Author Archives: Bret

Calculating Joint Moments in the Squat

Here’s a complicated biomechanical article on the squat from my colleague Andrew Vigotsky (my former intern who is now smarter than me LOL). Hopefully some of you will be able to understand and enjoy it. Cliff notes: the way most of us fitness bros estimate hip and knee extension torques in a squat is oversimplified and erroneous. I still believe it provides a reasonable estimation for narrow stance squatting, but Andrew makes some great points in this article. Down the road Andrew and I will compare calculations to see how far off the methods are in torques. 

Calculating Joint Moments in the Squat
By Andrew Vigotsky

For many years, people in the fitness industry have calculated joint moments in the squat using the floor reaction force vector (FRFV) method or by assuming the external load is the only force inducing a moment (Figure 1). This method, however, is erroneous for a number of reasons (Winter 2009).

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Figure 1. Calculation of knee (green) and hip (blue) external moment arms using the floor reaction force method or barbell location method. The dashed line represents the ground reaction force, floor reaction force, or center of gravity of the barbell.

  1. Those who utilize the FRFV method often assume the lifter’s center of pressure is the midfoot. However, this has been shown not to be the case, as lifters tend to shift their center of pressure anteriorly during the later phases of the movement (Dionisio et al. 2008).
  2. The traditional FRFV method is myopic in that it only examines the sagittal plane. Two-dimensional kinetic analyses become less valid with wider stances and more horizontal abduction (Escamilla et al. 2001), as the other planes cannot be ignored. So, while some believe that hip and knee moment requisites decrease with wider stances, this is not the case. In actuality, it appears that widening one’s stance increases the knee moment arm and decreases the hip moment arm, but only by about 3 cm (Escamilla et al. 2001).
  3. This method ignores superincumbent weight and how joint reaction forces and segmental moments of inertia affect joint moments. These differences are summated in multisegmental models and, especially during dynamic movements, lead to erroneous interpretations of joint moments (Winter 2009) (Figure 2). In reality, inverse quasi-static or dynamic analyses are needed for more accurate calculations. However, in the squat, this may not be as relevant.

Figure 2. FRFV may lead to erroneous interpretations of joint moments as you go up the kinetic chain. This would imply that walking would require some serious neck strength (torque)!


Figure 3. Quasi-static analysis of the squat.

Proper inverse quasi-static analysis of the squat has been shown to be 99% as effective as inverse dynamic analyses (Lander et al. 1990), and is much, much easier to conduct, as segmental angular accelerations may be ignored. Such analyses can be performed using the ground reaction force, segment angles relative to horizontal, segment lengths, segment masses, and segment center of masses (Figure 3). This is, however, much more intense than the FRFV method described above. So, in an effort to increase the validity of the FRFV, it is important that other planes (i.e., transverse plane) be taken into account when attempting to calculate knee and hip moments. In order to take these into account, the joint center must be extrapolated into space, such that the force from the load is perpendicular to it. Only then can the moment arms and moments be calculated (Figure 4).



Figure 4. Aerial View – Top left: narrow stance squat in the transverse plane with moment arms drawn in the sagittal plane. Top right: wide stance squat with moment arms drawn in the sagittal plane. Bottom right: wide stance squat with moment arms drawn in the plane of the joint axes of rotation.

From Figure 4, it can clearly be seen that only examining the sagittal plane can be misleading. These figures are supported by Winter’s support moment theory, in addition to the findings of Escamilla et al. (2001), wherein horizontal abduction resulted in similar summed moment arms, but a bias for a larger moment arm about the knee.

This is one simple example of how biomechanics is not as simple as many may think. In this case, because humans move in three dimensions, calculating things in two dimensions may be shortsighted.


Dionisio VC, Almeida GL, Duarte M, and Hirata RP. 2008. Kinematic, kinetic and EMG patterns during downward squatting. Journal of Electromyography and Kinesiology 18:134-143.

Escamilla RF, Fleisig GS, Lowry TM, Barrentine SW, and Andrews JR. 2001. A three-dimensional biomechanical analysis of the squat during varying stance widths. Medicine and Science in Sports and Exercise 33:984-998.

Lander JE, Simonton RL, and Giacobbe JK. 1990. The effectiveness of weight-belts during the squat exercise. Medicine and Science in Sports and Exercise 22:117-126.

Winter DA. 2009. Biomechanics and Motor Control of Human Movement: Wiley.

Random Thoughts – When Being Anatomically Jacked Can Benefit You and A Valgus Collapse Epiphany

Hi Fitness Brothers and Sisters! Here are 10 random thoughts/things for you.

1. Being Anatomically Jacked Up Isn’t Automatically a Life-Sentence

Check out Lamar Gant in 1988 deadlifting 672 lbs at 132 lbs bodyweight. This is still an all-time record to my knowledge.

He also hit 634 lbs at 123 lbs, which you can see HERE.

Here’s what’s crazy – see HERE for an article discussing how Gant’s 74-80 degree scoliotic spine would compress and bend to a 90-100 degree curvature which would cause him to shrink 3 inches before the bar left the ground. His scoliosis already makes him 3-4 inches shorter due to the curvature, and the compression from the lift causes him to lose another 3 inches, which is why he locks out the deadlift at his kneecaps. See the pictures below.

Gant lamar-gant-scoliosis lamargant1

Now check out Stuart Jamison.

Last week he pulled 628 lbs at 132 lbs bodyweight. Click HERE to see the video.

Stuart’s story is incredible – click HERE to read about it. He has half a rib cage, scoliosis, kyphosis, spina bifida, and diastematomyelia (a split in the spinal column). He wasn’t supposed to live past the age of 2 yrs old. But now he’s a deadlifting machine. See the pics below – he also locks out his pulls at his knees just like Lamar.

stu Stuart Jamison

What’s the moral of the story?

Don’t let your disabilities define you. Rise above. Figure out ways around them. Prevail.

And if their spines can tolerate deadlifting, chances are your body can tolerate more than you think. I see so many people fall victim to Nocebo effects because their doctor or physical therapist or chiropractor told them that they have a leg length discrepancy, or their SI joint was jacked, or their glutes don’t activate, or they have an imbalance.

Trust me, your imbalance isn’t as bad as Lamar’s or Stu’s. I’m not saying that everyone should squat heavy or deadlift heavy (see an article HERE I wrote for a good counterbalance to this post), I’m just saying that you’re probably not as jacked up as you think.

2. Lightbulb Moment – Valgus Collapse and Quadriceps Contractions

I’ve written like five different detailed articles on knee valgus and I’ve scoured the research and racked my brain trying to come up with the responsible mechanisms. Long ago, I realized that it’s not often weak glutes that are responsible for knee valgus since many Olympic lifters and powerlifters cave inwards at the knees. Hell, I cave sometimes and I can hip thrust 725 lbs. Many of my clients with the strongest glutes still cave. Last year, I speculated that it could be quadriceps moment arms that are responsible, but I couldn’t find any literature on it. However, all you have to do is check out the video below to see what happens to the knees when you contract the quadriceps.

You will notice hip internal rotation and inward foot flare!

In contrast, check out what happens when you contract the glutes.

You will notice hip external rotation and outward foot flare!

This realization is a VERY, VERY, VERY, VERY, VERY big deal for biomechanics and indicates that knee valgus is natural and not necessarily due to weak glutes.

So why didn’t I write this up in a separate article and dedicate a big amount of attention to it rather than just toss it into a random thoughts post? Good question – I’m too busy getting my shit together for Norway.

3. Norway Bound

Tomorrow I leave for Oslo, Norway, I’ll be speaking at the AFPT Convention. I have 24 hours of flying, layovers, and driving until I reach the destination, so tomorrow is going to fucking suck. I’m 6’4″ which makes traveling even more unpleasant as the seats are always highly uncomfortable. But our itinerary is legit and it’s going to be a fun trip – I just have to make it there without losing my mind. I’m very excited to meet and present to Norwegian coaches, trainers, and fitness enthusiasts. One thing I’ve realized over the past couple of years is that Norway is big on glute training!

4. Barcelona Bound Later in the Month

On the 23rd of this month I’ll be heading to Barcelona, Spain to speak at the Planeta Barcelona convention.

5. Bropocalypse in Sydney, June 2016

Next June, I’ll be presenting with my buddies Brad Schoenfeld, James Krieger, and Alan Aragon in Sydney, Australia for the Bropocalypse: Evidence-Based Nutrition and Training Summit 2016. Prepare to get rocked! HERE is how Urban Dictionary defines Bropocalypse, so make sure you bring your A-game.


6. Recent PRs

I had a great week of training this week. I’m hovering at 230 lbs. Below you’ll see Thursday’s workout:

Front squat 285 x 3, 315 x 1 (I’m aware of my elbows dropping)
Incline press 260 x 3, 275 x 1
Hip thrust 635 x 3, 725 x 1
HS row 360 x 8, 360 x 10

And below is Friday’s workout:

Full squat 385 x 3, 405 x 1 (I’m aware of serious forward lean/good morning)
Bench press 305 x 1, 275 x 3
Deadlift 525 x 5
Underhand grip lat pulldown 245 x 6

Sorry for the video formatting – I filmed with the iPhone on its side and this always happens when I embed into my blog (doesn’t happen on YouTube or Instagram though). Many of these lifts were personal bests at this new weight (I was 250 lbs for much of the last 2 years), but the deadlift was an all-time 5RM PR and the hip thrust was an all-time 1RM PR.

7. Glute Lab & Office

The Glute Lab is thriving lately. My Glute Squad currently consists of over 10 ladies. It’s challenging training them all at once but what’s cool is that the experienced members are taking leadership roles and helping out the newer members, which makes things ten times easier on my end.

It's a tough job, but somebody's gotta do it. #glutelab #gluteguy #glutesquad

A photo posted by Bret Contreras (@bretcontreras1) on

In addition, this week I outfitted my very first office. I’m very proud of it and have been working away with a smile on my face. A grown man needs his own man cave.

8. Chris Beardsley’s Recent Squat, Deadlift, and Split Squat Pages

Chris Beardley’s recent Research Reviews have been a huge success. Click on the links below to see all the biomechanical reseearch pertaining to the:



Split Squat

9. Basketball Anatomy

Check this out! Rob Panariello, frequent contributor on, recently co-authored a book with Brian Cole called Basketball Anatomy.


10. Narcos

I just started watching Narcos on Netflix – it’s based on Pablo Esobar. Holy shit, what a story! He was pulling in 60 million dollars per day and had to bury his money as he couldn’t launder it or bribe or spend it quickly enough. Obviously I don’t support dealing drugs, but these stories fascinate me nevertheless.

narcos0003That’s it for now fitness peeps! Wish me luck in Norway.


All About Box Squats

Ever since I started following Louie Simmons and Dave Tate around 15 years ago, I’ve heavily incorporated box squats into my personal training. I do agree that raw powerlifters should focus more on specificity and perform free squats more often, but this does not mean that they shouldn’t incorporate the box squat throughout the year during specific phases. That said, I can say with absolute confidence that the box squat is highly beneficial for the general personal training client as it teaches them how to sit back and rely on their hips for propulsion in the squat. After a 6-8 week box squatting cycle, you will find that clients gain tremendous box squatting strength that carries over to their free squatting and positively alters their kinematics. Here is a 15-minute video discussing all aspects of box squats.

I hope you enjoy the video and learn a thing or two about box squatting.

box squat

September Strength & Conditioning Research Questions

Hi fitness folks! Do you know the answer to the September S&C research review questions? If not, you ought to subscribe to our research review service. To subscribe, just click on the button below and follow the instructions…


Strength & Conditioning, Power and Hypertrophy

  1. Is block periodization best for strength—power training in track and field?
  2. What factors are important when using block periodization in track and field?
  3. What field tests are associated with track and field ability?
  4. Can eccentric training enhance strength and flexibility in national-level track sprinters?
  5. Does sled towing improve sprint running speed in youths of all ages?
  6. Do anabolic signaling responses differ between high-volume and high-load workouts?
  7. Is high-volume resistance training better for increasing strength and size?
  8. Do cluster sets allow greater volume loads to be performed?
  9. Does variable resistance training increase strength and size more than constant load training?
  10. Can manual resistance increase strength as much as conventional resistance training?
  11. Does plyometric training improve soccer-specific performance in youth soccer athletes?
  12. Does plyometric training change muscle fiber type?
  13. Do resistance training and plyometrics improve sprint running ability in youth soccer athletes?
  14. What determines pull up performance in trained athletes?
  15. Does post-exercise cold water immersion impair muscular adaptations to resistance training?


Biomechanics & Motor control

  1. Do both pushing more and braking less improve accelerating sprint performance?
  2. Is the hip thrust a better exercise for the gluteus maximus than the back squat?
  3. How does squat variation affect lower body muscle activity?
  4. Does resistance training change the spatial distribution of muscle activity?
  5. How does muscle activity change with relative load during the knee extension?
  6. How does muscle activity change with relative load during the back squat?
  7. Which manual strength testing positions are best for the 3 portions of the gluteus medius?
  8. Are measures of lower body muscle size and 1RM power clean related?
  9. Are maximum isometric strength and vertical jump height related?
  10. How does spine movement differ when the overhead press is performed in front of the head or behind the head?
  11. Is the repeated bout effect exercise-specific?
  12. Does extracellular matrix remodeling contribute to the repeated bout effect?
  13. Can changes in motor neuron excitability explain the post-activation potentiation effect?


Anatomy, Physiology & Nutrition

  1. Do long-term measures of muscle protein synthesis correlate with gains in muscle size?
  2. Does muscle hypertrophy caused by myostatin inhibition accelerate degeneration?
  3. Is higher protein intake associated with greater muscle mass?
  4. Can diary protein intake increase reductions in fat mass during resistance training?
  5. Does leucine affect anabolic signaling differently from the other essential amino acids?
  6. Can plant-based protein support muscle growth?
  7. What causes the loss of strength relative to muscle size in the elderly?
  8. Does melatonin work for primary sleep disorders?
  9. How do contraceptives affect hormone responses to training sessions in elite athletes?
  10. What are the metabolic effects of non-nutritive sweeteners?
  11. Do resting metabolic rate and lean mass drive energy intake?
  12. Are reduced inhibitory control and increased trait impulsivity key features of obesity?
  13. Is sedentary time associated with visceral fat deposits?


Physical Therapy & Rehabilitation

  1. What causes exercise-induced rhabdomyolysis?
  2. Can gluteus maximus inhibition occur in cases of proximal hamstring tendinopathy?
  3. Do both tendon stiffness and muscle activity change in Achilles tendinopathy?
  4. Is hip muscle exercise more effective than knee muscle exercise for patellofemoral pain?
  5. Is there a difference in pelvic floor muscle activity across the phases of the menstrual cycle?
  6. Is pelvic floor muscle contraction associated with and diaphragmatic motion when breathing?
  7. Do individuals with uncontrolled lumbopelvic rotation activate the psoas major to a lesser extent?
  8. Can the “doming of the diaphragm” technique increase flexibility?
  9. Does PNF stretching cause larger changes in stretch tolerance than static stretching?