Friday, November 24, 2017

Weightlifting shoe studies, and some physics

Suppversity just did a great article surveying various studies on weightlifting shoes and effectiveness.

What is most amazing about these studies, is that almost all of them measured output variables that no one cares about.

For example, one study measured affect on joint angles.  Joint Angles-- no, no, no!  People who buy and wear weightlifting shoes care about 2 things -  injury protection and LIFTING MORE.

How do we measure if a weightlifting shoe is going to help us lift more-- FORCE Output .

 AND,  how the shoe changes the distance of the bar from our center of gravity, such that we are able to lift more. This is sort of related to joint angles, but joint angles misses the mark-- I'll show you why, shortly.

So, if you're thinking of dropping money on a pair of weightlifting shoes, let's go over some basic physics:

1. Force = Mass x Acceleration
         To lift heavy stuff, you must generate a force by accelerating a mass
2. Energie or "work" = Force x Distance
         You create energy by acclerating the mass of the bar over a distance, such as when you pull, squat, or deadlift a bar
3.  Torque =  Force X lever arm distance x sine(of angle which force is applied, most cases its sine(90 degrees) which equals 1
     Torque is the expression of a force that causes rotation. The longer the lever arm distance the greater the torque. If the lever arm is equal to zero, then there is no torque or, rather, you can spin something freely about its center of mass.
     
Things that make you lift More  -- saving you from PR killers !

The oversimplified diagram in red shows a common technical mistake- keeping the bar far from the lifters center of gravity, increasing the amount of work the lifter needs to do to lift the weight.  The green figure shows that keeping the bar closer to the lifter makes the weight easier to lift!  Finally, the black diagram is a grossly oversimplified freebody diagram that, overall, shows that keeping the bar as close to the center of mass as possible will reduce unneeded torque on the bar, making it easier to lift.  *note, toque generated in the lifter's joints is a different subject.



As shown in the cartoon above, if the bar is unnecessarily far away from your body's center of gravity, there will be a greater torque on the bar that you will have to counteract by applying even more force.  This means , you can lift more if you reduce the torque because you will need to generate less force to lift the bar over head or to stand-up with it- as shown by the green figure.  This is true for both olympic lifts, the squat, and the deadlift. The further away the bar is from your body, the harder it will be to lift-- AND the more stress it will put on your spine!

Note --In both cases, the lifter generates force by pushing their feet into the ground.

So, how does this relate to weightlifting shoes, 3 things:

1. A solid heel that minimally compresses will increase force ouput to the ground.

2. A shoe with a stable outsole -- toebox and heel --will also reduce energy lost from poor lateral stability.
-- many weightlifting shoe brands have solid heels, few have a stable toebox. This makes the difference between lifters with feet that barely move (good) and feet that wobble (bad).

3. A shoe with the right heel height will enable the lifter to keep the bar even closer to their center of gravity.
--- This reduces the torque arm

Now, you can measure these cumulative effect of these 3 items by simply measuring force and distance of the bar from the lifters Center of gravity (CG).    As one example, Force can be measured by having a lifter lift on a force plate or load cell.   The distance of the bar from the CG can be measured with optics , also, as one example.

Just for fun, I did an anlysis on a lifter using optics.  $0 was spent on this 15minute study =0. The results, however, give you a good idea of  what actual scientific studies SHOULD HAVE DONE.

The subject lifter's anatomy is as such their torso, upper leg, and their lower leg are all about the same length. That means, their tibia/fibia is about as long as their femur,   and the length of their torso is about half the length of their entire leg (upper leg + lower leg).  There are many lifters with similar body types, whereas a torso that is shorter than the total length of the leg gives a stability advantage in the squat position of the snatch and the clean.

They were asked to do a squat with the same weight in 4 types of foot wear treatments - 1 ) in wood heel Risto weightlifting shoes, 2) in plastic heel nike romaleos 3, 3) in normal sneakers or tennis shoes with almost no heel rise, 4) barefoot.  Many on the internet would say that nike's are the best of the Plastic heel shoes and that the Risto's are the best of the wood heel shoes.

I did not take force measurements since the funding for this study was $0 and 15minutes ;) .

Optics were done with ImageJ software.

Note, the actual measurment lines in the software are not shown. Lines shown are for visual guidance.

The results were quite interesting. As expected, lifting barefoot kept the bar furthest from the center of gravity, which means lifting barefoot makes squatting heavy weights more difficult. It's also interesting to see the lifter's back is the most rounded when squatting barefoot.   The tennis shoes and nike's were almost equal.  The tennis shoes actually seemed to edge out the nike's with respect to distance from center of gravity, but the difference in camera angle may have contributed some error. The back angle looks better in the nike's than in the tennis shoes.  The Risto sports weightlifting shoes had the best bar spacing to center of gravity out of the 4.  The back position of the lifter looks best in the Risto's as well.

In terms of force output, this was not measured. The two weightlifting shoes would undoubtedly win out because of better lateral stability and less compressibility of the heel. The nike had a softer toebox than the risto, so it is possible that the softer toebox could equal bigger force losses.  This would be a good follow-up study to do.

Again, the $0 15min study does have error sources* in it.  What we can really get out of this experiment is that weightlifting shoes are far better than lifting barefoot and (the correct shoe) is better than lifting in tennis shoes.

UPDATE- one comment received is my oversimplification of the bar-lifter system.  As mentioned above , this is a very over-simplifed analysis.

 A more complete model would be seen by applying control theory and modeling the lifter in State Space.

This research paper does just that:  Optimization of Barbell Trajectory During The Snatch Lift Technique By Using Optimal Control Theory Shahram Lenjan Nejadian, Mostafa Rostami and Farzad Towhidkhah Biomedical Engineering Faculty, Amirkabir University of Technology (AUT), 424 Hafez Ave

Here is a more complete description of the lifter's angles:
Snip from: Optimization of Barbell Trajectory During The Snatch Lift Technique By Using Optimal Control Theory Shahram Lenjan Nejadian, Mostafa Rostami and Farzad Towhidkhah Biomedical Engineering Faculty, Amirkabir University of Technology (AUT)

Here is a  model in state space showing more appropriate non-linear equations to model the weightlifter during the snatch. A similar approach can be taken for the squat:
From: Optimization of Barbell Trajectory During The Snatch Lift Technique By Using Optimal Control Theory Shahram Lenjan Nejadian, Mostafa Rostami and Farzad Towhidkhah Biomedical Engineering Faculty, Amirkabir University of Technology (AUT), 424 Hafez Ave

The above isn't actually the full set of derivations. Basically, they do model the torque in the system looking at the Center of gravity of the bar and the lifter. They discuss optimization of torque generated by each of the joints. They discuss optimal bar paths, which --GUESS WHAT-- optimize the drift of the bar from the lifter's centerline (kind of like my crude little diagram above ;).

 Overall, if we did a more complex model we could model the drift in technique relative to the lifter using different shoes.   It's  all similar principles.

We can posit that the over-simplified  $0 15minutes study  does show a benefit of wearing weightlifting shoes.  Weightlifting shoes can help keep the bar closer to your center of gravity, hence , enabling you to lift more with less force - everyone's goal ! =)

The author has 0 ownership or affiliation with the 3 brands tested.

* error sources- variation in camera angle, repeatability of imagej software, order lifter lifted in each treatment. May want to consider doing additional bodytypes.

2 comments:

Peter said...

Good article, always good to see a bit of science. Too much of that "bro" type advice thrown around, so it's nice to have something grounded in reality.

bamgosoocom said...


Fabulous post, you have denoted out some fantastic points, I likewise think this s a very wonderful website.
I will visit again for more quality contents and also, recommend this site to all. Thanks.

Try to check my blog: 오피사이트
(jk)

Lifting in Kazakhstan, Temirtau, Ilyin's former gym

Lifting in Kazakhstan, Temirtau, Ilyin's former gym
In Temirtau, Kazakhstan. Still, unable to do any overhead work from a ligament tear, I'm just rehabbing with pulls to retrain my muscles. Training next to me is the Youth and Junior team of Temirtau. Ilya Ilyin used to train in this facility as a junior. As well as a recent Junior World Champion, Maksim

Snatching 92kg at the Risto Olympia Cup

Snatching 92kg at the Risto Olympia Cup
This was the 2nd highest snatch in all of the USA for 2014 in official competition for women's 69kg weight class. The only athlete to snatch higher was Jenny Arthur with 98kg. At the time, she was lifting for USAW weightlifting club Risto Team.

Oscar Figueroa,Olympic Silver Medalist, World medalist 2009

Oscar Figueroa,Olympic Silver  Medalist, World medalist 2009
Pictured at Salitre with Oscar Figueroa in center.

Popular Posts

Carlos Andica training with Coach Ivan

Carlos Andica training with Coach Ivan

Arnold, Carlos & Joni Andica

Arnold, Carlos & Joni Andica
Right before Coach Ivan consulted Carlos for the 2011 Pan AM Games, where he broke a Pan AM record. These guys were unofficially competing for Risto Team at the 2011 Arnold.

Shoe porn

Shoe porn
Russian boots, classic weightlifting shoes with modern shoe technology. Exquisite full leather upper, wood heel, rawhide forefoot, natural rubber outsole. One of a kind.

Documenting history of singlets

Documenting history of singlets
USAW national team member in Risto Singlet

Ivan in the Warm-up room with the Andica Brothers

Ivan in the Warm-up room with the Andica Brothers

Leidy Solis- PAN AM Champion 2009

Leidy Solis- PAN AM Champion 2009
Leidy in winning form, she's wearing risto weightlifting shoes. Congratulations Leidy!

Exceeding expectations -Archive

Exceeding expectations -Archive
Classic weightliftng shoe design with modern accents. These were produced by Risto Sports

In Iceland

In Iceland

Coach Jonny Pan AM champ

Coach Jonny Pan AM champ
Afternoon coach, doing pwr cleans while his lifters finish up

shoeporn

shoeporn
note pawprints

Abs

Abs
More on Facebook

Shoeporn-Custom Weightlifting shoe history

Shoeporn-Custom Weightlifting shoe history

Documenting shoe history

Documenting shoe history
first commercial shoe marketed to youth sizes

Bucharest Training Center

Bucharest Training Center
Ramanian Coach Doru, Ivan, Romanian Lifter Eiza

Nikolai Stoichkov- JR Bulgarian Lifter, son of Zdravco Stoichkov

Nikolai Stoichkov- JR Bulgarian Lifter, son of Zdravco Stoichkov
Training with a pair of Botev shoes. These shoes take a beating of 18000 to 20000 reps per year and heavy loads 90-100% - Also known as the Bulgarian system.

sweet singlet

sweet singlet

Future Champion- Tough lifters wear pink!

Future Champion- Tough lifters wear pink!
Gwendolyn Rojas getting ready to snatch 60kgs at 20kg bodyweight and 4 years old.

Stoichkov in Action

Stoichkov in Action
Coach Stoichkov adjusting my starting position.

Ivan giving training advice in Frankfurt Oder

Ivan giving training advice in Frankfurt Oder
Here Ivan, as a coach, is giving lifting advice to German Junior lifters at the Olympic Training Center in Frankfurt Oder, Germany. Yes, Ivan is fluent in German and is speaking German to the lifters.

Working out with the Champs

Working out with the Champs
Gwen squatting wth Georgiev, Peschalov, and new lifter in background

Training in Bulgaria - Gwen and Coach Zdravco Stoichov

Training in Bulgaria - Gwen and Coach Zdravco Stoichov
Stoichov is coach of Peschalov, Georgiev, etc. Also of key interest: Similar to USA lifters missing out on their chance to medal at the 1980 Olympics , at the time of the boycotted '84 Olympic Games, Stoichkov outlifted the LA Games Gold Medalist at the Friendship Games/ Druzhba Games. The Druzhba Games were held in 1984 by Eastern bloc countries not participating in LA.

Ivan with Nikolai Gergov, Bulgarian Wrestling Champion

Ivan with Nikolai Gergov, Bulgarian Wrestling Champion
Ivan with the Greco wrestling world champ, Nikolai Gergov, after their workout. I still think its uncanny how elite athletes from multiple sports would just show up at Slavia for a workout (....and atleast one ask for lifting advice). Again, overall, Bulgarian athletes were humble or, rather, didn't "have an attitude" in the gym.

Gewichtheben - training at the German Olympic training center in Frankfurt am der Oder

Gewichtheben - training at the German Olympic training center in Frankfurt am der Oder
Me with the German Junior Team and Coach/German Olympian Lars Betker

Documenting shoe history: Coach Burgener Shoe

Documenting shoe history: Coach Burgener Shoe
A wonderfully patriotic, Americana themed shoe and T-shirt. GO USA!!!

Gwen posing with Peschalov

Gwen posing with Peschalov

Stoichkov during competitive years

Stoichkov during competitive years
Vintage photo of Stoichkov winning international Championship

Rumy, Bulgarian lifter

Rumy, Bulgarian lifter
Rumy,75kg lifter, stops by for a light workout in Slavia, Bulgaria

Botev stops by Slavia

Botev stops by Slavia
Gwen, Stefan Botev (multi-time Olympic Medalist and world champion), and Ivan

Gwen with Power Clean/slpit jerk with 80kg

Gwen with Power Clean/slpit jerk with 80kg
First workout in Slavia.

Size perspective for youtube video

Size perspective for youtube video
In Beijing, junior lifter

Ivan and Eric, the speedskater

Ivan and Eric, the speedskater
After a hard work out, Ivan and Eric go summertime cycling in Maine. Eric is a competitive Speedskater and a proud owner of weightlifting shoes. Ahhh ...nothing like summers in Maine!!

Stefan Georgiev

Stefan Georgiev
World and European Champion, 62kg. Rooting for him to medal in the 2008 Olympic Games!

Hanging out with Weighlifting heroes

Hanging out with Weighlifting heroes
Peschalov, Stoichov, self, and husband

Old Stuff - shoe porn

Old Stuff - shoe porn

Peschalov and Coach

Peschalov and Coach
Peschalov trained with Stoichkov leading up to his Gold medal win in 2000 Olympic Games

Training in Kennedy, Bogota

Training in Kennedy, Bogota

Euvgeni Popov, Stoichov, and Gwen

Euvgeni Popov, Stoichov, and Gwen
Popov - 1980's Bulgarian weightlifting team, also accomplished power lifter and strongman competitor.

Beijing - Gongti Area

Beijing - Gongti Area
Gwen lifting at second training location in Beijing near Workers Stadium, Gongti

Sylvia, Bulgarian Junior lifter, wearing Botev shoes

Sylvia, Bulgarian Junior lifter, wearing Botev shoes
Schoolage Champ, one of Stoichov's newer lifters. Sylvia also trains in Botev shoes. Her pair is also several years old and has lasted over 18K reps per year!

Romania - Training Center in Bucharest

Romania - Training Center in Bucharest
Me trining with Romanian lifters in Bucharest. Former USAW National Coach, Dragomir Ciroslan, had once lifted in this gym.

Wrestling World Champion (Greco) Nikolay Gergov working out in Slavia (BG), me in background

Wrestling World Champion (Greco) Nikolay Gergov working out in Slavia (BG), me in background
Nikolay Gergov is a Bulgarian Wrestling World Champion - Greco Roman 66kg category. Nikolai is already naemd to the 2008 Bulgarian Olympic Team. He is also competing at a meet at the Colorado Springs US OTC later this month (FEB 08). Anyhow, Nikolai just stops by for a workout in Slavia. He saw Ivan and I working out and asked Ivan for some technique coaching.

Gwen with Chinese coach of junior team at Chaoyang Ti Yu Chang (Beijing)

Gwen with Chinese coach of junior team at Chaoyang Ti Yu Chang (Beijing)
The coach pictured with me had won a gold medal in the snatch lifting against Karolina Lundhal (world champion) at the 1998 Worlds in Finland in 75Kg class.

Lifters in Bucharest

Lifters in Bucharest

Ivan with Coach Chiu, gongti area Beijing

Ivan with Coach Chiu, gongti area Beijing
After discussion of Chinese pull technique. Chiu is a former Junior World Champion.

Good Leather Smells good

Good Leather Smells good
Really, this was a Candid photo..."wow, this smells good"

Ivan Lifting in China - 2006

Ivan Lifting in China - 2006
Chinese training center, Chao Yang Ti Yu Chang in Beijing, a JR team pictured in background

Choayang Ti Yu Chang - Ivan with chinese junior lifters

Choayang Ti Yu Chang - Ivan with chinese junior lifters

Abigail Guererro, Almerimar, Spain 2004

Abigail Guererro, Almerimar, Spain 2004
In forefront, Abigail , who has been on the Spanish National Team, with teammates in background.

Me with Blessed Udoh, in Spain (DEC 2004)

Me with Blessed Udoh, in Spain (DEC 2004)
Blessed won the silver medal in 48kg at the 2001 World Championships representing Nigeria. She also trained in Bulgaria for the 2004 Olympics. Sadly to report that she died in Nigeria, last year.

Gwen lifting at Chaoyang Ti Yu Chang - Beijing,

Gwen lifting at  Chaoyang Ti Yu Chang - Beijing,
In Beijing, Chinese Juniors in background. Great kids, good sense of humor, listened to their formal coaches

Spain- Ivan and Miguel Borrazas

Spain- Ivan and Miguel Borrazas
Our good friend Miguel has coached Spain's national team.

Training Bogota

Training Bogota

Ivan with Coach Ediberto Barbosa, fmr Col natl team

Ivan with Coach Ediberto Barbosa, fmr  Col natl team

Mock Competition in Bogota

Mock Competition in Bogota
Gwen out snatches the challenger

Rick Bucinell, breaking master world record

Rick Bucinell, breaking master world record

Ivan arm wrestling Peschalov

Ivan arm wrestling Peschalov
My husband "attempting" to arm wrestle Peschalov with his good arm. Ivan remarked "Wow, he's strong..he was really trying to arm wrestle me" ..no kidding ....ha ha ha

Stuff you need to compete

Stuff you need to compete
Belts, singlets, knee and wrist wraps.

Little Gwen doing workout with new lifters

Little Gwen doing workout with new lifters

Me on Team USA which was sponsored by Risto Sports, 2010 University World Championships

Me on Team USA which was sponsored by Risto Sports, 2010 University World Championships
Me lifting for Team USA. We won 15 medals, Ivan was Assistant Coach to Team USA. We had no official uniforms-- until, THANKFULLY, Risto Sports donated gear such as USA polos and t-shirts, so we could at least match in some semblance of a uniform. The team got to represent our country well!

Tanya Morillas - 2004 in Spain

Tanya Morillas - 2004 in Spain
Training session at Almerimar. Subsequently, Tanya has been on Spanish national teams.

Dare Alabi , 77kg lifter (Nigeria)

Dare Alabi , 77kg lifter (Nigeria)
Nigerian lifter, Dare, lifting in Spain

warming up power cleans

warming up power cleans
Me training in Bogota Colombia