорт нам особенно неприятен.

Издержки работы

• Иногда мы слишком перегружаем себя, свои руки и запястья в частности. Такие виды деятельности, как долгая работа за компьютером (набор текста), шитье, работа с инструментами и даже с простыми ножницами… могут привести к тому, что нервы в наших руках не выдержат. Если часто сгибать и разгибать запястье, постоянно напрягать его, то неудивительно, что впоследствии возникнет чувство боли, которое сильнее всего проявляется именно ночью, когда мы уже не выполняем никаких движений, а нервы и сухожилия пытаются «расслабиться» и снять с себя любое давление.

Задержка жидкости

• Избыточный вес, отсутствие физических упражнений и неправильное питание могут привести к возникновению отеков, причем не только в ногах, как это обычно случается, но и в руках, и все это из-за задержки жидкости в организме. А покалывание всегда сильнее ощущается в ночное время суток, так как циркуляция крови замедляется, давление усиливается, а вместе с ним и чувство дискомфорта.

Недостаток витаминов группы В

• Часто, придерживаясь недостаточного или неправильного питания, мы не в состоянии обеспечить свой организм достаточным количеством витамина В. Недостаток этот приводит к определенным последствиям, но мы не всегда уделяем им должное внимание: думаем, что просто устали на работе, опять и опять, даже не догадываясь о настоящей причине такого состояния. Усталость, сонливость, бледность кожи, тахикардия, а также онемение в руках и ногах — очень распространенные симптомы в данном случае. Вот вам и еще одна причина.

Средства от онемения в руках

• Выпейте перед сном одну столовую ложку льняного масла.По данным ряда проведенных исследований, это очень эффективное средство, оно оказывает противовоспалительное действие (особенно в конечностях), облегчая состояние, если немеют руки.
• Опустите руки в раковину, наполненную водой. Если сможете, опустите их по локоть, так будет более результативно: вы сможете снизить давление, и, соответственно, воспаление нерва уменьшится и боль утихнет. Выполните эту процедуру непосредственно перед тем, как идти спать, и вы почувствуете облегчение.
• Постарайтесь уменьшить потребление соли и кислых напитков. Эти продукты способствуют развитию воспалительных процессов и обостряют болевые ощущения.
• Не забывайте, что ваш организм нуждается во влаге, поэтому следует выпивать не менее двух литров воды в день. Можете приготовить себе напиток из артишоков, к примеру, так вы сможете одновременно извлечь для себя выгоду и из его мочегонных свойств, избегая, таким образом, скопления лишней жидкости в организме. Для этого вам нужно просто вскипятить воду, добавить туда пару артишоков и затем процедить. Потом вы можете смешать получившийся напиток с соком половинки лимона для придания вкуса.
• Очень важно включить в свой рацион витамины группы В.Тунец, картофель, бананы, а также все зеленые листовые овощи помогут вам восполнить недостаток этих витаминов. Также в аптеках вы без труда сможете найти витамин В в таблетках, которые облегчат ваше состояние в ночные часы.
• Если ваша работа требует от вас постоянного движения рук, то есть в течение нескольких часов подряд вы вынуждены держать их в напряжении, можете воспользоваться какими-либо компрессионными браслетами для запястий (бандажами). Это обеспечит необходимую защиту вашим суставам и нервам и убережет их от перенапряжения.

Deconstructing the Deadlift /// A Deep Analysis of Proper Deadlift Mechanics

 

by Mark Rippetoe | 06/29/15

 https://www.t-nation.com/training/deconstructing-the-deadlift

Here's what you need to know...

1. "Rigid body" analysis - where the shape and dimensions of a body are considered to be constant and undeformable regardless of the forces applied to it - is useful in the analysis of complex human movement, like the deadlift.
2. The Standard Pulling Position is where the bar travels up the legs in a vertical line over the middle of the foot. The shoulders stay just forward of the bar until the top of the pull.
3. The most efficient way to pull a barbell is straight up. Always.
4. A correct deadlift will start with the bar about one inch from the shin, placed with the shin in a perfectly vertical position.
5. The heavier the weight the more efficient the pull must be. Warm-ups can be done "wrong," as can rows, cleans, snatches, and anything else with a light weight.
6. Looking up when deadlifting is a common mistake.
7. The alternating grip allows you to pull more, but it can cause injuries.

Warning: Dry technical article. Very little cursing, no bashing, no actual controversy. Just logic and analysis. Caffeine will be helpful.

"Rigid Body" Analysis

The human skeleton is the system of levers that we use to interact with our physical environment.

It's operated by a system of "motors" - little tension engines called "muscles" that operate the levers of the skeleton by generating a contractile force.

The details of the operation of this physical system can therefore be understood through analysis, and these details can be as complex or as general as the level of the analysis.

With more than 600 muscles and 200 bones, things can get very weird. Or they can be rendered understandable by pulling back a little and viewing the system as a chain of segments that transmit the force generated by the groups of muscles that operate them.

Running, jumping, throwing, swimming, and hitting a ball are fantastically complex activities if all of the constituent muscles and bones must be enumerated, each of their contributions to the functioning kinetic chain considered, and their individual force-production/transmission roles calculated.

It's not only impossible with our current instrumentation, it's rather pointless, because enumerating the individual contributions of the forearm muscles and bones of the wrist to a racquetball serve don't help us serve the ball, or learn how to do it better.

Movements become analyzable if you consider them at the macro level - the functional segments of the body operating against the resistance of the implement or the ground, and the primary muscles responsible for their operation.

The concept of "rigid body" analysis - where the shape and dimensions of a body are considered to be constant and undeformable regardless of the forces applied to it - is useful in the analysis of complex human movement.

A stride in a sprint is a hip/knee extension with a contralateral hip/knee flexion. The kinetic relationships of the feet, shank, thigh, trunk, and arms are complex enough without having to enumerate the roles of their constituent components.

In coaching the sprint we're primarily concerned with the force production and transmission relationships of the segments themselves, and we're less concerned with their internal components.

It's important to understand what the calf muscles, quads, hamstrings, glutes and adductors, spinal erectors, and shoulder girdle muscles are doing, because this understanding informs us about force production within the functional segments.

It isn't as important to detail the mechanical function of the obturator, the peroneus longus, or the long head of the triceps brachii in the sprinting motion, or their respective percentages of force contribution at any given point of their participation in the movement.

Their functions become important to consider in the event of an injury, and an informed coach knows enough anatomy to understand these functions, but we don't single them out for training because they're worked along with the primary muscles as they fulfill their anatomically-determined role in the correctly-performed gross motor pattern.

More important are the feet, shank, thigh, trunk and arms during the development of the acceleration as revealed by the analysis of their relative angles and their relationships to the ground.

The individual muscles that make this happen are not of concern during the execution of a record performance, unless one of them fails due to injury.

Strength training has long been the victim of a lack of focus on the movement patterns of the segments of body itself, in lieu of the great deal of attention being paid to the constituent components - the "muscle groups" of bodybuilding-think.

Let's examine your favorite and mine, the deadlift, from the perspective of rigid-body analysis, and see if we can't come to a better understanding of what actually happens when a bar is pulled from the floor.

The Mechanics of the Deadlift

An examination of men's division deadlift records on video will show you what you need to know about the relationship between the loaded barbell and the lifter: the barbell travels up the legs in an approximately vertical line over the middle of the foot, while the shoulders stay in a position just forward of the bar until the top of the pull.

And this is true no matter what the lifter attempts to with the bar; you may start somewhere else, but you're going to end up doing the pull this way.

We call this position The Standard Pulling Position, because, as we'll see, it results in the most efficient pull for deadlifts, cleans, and even snatches.

(The reason why women's deadlifts don't always obey this rule has to do with the same reason women can perform a much higher percentage of their 1RM for reps, but that's a subject for another article.)

It's important to know why this amazing lack of variation exists in pulling a heavy barbell from the floor, because if we know what's going to happen when we pull a heavy deadlift, we can make better plans for making it happen with the greatest level of reproducible efficiency.

If you know that the barbell is coming up in a straight line over the mid-foot, you can practice placing it in that position and keeping it there.

And if you know that the shoulders are going to be a little forward of the barbell when it leaves the floor, you can make plans to have them in this position when the pull starts.

Related:  Squat Mechanics: A Deep analysis

Knowing why is good, because it convinces you that correct technique is important.

It's not nearly as important to know what role the individual forearm muscles play in the effort, or the obturator, the peroneus longus, or the long head of the triceps. They're working, and good deadlift technique is designed to make them contribute to the pull.

But more important is the overall relationships of the major segments of the kinetic chain to the load on the bar.

Why Vertical?

Gravity is the force that makes mass "weigh" what it does. It's the attraction between two masses.

In the case of the earth, it's really really big relative to the barbell, so the attraction between the two masses is heavily skewed.

Since the attraction is between the two Centers of Mass, the center of the barbell and the center of the earth have a very predictable relationship: gravity operates on the bar, and it does so as a downward pull, in the precise direction of the center of the earth's mass. Always.

We call this direction "vertical."

As a result, work done against gravity is always performed vertically, upward. Always. All work done against the gravity vector will be done parallel to that vector in the opposite direction. Therefore, the most efficient way to pull a barbell is straight up. Always.

This will be the shortest explanation in this article. Sorry.

Why the Mid-foot?

A correct deadlift will start with the bar about one inch (2.5cm) from your shin, placed with the shin in a perfectly vertical position. This will place the bar directly over the mid-foot, for everybody.

Human feet are quite thoroughly proportional, front to back, and we've seen people with size 3 to size 17 shoes position the bar over the mid-foot with it placed an inch forward of the shins.

Once the bar is over the mid-foot, turn your toes out a little, maybe 15 degrees.

When this position is taken and the knees are dropped forward and out a little, so that the shins touch the bar without moving it and the knees stay parallel to the toes, the shin angle will be perhaps 7 or 8 degrees forward of vertical.

The knees-out position allows you to use the hip external rotators more effectively when you pull, and it also makes more room between your thighs so you can set your lumbar extension more effectively.

Knees out also involves the adductors in the pull as well, by stretching them into a position where they can more effectively participate as hip extensors.

And the slight shin angle allows the quads to perform enough knee extension to help with the start of the pull. Knees any more forward than this will cause the shins to push the bar too far forward to pull a deadlift. Here's why.

The foot is your point of contact with the ground. If the bottom of your foot was an arc, as though you were standing on a 12-inch piece of pipe that was split down the middle into halves, the mass of the system would be in balance directly over the center of the arc - your mid-foot.

If you were in good balance, you could squat down and stand back up by keeping your center of mass directly over the middle of the arc. Even though your feet are essentially flat against the ground, the balance relationship is clearly the same.

The surface area of the feet is the area across which the load of the combined mass of the barbell and your body is distributed against the floor.

A man with a size 11 weightlifting shoe will have a surface area of about 90 square inches (580 cm²), or an average of about 5.5 pounds per square inch with a 500-pound deadlift (3.84N/cm²).

At 800 pounds, the load is closer to 8.9 PSI. If the barbell is placed in a position halfway between the toe and the heel, the average load across the contact surface will be fairly evenly distributed - "balanced" - between forward and aft sections of the foot.

If the most even pressure distribution occurs with the load at mid-foot, positions either forward or behind this point will display an unevenly loaded surface area.

Forward of the mid-foot, the load distribution will skew forward, reducing the surface area of force distribution - likewise if the bar is behind the balance position.

Physics Class

The most important effect of this uneven loading is that it sets up uneven moment forces between the balance point and the lifter/barbell Center of Mass measured vertically from the floor.

Moment force, or leverage, is the turning force your hand transmits to a bolt through a wrench. If we measured the force of the spin along the shaft of the bolt, that quantity would be torque, but we aren't concerned with torque since nothing in a human joint spins under normal circumstances.

We're merely concerned with the force transmitted along the shank, thigh, and trunk segments between the barbell and the floor - the force that moves the load.

A wrench multiplies the force you can generate with your hand by trading a longer arc of motion at a higher velocity for a much shorter arc and a higher amount of force. A crowbar works the same way, distance and velocity exchanged for force - mechanical advantage.

The moment arm is the distance between the point of force application (your hand on the crowbar) and the point of rotation (the bend in the short end of the crowbar), measured at 90 degrees to the force application, and it's the way the multiplication of force is calculated.

The longer the moment arm, the greater the leverage at the point of rotation.

A crowbar has a long segment, a bend, and a short segment, and is meant to be used to generate high force when prying a nail out of a board. Here's an example of the same long/short segment configuration used the opposite way:

The trebuchet is a siege engine that uses a very high amount of force on the short segment to increase the velocity of the light load on the end of the long segment.

In this system, the multiplication takes place in the opposite way: like stepping on a rake, high force operating the short segment rotating around a fulcrum produces a high velocity at the end of the long segment, if the force is high enough on the short end.

The angular velocity on both sides of the fulcrum is the same, and the long moment arm multiplies the velocity along the arc at the end of the long segment.

Now, think of the horizontal distance between the mid-foot and the 600-pound bar as a lever against your feet, with the vertical distance up the legs as the segment. If the bar is above the knees and you shift forward 2 inches, the distribution of the weight against the floor shifts forward.

Along the vertical distance between the floor and the barbell, leverage is being applied to the system that wouldn't be there if the bar was directly vertical to the mid-foot.

The horizontal distance between your hips and the bar constitute a moment arm, one that you use to generate enough force to pull the bar up. The additional 2 inches of moment arm your technical mistake has created gives the load on the bar some additional leverage against you.

The total amount of moment force that must be generated is optimal when the bar is over mid-foot, but now the force of the additional 2 inches must be added to the amount of force you have to produce to keep the 600 pounds moving up.

Moving the bar back behind the mid-foot to shorten this moment arm doesn't work, because you're off-balance backwards against the floor, and because moving the hips back lowers them in relation to the knees.

Since the bar moved forward, the countering force that must be added to the pull comes from behind.

At the bottom of the pull, the posterior tug comes from your calf muscles - the gastrocs and soleus. You can feel this effect for yourself if you stand up straight and let your bodyweight drift onto your toes.

It's easy enough to counter this off-balance shift without a 600-pound bar to deal with, but adding enough backward pull from a bar position above the knee can't really be done, since calves aren't designed or positioned to generate force against a barbell above the knee.

Those of us who have ruptured an Achilles tendon know how this works with a load on our backs or on the floor in front of us - the effect is subtle, until you can't produce it effectively, and then you miss a rep or fall forward.

If you start with the bar forward of the balance point, it will roll back to the mid-foot before it leaves the ground, thus correcting the problem while the vertical distance between the bar and the foot is manageably short.

If the weight is light enough, as with a clean, the bar can be pulled off the ground in this forward position, but it will be pulled back toward the balance point as it rises, thus creating a curve in the bar path off the floor.

If it's light enough to pull very inefficiently, as with a snatch, a strong lifter can throw it all over the room and still catch it overhead - not efficient, but quite commonly performed.

If you get forward higher in the pull, the way you might try to save the lift is by making your back angle more vertical earlier in the pull than you would if the bar was in balance - you look up, and you lean back, or at least try to lean back.

This doesn't work very well, as some of the recreational federations have admitted by placing a spotter behind their less-than-technically-competent deadlifters at their meets.

Why the Shoulders Forward of the Bar?

This is a very interesting phenomenon, because it doesn't seem logical that the arms would not just hang straight down when loaded, like a plumb line mirroring the gravity vector.

The point of rotation is the shoulder, the barbell is in the hand, the arm connects the two points, and the damn thing ought to behave properly.

But it doesn't.

Every heavy deadlift hangs from the shoulders with the arms at a slight angle, perhaps 7 to maybe 11 degrees, with the shoulders just forward of the bar, and with the bar over the middle of the foot.

The back angle adjusts to place the shoulders in this position; if the hips are too low, with the shoulders back behind the bar, the back angle will adjust horizontally to place the shoulders in the Standard Pulling Position.

Furthermore, the following generalization is born out by repeated observation: the heavier the pull, the more likely it is to conform to this alignment, and the lighter it is the greater the amount of deviation it's likely to display.

Watch Brad Gillingham's 881/400kg deadlift. Brad comes to the bar and carefully places his mid-foot directly under the bar - shins about an inch from the bar - takes his grip without moving the bar, drops his knees forward until shins touch the bar, squeezes his chest up, and pulls the bar in a vertical line to lockout.

His back angle at the very start of the pull doesn't change to more horizontal, and in fact immediately becomes more vertical as the bar is pulled up.

Notice the shoulders just forward of the bar (ignore the black shirt, look at his shoulders and hands), and notice that the arms don't become vertical until just before lockout.

Perfect pulling efficiency is displayed with the bar over the mid-foot and the shoulders just in front of the bar, the heavier the weight the more efficient the pull must be. You can watch videos for hours on end that show this pattern.

Warm-ups can be done "wrong," as can rows, cleans, snatches, and anything else with a light weight. But when the last bits of your limit capacity are approached, this alignment must be displayed or you miss the pull.

Look at this heavy set of 745x4 by Mike Tuchscherer:

When the bar is forward of the mid-foot during the reps of this set, it drifts back during the pull, but notice the position of the shoulders over the bar, evidenced by the arm angle.

Mike is strong enough to pull this weight with a little horizontal slop in the floor pull, and he does this with heavy attempts as well. But the bar always drifts back to the mid-foot.

More importantly, why are his shoulders in this persistent forward position? This is best explained with an illustration.

Moment force - leverage, like your hand generates when it pulls on a wrench - is most efficiently applied at 90 degrees to the tool being pulled on, be it a wrench, a crowbar, or a hammer.

The latissimus dorsi muscles attach the lower back to the upper arm; specifically, the lats originate on the back from T8 all the way down to the sacrum and across the top of the pelvis, and have an insertion point on the medial anterior proximal humerus, essentially in your armpit.

The shoulders just in front of the barbell place the lats in the best position to apply moment force to the humerus - to best pull the bar back to keep it over the mid-foot balance point.

The lats at 90 degrees is the alignment generated by the shoulders-in-front-of-the-bar position with the arms hanging at an angle, as the figure shows.

You can see the effect of this position quite clearly: control of the tendency of the bar to drift forward is best accomplished with the backward tug provided by the lats.

And the back angle - the angle between the plane of the trunk and the horizontal floor - is what controls the position of the shoulders relative to the bar, and thus the angle of attack between the lats and the humerus.

The actual back angle that occurs in a properly positioned pull is dependent on anthropometry.

A short back and long legs will obviously generate a more horizontal back angle in the proper position than a long back and short legs. In either case, the proper position for the lats against the humerus will result from a shoulder position just in front of the bar that hangs the arms at 7-11 degrees, any variation being due to anthropometry.

Related:  The Belt and the Deadlift

But the lats generate tension between both origin and insertion, so they're pulling on the lower back as well.

Part of the back angle settling into position with shoulders forward of the bar is probably a function of the hips being pulled up into that position by the lat's anterior tension on the low back, as the muscle belly settles into its optimum force production length in isometric contraction.

This effect also rotates the mass of your body up into a position more above the bar. As your own mass moves into a position so that more of it is forward of the bar, the center of mass of your body lines up better with the center of mass of the barbell.

Pulling it upward is then easier, since you obviously can't pull upward on something in front of you. A deadlift will always be in front of your legs, and that's why you lock it out with a slight backward lean - to balance your mass back against the bar in front.

But during the pull, some of your mass - including your head, if your neck is positioned correctly - remains forward of the bar, and the arms don't become completely vertical until you finish the pull.

As for the minutia of the system, the teres major and the long head of the triceps also cross the shoulder joint between the scapula and the humerus, and therefore they're also involved in this moment force relationship.

But the triceps long head is at a very poor angle for generating moment force across this gap, and the teres is a short small muscle; neither are terribly important to the consideration of the larger mechanism at work.

The lats hold the bar back over the mid-foot, and they hold the back angle in a position to keep your mass more over the bar.

Two other back angle configurations are possible.

This is the most common start position in competitive powerlifting, and it's inefficient for reasons that are obvious in light of this analysis.

The most compelling argument against it is the fact that everyone who starts a heavy deadlift here exhibits a shift in back angle towards the Standard Pulling Position.

You can try to pull the bar with vertical arms and hips down too low - "squat with the bar in your hands" - but it just doesn't work that way.

The fact that the extraneous movement occurs before the bar leaves the floor, and that it can be pulled without this extraneous movement demonstrates that a higher-hips position is a more efficient place to start a deadlift.

Watch Ed Coan:

Note that the greatest lifter in the history of the sport of powerlifting demonstrates this shift in back angle.

The pull starts when the bar actually leaves the floor, and during the time between when his upward motion started and the bar leaving the floor his back angle changed.

In fact, there's a slight pause in the motion as the system comes into stability, just before the bar leaves the floor, as the lats "grab" the bar. This is a very common start technique, and there are countless examples of it, to the extent that it's considered by some to be the best way to pull.

If the hips are low, the lats are not optimally engaged with the arms, and the lower back isn't optimally anchored to the bar - the lat generates tension against both the origin and the insertion.

As the lat becomes optimally aligned to hold the bar back over the mid-foot, it also pulls the hips up into their characteristic position, and the resulting back angle is stable just as the bar leaves the floor.

Again, the actual angle depends on anthropometry, but the alignment itself produces the back angle.

This is the other back angle with which the bar can be pulled:

In this position, the lat's angle of attack has opened beyond 90 degrees. This is recognizable as the classic stiff-legged deadlift position, with knees extended and back angle more horizontal.

Those of us (who even lift) know that you can't pull as much in this position as you can with an optimal back angle, and that if you start here you'll almost certainly miss the attempt unless you can lower the hips and pull the bar back in.

The ability to stabilize the bar over the balance point is critical to the ability to apply enough force to pull the deadlift. But there is another reason...

What About The Hamstrings?

Look at the three positions in Figures 9, 10, and 12, and notice the hamstrings.

The hamstrings are really a poorly understood component of the squat and the deadlift, the subject of much unnecessary stretching and "mobility wodding."

Remember the basic rule of hamstring kinematics in the pull and the squat, (and most everything else too): As the hips flex, the knees flex.

If the angle of hip flexion remains roughly equal to the angle of knee flexion, the hamstrings haven't changed muscle belly length very much. Thus, hamstring flexibility isn't the determining factor in squat depth.

If the hamstrings don't change length - this is very hard to measure, and is why it hasn't been done quantitatively - hamstrings function primarily as isometric stabilizers of the back angle in both the squat and the pull.

In both movements, their primary contribution to the kinetic chain is support of the back angle. They anchor the ischial tuberosity to the medial and lateral attachments on the tibia, at the knee.

This pelvis-to-knee connection functions as a bridge between the extending knees and the extending hips, enabling the force generated by the quads, glutes, and adductors to move the load without the back angle collapsing horizontal.

Along with the spinal erectors and the lats, the hamstrings are the "isometric glue" that holds the pull together.

This, coupled with the fact that a muscle generates its greatest contractile force isometrically, at its resting length, means that whatever position generates the best semblance of resting muscle belly length will be the strongest position to use the hamstrings isometrically.

Our analysis shows that in a squat, the low-bar position holds the hamstrings at resting length (or possibly slightly stretched, depending on the lifter's anthropometry) throughout the movement.

In a high-bar squat or front squat, the knee angle is more closed and the hip angle is more open, shortening the hamstrings from their resting length and therefore diminishing their isometric capacity to anchor the back angle.

In a deadlift, the correct start position finds the hip angle more closed and the knee angle more open than in the low-bar squat bottom position, with the hamstrings stretched slightly beyond their resting length, allowing them to contribute primarily isometrically as they hold the back angle in place, as well as contributing to hip extension at the top of the pull as they return to their resting length.

The position which generates the most mechanically-efficient angle of attack on the tibia and the pelvis will be the position that can generate the greatest back angle stability during the first part of the pull.

Look at these three positions and decide for yourself which works best for hamstring function.

What About The Back Angle?

As the bar travels up the shins in a deadlift, the back angle becomes more vertical. This begins immediately after the bar leaves the floor.

In a clean or a snatch - sub-maximal accelerated pulls by definition - the back angle should (and usually does) stay more constant and more horizontal until the bar gets much higher. "Staying out over the bar" is a familiar concept to some Olympic lifters, their having heard the cue many times.

What does it mean, and why?

The concept of the moment arm is quite important throughout barbell training, and nowhere more important than when considering the role of the back in the clean and snatch versus the deadlift.

The primary difference between the Olympic lifts and the deadlift is acceleration - the first derivative of velocity, the rate at which velocity increases.

A clean is a pull that's accelerated enough to catch on the shoulders.

In order to impart sufficient momentum to the loaded barbell that it continues on upward between the end of the pull and the catch on the shoulders - that portion of the bar path during which no force is transmitted to the bar by reacting against the ground - it must be sufficiently accelerated so that it "floats" long enough to shift the feet and the arms into the catch position from the pulling position.

The snatch is caught overhead, and is thus a longer pull with an obviously lighter weight.

As such, there are no slow cleans or snatches. They must be accelerated or they don't rack, and this is why they're better measures of power than "dynamic effort" deadlifts. How precisely do you "miss" a dynamic-effort deadlift?

In stark contrast to a clean, a deadlift can be slow. Some world records have taken 8 seconds to pull, as opposed to less than a second for a clean or snatch.

This critical distinction is the reason for the difference in the behavior of the back angle between the fast and slow pulls: a deadlift shows a back angle that becomes more vertical as it leaves the floor, while a clean and especially a snatch preserve the horizontality of the back angle as long as possible.

Dimas was the undisputed master of staying out over the bar, preserving his back angle until the bar was above his knees.

Note the differences in the spinal position of these two lifters. The difference is acceleration.

This is important because of acceleration, and the way it's produced in a fast pull. A clean is a pull in which the back angle/hip moment arm can be maintained long enough to accelerate the barbell - to increase the linear velocity of the barbell by using the mechanical advantage of the longer moment arm.

The back segment between the hip and the barbell is the "tool" the lifter uses to accelerate the bar. Look at this leverage arrangement:

Like the trebuchet, the clean uses the short moment arm loaded to a high force level and operating over a short arc around the fulcrum to accelerate a much longer moment arm with a lighter load on the end - if you're strong enough.

If the weight is too heavy, this long moment arm can't be maintained; the back angle becomes more vertical immediately because the longer moment arm can't be operated by the posterior chain musculature, the weight therefore can't be accelerated, and it's a deadlift instead of a clean.

And this is why a deadlift can be done with some spinal flexion, and a clean is much more dependent on lumbar and thoracic extension.

Many heavy deadlifts have been pulled with a round upper back, but Olympic lifters who fail to keep their backs tight and flat will have problems reproducing their technique accurately - a rounding back is a power leak, and the deadlift doesn't rely on power and acceleration like the Olympic lifts do.

The Other Details

Sometimes, but not very often, the fine anatomical details of origin/insertion/action of the individual muscles are critical, so forget all that shit I said about this earlier.

Here are a couple of examples where the details about things that can't be analyzed as a rigid-body problem are important.

Eyeballs

Eye gaze direction is critical in all barbell exercises, and is the most commonly misunderstood aspect of squatting and deadlifting.

The chest follows the eyes, and the back angle is the chest. It's very important to understand the role of the trunk segment in the mechanical execution of these two lifts in particular, and how the eye gaze direction can affect the physics of the lifts.

Since this is a deadlift article, we'll stay with pulling. If you look up, the vast majority of you will have overextended your cervical spine - your neck.

This seems probably counterproductive, considering the fact that the spine is best loaded in normal anatomical position, the way it's best configured to transmit force between the vertebral bodies spaced apart with intervertebral discs, who like to be loaded in compression the way they're designed to transmit force.

Your head actually weighs 5-8% of your bodyweight, and keeping your neck in normal extension maintains the position of more of your body's mass in front of the bar. It actually produces a longer back segment, some of which is then positioned forward of the bar.

We've already observed that you can't pick up a heavy object that's too far "in front" of you, and that more of your mass forward of the bar balances the alignment of the bar's center of mass and that of your body.

Keeping your head in line with your back maintains this mass relationship much better than an overextended cervical spine. This effect is obviously more important in a lighter pull, like a clean or a snatch.

Now, observe the anatomy of the traps. Note that it has an origin from the base of the skull all the way down to T12, thus making it the longest muscle origin in the human body.

Note that almost all these fibers insert on the spine of the scapula. The traps therefore support the scapula, which articulates with the arm, which holds the bar. The bar therefore hangs from the traps, which hang from the spine, from the base of your skull down to the last vertebra with a rib attached to it.

And you want to lift a heavy weight with the top one-third of your spine in overextension, with your neck curved like a hook? You should probably rethink this decision.

We've already explored the role of the back angle, so do an experiment. Stand up straight and look at the floor about 15 feet in front of you. Note your posture and the weight distribution on your feet against the floor.

Now, look up at the ceiling, the way your high-school football coach told you. "Look up, son! You gotta look up if you wanna go up! I said look up, boy! Look up through the top of your skull!"

Our experience with this little test indicates that about 80% of you will feel your weight go to your toes. This is because your chest follows your eyes, and your back angle follows your chest, and you lean onto your toes to compensate so you don't fall backwards.

If this happens at the bottom of the pull (or the squat) when your knees and hips are in flexion, the result will be that the hips move forward a little, since "the back bone's connected to the hip bone."

And since "the hip bone's connected to the knee bone," the knees will move forward a little too. This closes the knee angle and distally slacks the hamstrings, which you're trying to use to support the moment arm on the hips.

If you have trouble in the middle of a pull, check your eye gaze direction and see if you're looking up. If so, try fixing your gaze on a point on the floor that holds your chest in the best position to use your back angle for the pull.

Grip

You've probably been taught to use an alternate grip when you deadlift. This position places one hand supine and the other hand prone on the bar, and is a very secure grip for a heavy single.

It also places one shoulder in internal rotation and the other in external rotation. Most competitors use an alternate grip in a meet. But not all of them - look closer at Gillingham's 881 above.

And not every pull is a limit deadlift. There are consequences to the use of asymmetric shoulder loading in a pull, and some attention should be paid to this when you decide which grip to use.

Focus now, just one more time: Remember that the lat attaches in the armpit, to the proximal medial anterior humerus, in front and on the inside of the bone.

When you assume a supine grip and externally rotate the humerus, you're altering the tension on the lat by increasing its length relative to a prone grip in internal rotation. You're also creating a wonderful opportunity to add bicep tension - and therefore elbow asymmetry - since the bicep is the primary elbow supinator.

This asymmetric lat tension could have significant consequences in the start position of the pull, because of the resulting asymmetric tension on both the origin and insertion - the low back and the upper arm. Many people rotate away from the supine side during a deadlift.

How many low back tweaks have resulted from an alternate grip? I don't know, more that 8 or 10, but it's something to think about when you decide between an alternate grip and a hook grip.

In Short...

Just improve your deadlifts, and think a little more clearly when you come to the bar.

Note: Illustrations are the copyright of the The Aasgaard Company.