Table of Contents
Introduction ................................................................................................................... 4
Advanced Models .............................................................................................................................................. 4
Assumptions/Limitations ............................................................................................................................. 4
Moment Arms ................................................................................................................ 5
Support Moment ........................................................................................................... 6
Force Sharing ................................................................................................................. 8
Barbell Squat Torques ................................................................................................ 9
Knee Dominant Squat .................................................................................................................................. 10
Hip Dominant Squat ..................................................................................................................................... 11
Barbell Deadlift Torques ......................................................................................... 12
Knee Dominant Deadlift .............................................................................................................................. 12
ROM and Torque ......................................................................................................... 13
Passive-Elastic and Active Muscle Force ............................................................ 14
Sticking Regions.......................................................................................................... 15
Long Femurs in the Squat ........................................................................................................................... 16
The Effect of Femur Length on Maximum Squat Strength............................................................. 17
Long Arms in the Deadlift ........................................................................................................................... 18
Gluteus Maximus EMG and Hip Extension Torque-Angle Curves .............. 20
Effect of Gluteus Maximus Hypertrophy on Maximum Hip Extension
Torque............................................................................................................................ 21
Spinal Rounding.......................................................................................................... 23
Spinal Rounding Torques ........................................................................................................................... 23
Spinal Rounding in the Deadlift ............................................................................................................... 23
Spinal Rounding and Spinal Loading ..................................................................................................... 24
Spinal Rounding and Deadlift Muscle Activation .............................................................................. 24
Biomechanics of the Lumbopelvic Hip Complex.............................................. 25
Counterbalance Squat and Torques..................................................................... 26
Trunk Position in the Squat .................................................................................... 27
High Bar vs Low Bar Squats .................................................................................... 28
Squat Variations ......................................................................................................... 29
Front Squat....................................................................................................................................................... 29
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Back Squat ........................................................................................................................................................ 29
Box Squat .......................................................................................................................................................... 29
Zercher Squat .................................................................................................................................................. 29
Deadlift Variations ..................................................................................................... 31
Conventional Deadlift .................................................................................................................................. 31
Sumo Deadlift .................................................................................................................................................. 31
Trap Bar Deadlift ........................................................................................................................................... 31
Hack Lift ............................................................................................................................................................ 31
Common “Dysfunctions” .......................................................................................... 33
Knee Valgus ...................................................................................................................................................... 33
Butt Wink .......................................................................................................................................................... 33
Poor Ankle Mobility ...................................................................................................................................... 33
Poor Core Stability ........................................................................................................................................ 34
Dorsiflexion Aids in the Squat ............................................................................... 35
Belts and Intra-Abdominal Pressure ................................................................... 36
Knee Wraps, Suits, Briefs, and Torque................................................................ 37
Theoretical Effects of Support Gear........................................................................................................ 38
Bands, Chains, and Torque ......................................................................................................................... 39
Assistance Lifts ............................................................................................................................................... 40
Hip Thrust......................................................................................................................................................... 41
Back Extension on GHD ............................................................................................................................... 41
45º Hyper.......................................................................................................................................................... 41
Good Morning.................................................................................................................................................. 42
Reverse Hyper................................................................................................................................................. 42
Glute Ham Raise ............................................................................................................................................. 43
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Introduction
The word “biomechanics” stems from the Greek language for “life mechanics,” but this
doesn’t really tell us much; Oxford tells us a bit more, “the study of the mechanical laws
relating to the movement or structure of living organisms.” Biomechanics can refer to a
number of subconcentrations, such as fluid dynamics or tissue modeling, but perhaps the
most relevant to strength & conditioning is musculoskeletal biomechanics.
Musculoskeletal biomechanics is a subconcentration of biomechanics in which the
mechanical laws of physics are applied to the human musculoskeletal system. When one
performs a closed chain kinetic movement, their body can be viewed as a system of levers
so that the torque on each joint can be calculated. The torque on a joint is indicative of how
much turning force is being placed on that joint, which can enable us to estimate how hard
a muscle (or group of muscles) has to work to overcome that torque in order to move or
prevent the movement of a joint about its axis. Another term for torque is moment.
Throughout this text, the biomechanics of the squat, deadlift, and their variations will be
discussed, paying particular attention to the effects of technique and form on joint torques.
Advanced Models
In an ideal world, we would use techniques such as muscle modeling, which requires threedimensional motion capture, electromyography, force plates, and specialized software to
help us calculate precise and individualized biomechanical evaluations. Unfortunately, this
equipment costs hundreds of thousands of dollars and is only used in extensive
biomechanics laboratories. However, this does not mean that biomechanical principles
cannot be applied using the naked eye.
Assumptions/Limitations
Throughout this text, certain assumptions are made, as we do not have access to the
advanced modalities previously described. Assumptions and limitations within this text
are as follows:
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•
•
•
•
•
•
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•
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•
•
Assuming that the lifter pushes through the center of the foot
Assuming that the center of gravity is positioned near the load itself in the barbell
squat and through the scapula for the barbell deadlift
Ignoring muscle co-contractions
Ignoring electromyography (EMG)
Focusing on external load, not system mass (ignoring superincumbent bodyweight)
Not using video capture and force plates
Not using inverse dynamics or 3D modeling
Focusing only on vertical forces during the squat and deadlift
Ignoring momentum, looking at instantaneous torques using quasi-static models
Assuming that the plate radius is 22.5cm
Omitting hand length with regards to grip in the deadlift
Assuming a high bar squat position
Assuming that the spine stays rigid and no pelvic tilt exists
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Page 4
Moment Arms
In physics, a moment arm is simply the perpendicular distance from the axis of rotation to
the line of action of the force. In biomechanics, there are two types of moment arms that
you should be familiar with. There’s the muscle moment arm, which is internal and
represents the leverage of a muscle (perpendicular distance between the joint center and
muscle line of pull), and there’s the resistance moment arm, which is external and
represents the perpendicular distance between the load and the joint center. This text will
focus on resistance moment arms.
With squats, the moment arm (sometimes called lever arm) can be estimated by examining
the horizontal distance between the joint center and the ground reaction force vector.
With heavy loads, we can assume that the horizontal component of the ground reaction
force vector is negligible. Therefore, the ground reaction force vector is perpendicular to
the ground and is formed by drawing a line that connects the center of gravity and center of
pressure through the feet, as depicted to the left.
A compound movement consists of moving multiple levers about
multiple joints in order to complete a movement. For example,
during the deadlift, knee extension and hip extension occur
simultaneously. This is drastically different from isolation
movements such as the preacher curl whereby elbow flexion is
the only joint action occurring. During the preacher curl, the
humerus (upper arm) is in a fixed position such that the forearm
must rotate about a fixed axis, and thus not leaving much room to
modify the movement. Compound movements have more
degrees of freedom, or more ways to complete the movement,
consequently making compound movements more complicated,
harder to analyze, and more unique from person-to-person.
Moment arms of the knee
and hip during a squat.
2 x 4: Maximum Strength
Movement variation between individuals is not necessarily a bad
thing, but it can help identify strengths and weaknesses during
movement by calculating joint torques and seeing how different
lifters “favor” different joints.
This manual uses computer-aided design (CAD) drawings drawn
to scale in order to depict the changing moment arms and
subsequent changing joint torques associated with lower body
exercise, paying particular attention to the barbell squat and
deadlift.
Page 5
Support Moment
Using the moment arm and load being used (along with the superincumbent bodyweight,
or mass of the bodyweight above the joint being examined in standing exercises), torques
can be calculated. Torque (τ) is the product of the force and moment arm, as described in
the equation below where r is the length of the moment arm in meters and F is the force in
Newtons.
𝝉𝝉 = 𝑭𝑭 ∗ 𝒓𝒓
In biomechanics, torque is calculated using Newton meters (Nm). Newtons are the SI unit
of force. Because gravity on Earth is constant, we can use 9.8 m/s2 for a (we’ll round up to
10 for the sake of simplicity in this manual), and simply substitute the mass of the load in
kilograms for m (we’ll use 100 kg throughout this text). The equation below will calculate
the force in Newtons using the units described.
𝑭𝑭 = 𝒎𝒎 ∗ 𝒂𝒂
When calculating torque, the force will be constant and the length of the moment arm will
determine differences in torque. With explosive lifts, you’d need to deal with momentum,
but with heavy lifts, this momentum can be ignored, as quasi-static models with lifts taking
more than 2-seconds have been shown to be 99% as accurate as dynamic models (Lander
et al., 1990). Variations in form and lever length will show that a movement can be
completed using an infinite number of torque and moment variations.
In many activities, it is surprising to find that the body tends to distribute a fairly consistent
total amount of joint torque independent of the movement style between the three primary
lower body joints. For example, let’s say that 200 Nm of lower body extensor torque is
required to lift a box. The body could move mostly at the hips and utilize 150 Nm of hip
extension torque and 25 Nm of ankle plantar flexion and knee extension torque to achieve
the task. It could also produce 120 Nm of knee extension torque, 50 Nm of hip extension
torque, and 30 Nm of plantar flexion torque. The take-away point here is that there are
many movement patterns that can lead to successful lifting outcomes, and the various
lifting styles tend to require similar total extensor torques but with different distributions
across the various joints.
See the three pictures below representing a lifter picking up a 20-kg box with a kneedominant style, a blended style, and a hip-dominant style; the combined hip and knee
moments of the three variations is 84.36 Nm, 84.54 Nm, and 82.56 Nm, respectively.
In this manual, 𝝉𝝉𝑯𝑯 will stand for hip extension torque, while 𝝉𝝉𝑲𝑲 will stand for knee
extension torque.
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Page 6
Examples
𝑭𝑭 = 𝒎𝒎 ∗ 𝒂𝒂
𝑭𝑭 = 20 𝑘𝑘𝑘𝑘 ∗ 10 𝑚𝑚�𝑠𝑠 2
𝑭𝑭 = 200 𝑁𝑁
𝝉𝝉𝑯𝑯 = 200 𝑁𝑁 ∗ 0.1535 𝑚𝑚
𝝉𝝉𝑯𝑯 = 30.7 𝑁𝑁𝑁𝑁
𝝉𝝉𝑯𝑯 = 200 𝑁𝑁 ∗ 0.3097 𝑚𝑚
𝝉𝝉𝑯𝑯 = 61.94 𝑁𝑁𝑁𝑁
𝝉𝝉𝑯𝑯 = 200 𝑁𝑁 ∗ 0.4571 𝑚𝑚
𝝉𝝉𝑯𝑯 = 91.42 𝑁𝑁𝑁𝑁
𝝉𝝉 = 30.7 𝑁𝑁𝑁𝑁 + 53.66 𝑁𝑁𝑁𝑁
𝝉𝝉 = 84.36 𝑁𝑁𝑁𝑁
𝝉𝝉 = 61.94 𝑁𝑁𝑁𝑁 + 22.58 𝑁𝑁𝑁𝑁
𝝉𝝉 = 84.54 𝑁𝑁𝑁𝑁
𝝉𝝉 = 91.42 𝑁𝑁𝑁𝑁 − 7.78 𝑁𝑁𝑁𝑁
𝝉𝝉 = 82.56 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 200 𝑁𝑁 ∗ 0.2683 𝑚𝑚
𝝉𝝉𝑲𝑲 = 53.66 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 200 𝑁𝑁 ∗ 0.1129 𝑚𝑚
𝝉𝝉𝑲𝑲 = 22.58 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 200 𝑁𝑁 ∗ 0.0389 𝑚𝑚
𝝉𝝉𝑲𝑲 = 7.78 𝑁𝑁𝑁𝑁
Lander, J. E., Simonton, R. L., & Giacobbe, J. K. (1990). The effectiveness of weight-belts
during the squat exercise. Medicine and science in sports and exercise, 22(1), 117-126.
2 x 4: Maximum Strength
Page 7
Force Sharing
It is not uncommon for more than one muscle to be able to control for the same joint action,
illustrated by the actions of the gluteus maximus and hamstrings on hip extension. How
much each muscle contributes to a joint action depends on a number of factors, including
the joint angle and the strength of each muscle, but these factors are not universal. For
example, the prime mover of the hip thrust is the gluteus maximus, but the hamstrings
contribute to hip extension as well, so hip extension forces are not mutually exclusive to
one muscle. The contribution of a muscle to a movement on a joint is not the same in every
person, thus exercises must be chosen in accordance to how that individual can activate the
intended target musculature.
Studies show that with cueing and focus of attention, one can change the amount of EMG
activity in the various synergists during a movement involving multiple muscles (Lewis &
Sahrman, 2009). For example, using more glutes during hip extension will cause a
decrease in hamstring activation. What’s more, this force sharing has been shown to be
easier to do with lighter loads compared to maximal loads (Snyder & Fry, 2012). Although
we can assume that if a movement produces a large magnitude of hip extension torque, it
will be a good movement for the gluteus muscles, we must be careful with our assumptions
as the movement could be carried out largely by the hamstring and adductor muscles.
Lewis, C. L., & Sahrmann, S. A. (2009). Muscle activation and movement patterns during
prone hip extension exercise in women. Journal of athletic training, 44(3), 238.
Snyder, B. J., & Fry, W. R. (2012). Effect of Verbal Instruction on Muscle Activity During the
Bench Press Exercise. The Journal of Strength & Conditioning Research, 26(9), 2394-2400.
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Page 8
Barbell Squat Torques
During the torque calculation of a squat, as seen in the drawing below, we can assume that
the center of the barbell falls in line with the gravitational force vector (the lifter does not
shift the barbell too far forward or backward relative to the midfoot). A line representing
the gravitational force vector should be drawn through the bar and center of pressure of
the feet (assumed to be midfoot), as shown below. This line should be perpendicular to the
ground (we can assume that most of the force is vertical during a squat).
In order to calculate hip and knee torques, lines representing the moment arms should be
drawn perpendicularly from the ground reaction force vector to each of the said joint
centers, as depicted below. Remember, we are ignoring body mass and focusing on barbell
mass. If we wanted to be more accurate, we would look at system mass, which includes
both, however, this allows for simpler calculations.
𝑭𝑭 = 𝒎𝒎 ∗ 𝒂𝒂
𝑭𝑭 = 100 𝑘𝑘𝑘𝑘 ∗ 10 𝑚𝑚�𝑠𝑠 2
𝑭𝑭 = 1000 𝑁𝑁
Because the measurements given are in centimeters,
we will convert them to meters:
1 𝑚𝑚
21.22 𝑐𝑐𝑐𝑐 ∗
= 0.2122 𝑚𝑚 = 𝒓𝒓
100 𝑐𝑐𝑐𝑐
𝝉𝝉 = 𝑭𝑭 ∗ 𝒓𝒓
𝝉𝝉 = 1000 𝑁𝑁 ∗ 0.2122 𝑚𝑚 = 212.2 𝑁𝑁𝑁𝑁
The torque at both the hips and knees is 212.2 Nm.
To the left is the “ideal” squat, that is, the moment
arms are equal to one another to balance out the
torques on the joints. However, this is not a perfect
world and people often do not squat with equal
moments. Powerlifters tend to squat with greater hip
moments while Olympic weightlifters tend to squat
with more equal hip and knee moments. There are
two variations to any squat: a knee dominant and hip
dominant version (actually there’s a continuum with
every possible combination in between).
Learning how to adjust the torques depending on the
task at hand will enable the lifter or coach to make
better decisions in programming and training.
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Page 9
Knee Dominant Squat
Below is a free body diagram representing a lifter that has a knee dominant squat. The
individual’s trunk is more upright which decreases the hip moment and increases the knee
moment. Because the knee moment is now greater, the individual must overcome a greater
knee torque in order to move the weight.
The torques can be calculated as follows:
𝝉𝝉 = 𝑭𝑭 ∗ 𝒓𝒓
𝝉𝝉𝑯𝑯 = 1000 𝑁𝑁 ∗ 0.1414 𝑚𝑚 = 141.4 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 1000 𝑁𝑁 ∗ 0.2829 𝑚𝑚 = 282.9 𝑁𝑁𝑁𝑁
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Page 10
Hip Dominant Squat
A hip-dominant squat is just the opposite of a knee dominant squat, that is, the individual
leans forward and sits back more, which in turn increases the hip moment and decreases
the knee moment. The hips now have more torque to overcome and the knees have less.
Hip-dominant squat torques can be calculated like so:
𝝉𝝉 = 𝑭𝑭 ∗ 𝒓𝒓
𝝉𝝉𝑯𝑯 = 1000 𝑁𝑁 ∗ 0.2829 𝑚𝑚 = 282.9 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 1000 𝑁𝑁 ∗ 0.1414 𝑚𝑚 = 141.4 𝑁𝑁𝑁𝑁
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Page 11
Barbell Deadlift Torques
The torque of a deadlift is calculated similarly to that of the squat, and again, it is safe to
assume that the center of the barbell is the center of gravity, thus, it is where we draw the
gravitational force vector. As one would probably think, the deadlift is a very hip dominant
movement when compared to the squat, as seen below.
𝑭𝑭 = 𝒎𝒎 ∗ 𝒂𝒂
𝑭𝑭 = 100 𝑘𝑘𝑘𝑘 ∗ 10 𝑚𝑚�𝑠𝑠 2
𝑭𝑭 = 1000 𝑁𝑁
Because the measurements given are in
centimeters, we will convert them to meters:
1 𝑚𝑚
45.71 𝑐𝑐𝑐𝑐 ∗
= 0.4571 𝑚𝑚 = 𝒓𝒓
100 𝑐𝑐𝑐𝑐
𝝉𝝉 = 𝑭𝑭 ∗ 𝒓𝒓
𝝉𝝉𝑯𝑯 = 1000 𝑁𝑁 ∗ 0.4571 𝑚𝑚 = 457.1 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 1000 𝑁𝑁 ∗ 0.0389 𝑚𝑚 = −38.9 𝑁𝑁𝑁𝑁
Knee Dominant Deadlift
𝝉𝝉 = 𝑭𝑭 ∗ 𝒓𝒓
𝝉𝝉𝑯𝑯 = 1000 𝑁𝑁 ∗ 0.3879 𝑚𝑚 = 387.9 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 1000 𝑁𝑁 ∗ 0.0290 𝑚𝑚 = 29.0 𝑁𝑁𝑁𝑁
As you can see, the hip and knee dominant deadlifts are
quite different than those of the squat. The top image
actually involves a knee-flexion net moment where the
hamstrings dominate the quadriceps, whereas the
bottom image shows a knee-extension net moment
where the quadriceps dominate the hamstrings.
However, the net torques are only around 70Nm apart.
Any way you slice it, the deadlift is a hip dominant
movement.
2 x 4: Maximum Strength
Page 12
ROM and Torque
Once one has basic knowledge of the workings of torque, it is easy to see how range of
motion affects the torque placed on joints. In the picture below, you’ll see a parallel squat
and a quarter squat. Assume a 100kg load for the parallel squat and 115kg load for the
quarter squat.
𝝉𝝉 = 1000 𝑁𝑁 ∗ 0.2121 𝑚𝑚
𝝉𝝉 = 212.1 𝑁𝑁𝑁𝑁
𝝉𝝉 = 1150.02 𝑁𝑁 ∗ 0.1844 𝑚𝑚
𝝉𝝉 = 212.1 𝑁𝑁𝑁𝑁
As you can probably imagine, similar torques are created with partial movements
compared to full range movements because more load can be utilized. In the above
example, one would need 15% more load to make up for less ROM (right) in order to match
the torques placed on his joints in the deeper squat (left). The full range movements
possess greater moment arms with lower forces, while the partial movements possess
smaller moment arms with greater forces. Since torque equals perpendicular force times
the length of the moment arm, you end up with similar torques. It should be noted,
however, that full range movements tend to produce greater hypertrophic adaptations in
the literature (Bloomquist et al., 2013).
Bloomquist, K., Langberg, H., Karlsen, S., Madsgaard, S., Boesen, M., & Raastad, T. (2013).
Effect of range of motion in heavy load squatting on muscle and tendon
adaptations. European journal of applied physiology, 1-10.
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Page 13
Passive-Elastic and Active Muscle Force
There are two forces that make up total muscle forces: passive-elastic and active. As one
would probably guess, active forces originate from the contracting muscles, but passiveelastic forces are less heard of. A passive-elastic force is simply the force generated from
the elasticity in passive tissue structures, such as tendons and the elastic properties of
muscle. They’re called into play when the structure is stretched and are for the most part
independent of active contraction. However, titin, a large molecule in the sarcomere, elicits
much more passive force when activated and stretched.
2 x 4: Maximum Strength
Page 14
Sticking Regions
Everybody has a weak point, or sticking region, in the squat and deadlift. These become
especially apparent at near-maximal loads and tend to be different for everyone, but why
do these sticking points occur?
Various theories have been presented, but here, we are going to concentrate on two of
those theories. The first being that sticking regions are caused by the lifter running out of
passive forces, for example from titin and other passive tissues, and having to switch over
to purely active, contractile forces. This seems to be the case in the bench press (Elliot et al.,
1989). This is most likely the cause of most sticking regions.
Another theory is that the body acts like a spring, especially in large individuals. Let’s take
the squat, for example. As one descends, their hamstrings will make contact with their
calves and their belly will make contact with their thigh. These tissues pressing against one
another will create contributory passive forces in the bottom of a lift. This is not the case
for every individual and varies greatly between lifters depending on their form, depth, and
size.
Where sticking regions occur seems to differ greatly from individual to individual, but they
are similar between lifts in the same individual. For example, person A will have a similar
sticking region in both the sumo and conventional deadlift, but those sticking regions will
differ from person B’s sticking regions in the sumo and conventional deadlift (McGuigan &
Wilson, 1996).
It should be noted that often the sticking regions in the squat
and the deadlift occur at different joint angles. For the hips,
the sticking points are at 82º and 96º for the squat and
deadlift, respectively. For the knees, the sticking points are
at 101º and 155º for the squat and deadlift, respectively.
These data indicate that one lift does not necessarily carry
over to the other lift, as sticking points are significantly
different from one another (Hales et al., 2009).
Elliott, B. C., Wilson, G. J., & Kerr, G. K. (1989). A biomechanical analysis of the sticking
region in the bench press. Medicine and Science in Sports and Exercise, 21(4), 450.
McGuigan, M. R., & Wilson, B. D. (1996). Biomechanical analysis of the deadlift. The Journal
of Strength & Conditioning Research, 10(4), 250-255.
Hales, M. E., Johnson, B. F., & Johnson, J. T. (2009). Kinematic analysis of the powerlifting
style squat and the conventional deadlift during competition: is there a cross-over effect
between lifts?. The Journal of Strength & Conditioning Research, 23(9), 2574-2580.
2 x 4: Maximum Strength
Page 15
Anthropometry and Torque (Lightning Bolt)
The length of one’s limbs and trunk have a large effect on the torques their bodies must
produce in order to move a load. Every individual possesses an inherent “lightning bolt”
when you consider the anatomical lengths of their torsos, femurs, and tibias. These limb
length proportions determine much of what form looks like in a squat. Technique, muscle
strengthening, and motor control can certainly alter form, but there’s only so much one can
do, especially with extreme proportions.
Long Femurs in the Squat
The Crural Index is the ratio of the length of the lower leg to that of the upper leg. If one
has a low Crural Index, that is, longer femurs, it puts the lifter in a disadvantageous position
during the squat. The next page shows a comparison of a squatter with normal femur
length with a squatter with short femurs and a squatter with long femurs. Taken to an
extreme level, if most of the total “lightning bolt” is taken up by the spine and tibias, the
lifter will stay upright and be much stronger in the squat as a result. Conversely, if most of
the total “lightning bolt” is taken up by the femur, the lifter will fold like an accordion and
be weaker in the squat as a result.
Take world-class 114-pound Polish powerlifter Andrzej Stanaszek, for example. Stanaszek
is a dwarf, meaning he has disproportionately short limbs and is less than 4’10 (he actually
stands under 4’). These proportions give him a mechanical advantage to lift huge loads,
including a 662.5 lb squat and 402.3 lb bench press. Both the bench and squat favor
shorter limbs. Click HERE to see his squat. Ironically, these same proportions don’t appear
to help him in the deadlift - HERE Andrzej fails with 319 lbs.
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Page 16
Below are squats and their moment arms for a normal sized femur, disproportionately long
femur (+20%), and disproportionately short femur (-20%), respectively.
Medium Femurs
𝝉𝝉 = 1000 𝑁𝑁 ∗ 0.2122 𝑚𝑚
𝝉𝝉 = 212.2 𝑁𝑁𝑁𝑁
Long Femurs
𝝉𝝉 = 1000 𝑁𝑁 ∗ 0.2546 𝑚𝑚
𝝉𝝉 = 254.6 𝑁𝑁𝑁𝑁
Short Femurs
𝝉𝝉 = 1000 𝑁𝑁 ∗ 0.1697 𝑚𝑚
𝝉𝝉 = 169.7 𝑁𝑁𝑁𝑁
The resulting knee and hip torques are directly proportional to the increase or decrease in
femur length (20%). As you can imagine, having shorter femurs confers a distinct
advantage in the squat!
The Effect of Femur Length on Maximum Squat Strength
Now, let’s say we have two individuals: one with short femurs and one with long femurs (as
seen above). How does femur length and its effects on torque requirements affect how
much one can lift? Well, let’s find out. Let’s assume each lifter possesses 500Nm of hip
extension torque and 400Nm of knee extension torque at the bottom of the squat, which
would make them highly advanced powerlifters.
2 x 4: Maximum Strength
Page 17
Long Femurs
400 𝑁𝑁𝑁𝑁
𝑭𝑭𝑲𝑲 =
0.2546 𝑚𝑚
𝑭𝑭𝑲𝑲 = 1571.09 𝑁𝑁
500 𝑁𝑁𝑁𝑁
𝑭𝑭𝑯𝑯 =
0.2546 𝑚𝑚
𝑭𝑭𝑯𝑯 = 1963.86 𝑁𝑁
𝜮𝜮𝜮𝜮 = 𝑭𝑭𝑯𝑯 + 𝑭𝑭𝑲𝑲
𝜮𝜮𝜮𝜮 = 1571.09 𝑁𝑁 + 1963.86 𝑁𝑁
𝜮𝜮𝜮𝜮 = 3534.95 𝑁𝑁 = 796.35 lbs
Short Femurs
400 𝑁𝑁𝑁𝑁
𝑭𝑭𝑲𝑲 =
0.1697 𝑚𝑚
𝑭𝑭𝑲𝑲 = 2357.10 𝑁𝑁
500 𝑁𝑁𝑁𝑁
0.1697 𝑚𝑚
𝑭𝑭𝑯𝑯 = 2946.38 𝑁𝑁
𝑭𝑭𝑯𝑯 =
𝜮𝜮𝜮𝜮 = 𝑭𝑭𝑯𝑯 + 𝑭𝑭𝑲𝑲
𝜮𝜮𝜮𝜮 = 2357.10 𝑁𝑁 + 2946.38 𝑁𝑁
𝜮𝜮𝜮𝜮 = 5393.48 𝑁𝑁 = 1,215.04 lbs
According to these estimations, a squatter with 20% shorter femurs with the same amount
of knee and hip extension torques can squat 41.6% more than a squatter with 20% longer
femurs. In fact, reducing femur length transformed the powerlifter from strong to world
record holder!
Long Arms in the Deadlift
Because the starting position of the deadlift is determined by an individual’s arm length, an
individual with longer arms is at a much greater mechanical advantage than an individual
with shorter arms. This is due to the peak torque of a deadlift being at the bottom of the
movement. A more vertical trunk angle can be seen in the diagrams below just adding
length to the arms of the lifter without altering leg and torso lengths.
Lamar Gant is a great example of a phenomenal deadlifter with long arms. At a bodyweight
of 132, Gant was able to pull 683.4 lbs. Click HERE to watch Lamar’s deadlift – notice that
he locks out with the bar resting just above the kneecaps. The free body diagram on the
following page shows why and is drawn similarly to the squats in that the arms were either
shortened or elongated by 20%. The first image is normal length, second is shortened, and
third is elongated.
2 x 4: Maximum Strength
Page 18
Medium Arms
𝝉𝝉 = 1000 𝑁𝑁 ∗ 0.4571 𝑚𝑚
𝝉𝝉 = 457.1 𝑁𝑁𝑁𝑁
Short Arms
𝝉𝝉 = 1000 𝑁𝑁 ∗ 0.4610 𝑚𝑚
𝝉𝝉 = 461.0 𝑁𝑁𝑁𝑁
Long Arms
𝝉𝝉 = 1000 𝑁𝑁 ∗ 0.4326 𝑚𝑚
𝝉𝝉 = 432.6 𝑁𝑁𝑁𝑁
The resulting hip torques are directly proportional to the increase or decrease in arm
length (20%). In addition the joints have to move through a much larger range of motion,
which will lead to greater fatigue throughout the lift. As you can imagine, having longer
arms confers a distinct advantage in the deadlift!
2 x 4: Maximum Strength
Page 19
Gluteus Maximus EMG and Hip Extension
Torque-Angle Curves
Worrell et al. (2001) investigated gluteus maximus EMG and its relation to hip extension
torque, and the findings are puzzling to say the least. Below is a rendition of Figure 6 from
the study.
Subjects performed maximal hip extension torque at four different angles of hip flexion. As
you can see, hamstring EMG does not change very much throughout the hip range of
motion, however, gluteus maximus EMG rises from a flexed to an extended hip position.
Interestingly, hip extension torque is greater in a hip flexed position compared to a hip
extended position. Why this occurs is not fully understood. We are probably stronger in
hip flexion due to the increased involvement of the adductors in hip extension. The glutes
probably fire harder at end range hip extension to compensate for their shorter lengths or
because they have better leverages at that range of motion.
These findings are highly applicable to training as they explain how the muscle works and
provide some insight as to the best way to train the gluteus maximus. If one wants to
optimize the gluteus maximus hypertrophic response, he or she needs to incorporate
multiple hip extension movements such as hip thrusts, squats, and deadlifts.
Worrell, T. W., Karst, G., Adamczyk, D., Moore, R., Stanley, C., Steimel, B., & Steimel, S.
(2001). Influence of joint position on electromyographic and torque generation during
maximal voluntary isometric contractions of the hamstrings and gluteus maximus
muscles. The Journal of orthopaedic and sports physical therapy, 31(12), 730.
2 x 4: Maximum Strength
Page 20
Effect of Gluteus Maximus Hypertrophy on
Maximum Hip Extension Torque
It is well known that when a muscle is hypertrophied, it is also stronger. This is due to the
increase in physiological cross sectional (PCSA). Let’s quickly familiarize ourselves with a
few formulas pertaining to muscle PCSA and its relationship to torque.
𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃 (𝑐𝑐𝑐𝑐2 ) =
𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚 𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣 (𝑐𝑐𝑐𝑐3 )
𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓 𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙ℎ (𝑐𝑐𝑐𝑐)
𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀 𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓 (𝑁𝑁) = 𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃 (𝑐𝑐𝑐𝑐2 ) ∗ 𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡 (𝑁𝑁�𝑐𝑐𝑐𝑐2 )
Specific tension refers to the force exerted by the fibers per unit of PCSA. This would be
measured in N/cm2. Muscle force denotes how much force the muscle pulls with, but as
we know from previous sections in this text, we care about torque.
In order to calculate the muscle moment (torque), we must multiply the muscle force by
the perpendicular distance from the muscle’s line of pull to the joint center. The following
image shows how hypertrophy can affect the muscle’s moment arm and therefore, moment.
2 x 4: Maximum Strength
Page 21
As you can see, as a muscle hypertrophies, it not only gets larger and farther from the joint
center, but the angle of the fibers also change, thus giving it a larger capacity for torque
development. Below is an example of how someone’s hip extension torque would change
as a result of a 31.85% increase in gluteus maximus size.
𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃 = 28.92 𝑐𝑐𝑐𝑐2
𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀 𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓 = 28.92 𝑐𝑐𝑐𝑐2 ∗ 61 𝑁𝑁�𝑐𝑐𝑐𝑐2
𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀 𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓 = 1,764.12 𝑁𝑁
𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃 = 38.13 𝑐𝑐𝑐𝑐2
𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀 𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑒𝑒 = 38.13 𝑐𝑐𝑐𝑐2 ∗ 61 𝑁𝑁�𝑐𝑐𝑐𝑐2
𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀 𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓 = 2,325.93 𝑁𝑁
Muscle Moment
1,687.04 𝑁𝑁 ∗ 0.0469 𝑚𝑚 = 79.12 𝑁𝑁𝑁𝑁
Muscle Moment
2,325.93 𝑁𝑁 ∗ 0.0567 𝑚𝑚 = 131.88 𝑁𝑁𝑁𝑁
Muscle force corrected for angle of insertion
1764.12 𝑁𝑁 ∗ sin 73º = 1,687.04 𝑁𝑁
Muscle force corrected for angle of insertion
2325.93 𝑁𝑁 ∗ sin 90º = 2,325.93 𝑁𝑁
Thus, a gluteus maximus that is 31.85% larger can produce 50% more hip extension torque.
2 x 4: Maximum Strength
Page 22
Spinal Rounding
Some amount of spinal rounding, specifically in the thoracic region, is acceptable when
approaching maximal loads in the deadlift. Some lifters are strongest when maintaining a
good arch, while others are strongest when they round their spines. You want to make sure
the rounding is in the upper back and that lower back (lumbar) rounding is kept to a
minimum when pulling heavy loads. Here is why you may be stronger when rounding the
upper back.
Spinal Rounding Torques
Depicted below is a conventional deadlift for a lifter with a “neutral” spine, and the same
lifter pulling with a rounded spine. By rounding the spine, the individual is able to decrease
the hip moment, which decreases hip torque and in turn makes the load easier to lift.
Straight Back
𝝉𝝉 = 1000 𝑁𝑁 ∗ 0.4571 𝑚𝑚
𝝉𝝉 = 457.1 𝑁𝑁𝑁𝑁
Rounded Back
𝝉𝝉 = 1000 𝑁𝑁 ∗ 0.4337 𝑚𝑚
𝝉𝝉 = 433.7 𝑁𝑁𝑁𝑁
With a 45º arch, the moment arm on this individual shortens by around 5%. A 5% decrease in
torque could mean the difference between finishing a pull and not, especially in competition.
Rounding also places the places the muscles at different starting lengths, especially if the pelvis
changes position. The pelvis modulates hip extensor length, with anterior tilting placing the hip
extensors at longer lengths and posterior tilting placing the hip extensors at shorter lengths. How
this impacts strength is not very clear, but it may depend on the individual.
Spinal Rounding in the Deadlift
There are several other strength benefits to spinal rounding in addition to its effects on
joint torques, including:
2 x 4: Maximum Strength
Page 23
•
•
•
•
Increased Intra-Abdominal Pressure – Provides additional spinal stabilization.
Passive Erector Support – Titin filaments within the thoracic erectors and tendons
will provide resistance to stretch, similar to the way a spring works.
Spinal ligaments, fascia, joints, and discs – When one approaches full flexion, these
are more or less the body’s last chance to support itself. One should not rely on
these structures, but they do provide support if need be.
Support from the rib cage and sternum – According to Watkins IV et al. (2005), the
sternocostal complex has been shown to increase thoracic spine stability during
flexion/extension by 40%.
For more information on the benefits of spinal rounding in the deadlift, check out Bret
Conteras’ article on T-Nation, A Strong Case For The Rounded Back Deadlift.
Watkins IV, R., Watkins III, R., Williams, L., Ahlbrand, S., Garcia, R., Karamanian, A., ... &
Hedman, T. (2005). Stability provided by the sternum and rib cage in the thoracic
spine. Spine, 30(11), 1283-1286.
Spinal Rounding and Spinal Loading
Shearing forces occur when two parts of the body are not aligned which pushes one part of
the body in one direction, and another part of the body in the other direction. This is vastly
different from compression forces, for which intervertebral discs are designed to handle
efficiently. When performing a lift, whether in the gym or in daily life, one should consider
the ramifications of shearing forces on spine health. While the dangers of shear loading
may be grossly exaggerated, spinal rounding undoubtedly places the discs and ligaments
under much greater load. Therefore, spinal rounding should be utilized sparingly, if ever.
Information from: McGill, S. (2007). Low back disorders: evidenced-based prevention and
rehabilitation. Human Kinetics.
Spinal Rounding and Deadlift Muscle Activation
When one rounds his or her spine, the ratio of active to passive forces acting on trunk
extension decreases for the reasons described in the previous sections. In full stretch, the
erectors actually shut off, which is deemed “myoelectric silence.” This means that spinal
erector activation would decrease and, instead, passive tissues would support the spine.
2 x 4: Maximum Strength
Page 24
Biomechanics of the Lumbopelvic Hip
Complex
The lumbar spine, pelvis, and hips make up the lumbopelvic hip complex. Learning how to
properly control and move through this complex can be difficult and daunting, but doing so
will result in a safer, more efficient lift.
One must keep in mind that these structures affect how one’s lumbar spine moves as well,
hence the lumbo in lumbopelvic. For example, if one cannot flex at the hip joint any further,
they will compensate via posterior pelvic tilt and lumbar flexion. During periods of deep
hip flexion, such as the bottom of the squat, it may be beneficial to maintain anterior pelvic
tilt because 1) it will put more tension on the adductors and hamstrings and 2) the glutes
are already inhibited due to deep hip flexion. As for near lockout, such as the top of a
deadlift, the opposite is true: increased posterior pelvic tilt will be a more advantageous
position to produce hip extension torque because the gluteus maximus can better activate
in this position.
Intimately involved in the lumbopelvic hip complex are four different muscles groups: hip
abductors, hip adductors, hip flexors, and hip extensors; one’s structure/anatomy greatly
affects how these function by either increasing or decreasing the moment arm of each
muscle. For example, a 2cm superior displacement of the hip joint center decreases the
moment generating capacity of the hip abductors by 49% and hip flexors by 22%. A hip
center displaced 2cm superiorly, 2cm laterally, and 2cm anteriorly was shown to maximize
hip extension torque (Delp & Maloney, 1993).
Bret does a phenomenal job introducing and further explaining the lumbopelvic hip
complex and these concepts in this video.
Delp, S. L., & Maloney, W. (1993). Effects of hip center location on the moment-generating
capacity of the muscles. Journal of biomechanics, 26(4), 485-499.
2 x 4: Maximum Strength
Page 25
Counterbalance Squat and Torques
The counterbalance squat is a variation of the squat in which weight is held out in front of
one’s body. This will shift the center of mass forward, which will allow a person to sit back
more in order to counteract this shift. The counterbalance is commonly done to help
someone learn the squat or learn pistol squats. The change in moment arms resulting from
this shift in center of gravity increases hip torque and decrease knee torque.
Lynn et al. (2012) looked at the effects of a counterbalance squat vs. regular squats. This
shows the effects of shifting the system center of mass forward on forward trunk lean,
which decreases knee extension torque while increasing hip extension torque.
Goblet Squat
𝝉𝝉𝑯𝑯 = 1000 𝑁𝑁 ∗ 0.1982 𝑚𝑚
𝝉𝝉𝑯𝑯 = 198.2 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 1000 𝑁𝑁 ∗ 0.2261 𝑚𝑚
𝝉𝝉𝑲𝑲 = 226.1 𝑁𝑁𝑁𝑁
Counterbalance Squat
𝝉𝝉𝑯𝑯 = 1000 𝑁𝑁 ∗ 0.3183 𝑚𝑚
𝝉𝝉𝑯𝑯 = 318.3 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 1000 𝑁𝑁 ∗ 0.1060 𝑚𝑚
𝝉𝝉𝑲𝑲 = 106.0 𝑁𝑁𝑁𝑁
Lynn, S. K., & Noffal, G. J. (2012). Lower Extremity Biomechanics During a Regular and
Counterbalanced Squat. The Journal of Strength & Conditioning Research, 26(9), 2417-2425.
2 x 4: Maximum Strength
Page 26
Trunk Position in the Squat
One can change the torques of a squat simply by changing trunk position. When one leans
forward, as seen below, he or she is shifting the torques by decreasing the knee moment
and increasing the hip moment. This is simply another way of sparing the knees, which
may be an individual’s weak link. The opposite is true for someone staying upright, in that
they are sparing their hips (and also lower back) and transferring torque to their knees by
shifting position to increase the knee moment and decrease the hip moment.
Some variables that may also affect trunk position are:
• Dorsiflexion ROM – If one cannot adequately dorsiflex, the knee cannot go forward,
therefore he or she must compensate at the hips by leaning forward more or by
rounding the spine. Otherwise, the lifter would fall backwards.
• Tibia Length – A short tibia means, at the same angle of dorsiflexion, one’s hip
moment arm is greater than that of a person with a longer tibia.
• Femur Length – At the same angle of dorsiflexion, a person with a long femur will
have a greater hip moment arm than a person with a short femur, meaning he or she
will need to lean forward more to keep the center of gravity over the feet.
• Strength Compensation – As noted above, if one has weak knee extensors and
strong hip extensors, it may be beneficial to keep the knee moment small and
compensate by more forward lean. This is often seen mid-lift, i.e., the lifter “runs out”
of knee extension strength/torque, shifts the hips back to increase the hip moment
and decrease the knee moment (which also increases the spinal moment). This shift
in hips also increases hamstring length and allows for greater force output so the
lifter can finish the lift.
Moderate Lean
𝝉𝝉𝑯𝑯 = 1000 𝑁𝑁 ∗ 0.2122 𝑚𝑚
𝝉𝝉𝑯𝑯 = 212.2 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 1000 𝑁𝑁 ∗ 0.2122 𝑚𝑚
𝝉𝝉𝑲𝑲 = 212.2 𝑁𝑁𝑁𝑁
2 x 4: Maximum Strength
Upright Torso
𝝉𝝉𝑯𝑯 = 1000 𝑁𝑁 ∗ 0.1733 𝑚𝑚
𝝉𝝉𝑯𝑯 = 173.3 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 1000 𝑁𝑁 ∗ 0.2510 𝑚𝑚
𝝉𝝉𝑲𝑲 = 251.0 𝑁𝑁𝑁𝑁
Marked Forward Lean
𝝉𝝉𝑯𝑯 = 1000 𝑁𝑁 ∗ 0.2510 𝑚𝑚
𝝉𝝉𝑯𝑯 = 251.0 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 1000 𝑁𝑁 ∗ 0.1733 𝑚𝑚
𝝉𝝉𝑲𝑲 = 173.3 𝑁𝑁𝑁𝑁
Page 27
High Bar vs Low Bar Squats
When one places the bar lower on the back, he or she must compensate by leaning forward
more. This makes low bar squats more hip dominant when compared to high bar, as
shown below. Notice the greater hip extension moments and lesser knee extension
moments in the low bar squat compared to the high bar squat.
High Bar Squat
𝝉𝝉𝑯𝑯 = 1000 𝑁𝑁 ∗ 0.21215 𝑚𝑚
𝝉𝝉𝑯𝑯 = 212.15 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 1000 𝑁𝑁 ∗ 0.21215 𝑚𝑚
𝝉𝝉𝑲𝑲 = 212.15 𝑁𝑁𝑁𝑁
2 x 4: Maximum Strength
Low Bar Squat
𝝉𝝉𝑯𝑯 = 1000 𝑁𝑁 ∗ 0.3012 𝑚𝑚
𝝉𝝉𝑯𝑯 = 311.2 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 1000 𝑁𝑁 ∗ 0.1231 𝑚𝑚
𝝉𝝉𝑲𝑲 = 123.1 𝑁𝑁𝑁𝑁
Page 28
Squat Variations
There are four primary variations of the squat: the front squat, back squat, box squat, and
Zercher squat. Each one of these variations distributes torques differently and those
torque distribution differentiations should be taken advantage of, especially to work on
weak points and during times of injury.
Front Squat
During the front squat, the bar is placed across one’s shoulders and is supported by the
hands. Shifting the bar forward shifts the center of gravity forward, which in turn allows
the lifter to stay more upright. This upright position spares the hips and low back by
placing more torque on the knees, making the front squat a knee dominant movement.
Back Squat
The most popular of the squat variations is the back squat. During the back squat, the bar
is placed on the upper trapezius and the bar is stabilized with the lifter’s hands. This
allows the lifter to go through a more natural range of motion.
Box Squat
Box squats are very similar to back squats, but at the bottom portion, the lifter must sit on a
box. Typically, this movement allows the lifter to keep their shins more vertical as the lifter
leans forward to keep the center of mass over their feet. This alleviates stress on the knees
and makes the movement much more hip dominant than the typical back squat.
Zercher Squat
The Zercher squat is the most unique of the bunch in that instead of the weight resting on
the trunk, it is being held in the lifter’s elbows. This variation is somewhere between the
front squat and back squat in terms of hip and knee joint torques.
Below is a comparison of all four variations.
2 x 4: Maximum Strength
Page 29
Front Squat
𝝉𝝉𝑯𝑯 = 1000 𝑁𝑁 ∗ 0.1766 𝑚𝑚
𝝉𝝉𝑯𝑯 = 176.6 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 1000 𝑁𝑁 ∗ 0.2477 𝑚𝑚
𝝉𝝉𝑲𝑲 = 247.7 𝑁𝑁𝑁𝑁
Box Squat
𝝉𝝉𝑯𝑯 = 1000 𝑁𝑁 ∗ 0.4240 𝑚𝑚
𝝉𝝉𝑯𝑯 = 424.0 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 𝑛𝑛/𝑎𝑎
2 x 4: Maximum Strength
Back Squat
𝝉𝝉𝑯𝑯 = 1000 𝑁𝑁 ∗ 0.2122 𝑚𝑚
𝝉𝝉𝑯𝑯 = 212.2 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 1000 𝑁𝑁 ∗ 0.2122 𝑚𝑚
𝝉𝝉𝑲𝑲 = 212.2 𝑁𝑁𝑁𝑁
Zercher Squat
𝝉𝝉𝑯𝑯 = 1000 𝑁𝑁 ∗ 0.3627 𝑚𝑚
𝝉𝝉𝑯𝑯 = 372.7 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 1000 𝑁𝑁 ∗ 0.0516 𝑚𝑚
𝝉𝝉𝑲𝑲 = 51.6 𝑁𝑁𝑁𝑁
Page 30
Deadlift Variations
Similar to the squat, there are variations of the deadlift that make use of different
combinations of torque in order to complete the lift.
Conventional Deadlift
Obviously the most popular variation of the deadlift, the conventional deadlift, is
performed with the legs in between the arms. This variation is the most hip dominant.
Sumo Deadlift
Powerlifters often utilize the sumo deadlift. By abducting and externally rotating the legs,
they can decrease the hip moment arm and perform the lift in a more upright position since
hip abduction brings their body closer to the bar.
Trap Bar Deadlift
The trap bar deadlift utilizes a trap bar rather than a barbell. This allows the load to be
shifted more posteriorly when compared to the conventional deadlift, and has similar
torque values to that of a squat. Some people refer to this as a squat/deadlift hybrid, or a
squat-lift. This variation is much more knee dominant compared to all other common
variations of the deadlift.
Hack Lift
A hack lift is very similar to a conventional deadlift, except that the bar is behind your legs
instead of in front. This makes the variation much more knee dominant.
Below is a comparison of all four variations.
2 x 4: Maximum Strength
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Conventional Deadlift
𝝉𝝉 = 1000 𝑁𝑁 ∗ 0.4571 𝑚𝑚
𝝉𝝉 = 457.1 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 𝑛𝑛/𝑎𝑎
Hex Bar Deadlift
𝝉𝝉𝑯𝑯 = 1000 𝑁𝑁 ∗ 0.3017 𝑚𝑚
𝝉𝝉𝑯𝑯 = 301.7 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 1000 𝑁𝑁 ∗ 0.1191 𝑚𝑚
𝝉𝝉𝑲𝑲 = 119.1 𝑁𝑁𝑁𝑁
2 x 4: Maximum Strength
Sumo Deadlift
𝝉𝝉 = 1000 𝑁𝑁 ∗ 0.3307 𝑚𝑚
𝝉𝝉 = 330.7 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 𝑛𝑛/𝑎𝑎
Hack Lift
𝝉𝝉𝑯𝑯 = 1000 𝑁𝑁 ∗ 0.2108 𝑚𝑚
𝝉𝝉𝑯𝑯 = 210.8 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 1000 𝑁𝑁 ∗ 0.2096 𝑚𝑚
𝝉𝝉𝑲𝑲 = 209.6 𝑁𝑁𝑁𝑁
Page 32
Common “Dysfunctions”
Knee Valgus
Knee valgus occurs when someone’s knees “collapse” inwards toward one another. This
condition can exist out of movement, and is referred to as genu valgum in those cases, but
during movement, it can often be seen in the concentric portion of a squat or landing from a
jump. Knee valgus is associated with ACL injuries and patellofemoral pain syndrome.
The gluteus medius is a small muscle on the side of your hip that attaches to your illiotibial
(IT) band, which attaches to the lateral aspect of your tibia. This muscle acts to abduct the
hip and, when strengthened, may help prevent knee valgus.
For more on knee valgus, check out Bret’s blog article on it.
Butt Wink
Butt wink occurs when one’s femur runs out of room during hip flexion and makes contact
with the acetabulum. This contact induces posterior pelvic tilt and lumbar flexion, and is
commonly seen in the bottom of a squat.
For more on butt wink, check out Bret’s video on it.
Poor Ankle Mobility
The ability for someone to dorsiflex may affect how they squat, that is, not allowing that
person’s knees to go forward enough which puts an immense amount of torque on their
low back and may cause the person to go into butt wink sooner or have valgus collapse in
order to compensate. Proper ankle dorsiflexion will allow for a more balanced distribution
of torques, and these concepts are also discussed in Bret’s video on butt wink and article on
knee valgus.
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Poor Core Stability
As mentioned earlier, spinal rounding is not just affected by a weak core, it’s affected by hip
and knee strength and is used as a compensatory mechanism. Blaming spinal rounding on
a weak core is a common misconception. Below, one can see how just 15º of spinal
rounding can shift torques in a front squat. If a lifter has weak quads, he or she will be
tempted to round the upper back in the front squat in order to shift more torque to the hips.
However, if one does need to increase their core stability, they can do so by bracing the
abdominals/obliques. This will increase intra-abdominal pressure, which will increase
spinal stability. The downside of this is that it increases spinal compression and your
spinal erectors must produce more torque in order to counteract the spinal flexion
moments provided by your abdominals, and this may lead to greater fatigue.
Front Squat
𝝉𝝉𝑯𝑯 = 1000 𝑁𝑁 ∗ 0.1414 𝑚𝑚
𝝉𝝉𝑯𝑯 = 141.4 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 1000 𝑁𝑁 ∗ 0.2829 𝑚𝑚
𝝉𝝉𝑲𝑲 = 282.9 𝑁𝑁𝑁𝑁
2 x 4: Maximum Strength
Roundback Front Squat
𝝉𝝉𝑯𝑯 = 1000 𝑁𝑁 ∗ 0.21215 𝑚𝑚
𝝉𝝉𝑯𝑯 = 212.15 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 1000 𝑁𝑁 ∗ 0.21215 𝑚𝑚
𝝉𝝉𝑲𝑲 = 212.15 𝑁𝑁𝑁𝑁
Page 34
Dorsiflexion Aids in the Squat
Because dorsiflexion mobility is an issue for many lifters, there are external methods to
help compensate for a small ankle range of motion. These include everything from placing
a plate under someone’s heels to wearing Olympic lifting shoes. These methods, as seen
below, make someone’s starting position in slight plantar flexion, which in turn gives them
a greater range of motion before they reach their true dorsiflexion limit. This concept is
better understood by looking at the free diagrams below, assuming the dorsiflexion aid
puts the lifter in 10º plantar flexion, this dorsiflexion aid can change the moment arms from
a 2:1 to nearly 1:1 ratio, thus balancing out hip and knee torques.
Back Squat
𝝉𝝉𝑯𝑯 = 1000 𝑁𝑁 ∗ 0.2829 𝑚𝑚
𝝉𝝉𝑯𝑯 = 282.9 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 1000 𝑁𝑁 ∗ 0.1414 𝑚𝑚
𝝉𝝉𝑲𝑲 = 141.4 𝑁𝑁𝑁𝑁
2 x 4: Maximum Strength
Back Squat with Oly Shoes
𝝉𝝉𝑯𝑯 = 1000 𝑁𝑁 ∗ 0.2131 𝑚𝑚
𝝉𝝉𝑯𝑯 = 213.1 𝑁𝑁𝑁𝑁
𝝉𝝉𝑲𝑲 = 1000 𝑁𝑁 ∗ 0.2112 𝑚𝑚
𝝉𝝉𝑲𝑲 = 211.2 𝑁𝑁𝑁𝑁
Page 35
Belts and Intra-Abdominal Pressure
As discussed earlier, IAP helps maintain a stable spine, but the addition of a belt will
enhance that effect by creating more intra-abdominal pressure. This is most likely due to
the rigidity of a belt (a bottle) compared to the rigidity of your muscles and connective
tissue (a balloon). Because of the elastic qualities of connective tissue, it will expand like a
balloon with some resistance. A belt, on the other hand, will not give way, thus limiting the
amount of volume in your abdominal cavity. Boyle’s law states that there is an inverse
relationship between volume and pressure, and this explains why a tight belt will increase
IAP.
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Knee Wraps, Suits, Briefs, and Torque
By wearing what is often referred to as “gear” in powerlifting, one can shift their strength
curves, and therefore torque curves to become more even. This works by giving the lifter
assistance where they are weakest but, after that tension from the “gear” is gone, the lifter
must use their own strength to finish the lift. For example, with knee wraps, elastic tension
is added to the knee to help the lifter “spring” out of the hole in a squat. Once the lifter has
taken advantage of this elasticity, he or she must finish the lift with his or her own strength.
In the graph below, the black line represents the standard torque curve and the red line
represents the torque curve with “gear”.
Hip
Exte
nsion
Torq
ue
(Nm)
Hip Angle (º)
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Theoretical Effects of Support Gear
Olympic Shoes
Mainly used for front
squats or Olympic
squats.
Allows lifter to stay
more upright which
decreases spinal
torques and shifts
the demand more to
the knee joint.
A lifter with strong
knees but poor ankle
dorsiflexion rounds
his low back when
he squats. Using
Olympic shoes
enables him to squat
deeper while
keeping his back
upright, leading to
greater forward
knee migration and
knee extension
torque.
Knee Wraps
Mainly used in
geared powerlifting
during squats.
Provides passive
knee extension
torque, especially
during deep knee
flexion.
A lifter can produce
300 Nm of active
knee extension
torque at the bottom
of a squat. With
knee wraps, he may
be able to produce
350 Nm of total
torque.
Briefs/Squat Suit
Mainly used in
geared powerlifting
during squats.
Provides passive hip
extension torque,
especially during
deep hip flexion.
Belt
Mainly used for
squats and deadlifts.
A lifter can produce
400 Nm of active hip
extension torque at
the bottom of a
squat. With a briefs
and a squat suit, he
may be able to
produce 500 Nm of
total torque.
A lifter can produce
200 mmHg of IAP
during the squat
exercise. Wearing a
belt, the lifter can
produce 230 mmHg,
which further
stabilizes the spine.
Enables the lifter to
produce greater
intra-abdominal
pressure during the
squat exercise.
These seemingly minor aids combine to produce large increases in the total poundages that a lifter
can hoist.
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Dynamic Effort and Muscle Activation
Dynamic effort is a method of training popularized by Louie Simmons from Westside
Barbell. Many lifters swear by the dynamic effort method and have noticed marked
strength gains once implementing it. One major benefit of dynamic effort training is that it
is not as taxing on the CNS and can be performed more frequently compared to heavier
lifting. However, one pitfall with dynamic effort is that at the bottom range of motion, you
will accelerate the load, but one must slow down as he approaches the end range of motion
to prevent jarring forces from occurring associated with ballistics. Therefore, muscle
activation decreases to decelerate the bar at end range of motion. To counter this decrease
in muscle activation and increase the acceleration phase of the lift, bands and chains can be
used as accommodating resistance. Even a small amount of accommodating resistance
goes a long way in this regard.
Bands, Chains, and Torque
Bands and chains work similarly to the way powerlifting “gear” works in that they alter the
strength and torque-angle curves, but the way in which they do it works a little bit
differently. Bands and chains are often used to add resistance towards the top of a lift, or
when a lifter is strongest. So, instead of decreasing the resistance in the beginning of a lift
like “gear,” bands and chains increase the resistance toward the end of the lift to help even
out the torque curve. A graph of this can be seen below, where the black line represents a
standard torque curve, and the red line represents the torque with accommodating
resistance.
Hip
Extension
Torque
(Nm)
Hip Angle (º)
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Assistance Lifts
Numerous, non-conventional lifts exist that may help one achieve more success with more
traditional compound lifts. Some important ones will be discussed, along with their
applicability to training and how they are carried over to other lifts.
Muscle Length Compared to Anatomical Position at Peak Hip Extension Torque
Glutes
Hamstrings
Vastis
Squat
Lengthened
Unchanged
Lengthened
Deadlift/Good Morning Lengthened
Lengthened
Slightly Lengthened
Hip Thrust
Unchanged
Shortened
Lengthened
Back Extension
Unchanged
Unchanged
Unchanged
45º Hyper
Slightly Lengthened Slightly Lengthened Unchanged
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Hip Thrust
The hip thrust, popularized by Bret Contreras, is an exercise in which the lifter places their
feet on the ground, upper back on a bench, and bar over their hips, and thrusts the bar
forward. EMG data shows this to be the most constructive exercise for gluteus maximus
activation, which would not only help hypertrophy the glutes, but also strengthen them.
Implications of stronger glutes include a stronger squat if hip extension is a bottleneck and
the lockout in the deadlift. The gluteus maximus has also been shown to be the strongest
stabilizer of the sacroiliac joint (SIJ) (Barker et al., 2013).
The activation patterns of the hip thrust jive very well with the findings of Worrell et al.
(2001), i.e., the gluteus maximus has the highest EMG activity at end range. Because the
force from the load is always perpendicular to the hips, resisting extension, one is able to
maximize hip extension torque and gluteal EMG activity. Below is a graph of the hip
extension torque in a hip thrust of a 6’4, 100kg male using a 220kg load.
Back Extension on GHD
Somewhat of a misnomer, the back extension is really a hip extension exercise. Because the
legs are straight during the back extension, this exercise would elicit more hamstrings and,
because the back is held in a neutral position, the spinal erectors are working isometrically
to stabilize the spine. The gluteus maximus and hamstrings share the hip extension torque.
The movement can be performed on a glute ham developer. The most challenging position
in the back extension is at full lockout where the torso is fully extended.
45º Hyper
The 45º Hyper is a piece of equipment on which the back extension is often performed.
The torques when performing a back extension on the 45º Hyper are on the graph and
show an inverted u-shaped curve, with the most challenging portion in the middle of the lift.
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Good Morning
A good morning is performed similarly to a stiff leg deadlift, but instead of the bar being
held in one’s hands, it is placed on the back – similarly to a back squat. This movement
elicits similar EMG activity as the stiff leg deadlift, that is, hamstrings and glutes
contributing to hip extension and the spinal erectors acting isometrically to maintain a
neutral spine. The torques necessary to complete a good morning are shown on the graph
and show that the most challenging portion is a the bottom of the movement when the hips
are fully flexed.
More information on these concepts, horizontal back extension, 45º hyper, and good mornings are
discussed further by Contreras et al. (2013). Bret was also nice enough to record a video
summarizing the article and these concepts.
Contreras, B. M., Cronin, J. B., Schoenfeld, B. J., Nates, R. J., & Sonmez, G. T. (2013). Are All
Hip Extension Exercises Created Equal?. Strength & Conditioning Journal, 35(2), 17-22.
Reverse Hyper
The reverse hyper was popularized by Louie Simmons at Westside Barbell and is a great
movement for learning how to control one’s pelvis and lumbar spine during a hip hinge
while properly utilizing the glutes. The reverse hyper is performed by laying one’s upper
body face down on a surface with the legs hanging off, secured to a pendulum via a strap.
The lifter will simply move in and out of hip flexion while controlling the movement with
their hip extensors. It should be noted that on the graph below, we are assuming a quasistatic model, i.e., there is no momentum and that the lifter is not actively preventing the
weight from swinging past 90º of hip flexion.
Below is a graph showing the torque-angle curves of the previous four exercises if a 6’, 200
lb subject were to hold a 100 lb weight at the top of his or her chest.
Hip Extension Torque (Nm)
Hip Extension Exercise Torque-Angle Curves
600
500
Good Morning
400
45º Back extension
300
200
100
0
90º
2 x 4: Maximum Strength
135º
Hip Angle
180º
Horizontal Back
Extension
Reverse Hyper
Page 42
Glute Ham Raise
Just like the name says, the GHR is an excellent movement for the development of one’s
hamstrings, but as far as the glutes go, it is a bit of a misnomer. This is due to the fact that
knee flexion is the bottleneck: one has a much higher capacity for hip extension torque than
knee flexion torque, but the GHR puts a lot more torque on the knees than it does the hips.
It is performed on a glute ham developer (GHD) by extending at the knees and flexing at the
hips until the body forms an L shape. Once at the bottom, the lifter simply extends at the
hips and flexes at the knees.
Glute Ham Raise Torque-Angle Curves
Torque (Nm)
600
500
400
300
200
100
0
Knee: 180º
Hip: 90º
Knee: 180º
Hip: 135º
Hip Extension Torque
Knee: 180º
Hip: 180º
Knee: 135º
Hip: 180º
Knee: 90º
Hip: 180º
Knee Flexion Torque
As you can see, the GHR is a knee dominant (knee flexion) exercise and not a hip dominant
exercise. For more information on the Glute Ham Raise, check out Bret’s article on T-Nation,
Gutting the GHR.
Barker, P. J., Hapuarachchi, K. S., Ross, J. A., Sambaiew, E., Ranger, T. A., & Briggs, C. A.
(2013). Anatomy and biomechanics of gluteus maximus and the thoracolumbar fascia at
the sacroiliac joint. Clinical Anatomy.
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