Geek numbers

So how does bell size affect power output on the swing? It depends. To a certain extent increasing the bell size can increase power output. The magic number where increasing bell size actually decreases power output is around 30% of our body weight. Above that, and the need to stabilize robs you from applying all your strength to the task at had - projecting the kb forward. Using myself as an example (100kg body weight) my "sweet-spot" bell is the 32kg bell (32% of my bw). Just going from the 24kg bell up to the 32kg bell, my power output jumps 14%. Going from 32kg up to 40kg results in a 2.7% drop in force, and going from 40kg up to 48kg drops my force another 7.6%. 

Force production per kettlebell (in newtons)

Can I swing the 48? Yes. If my goal is maximal power, which bell will get me to my goal the quickest?  The 32kg. For strength, heavier is better. For power, speed is king and the load is the court jester - not really fully understood.

Force production and force:body weight ratio

For me my highest force production comes with the  32kg  (1.866 x BW) on the concentric phase - force production.  However, as the bell size increases, the eccentric loads -force absorption- continue to increase as the bell size increases.  But this is NOT force production - it deceleration.  But, it opens the door to a question Lexus asks on one of their TV ads :"What determines performance? The time it takes to go from 0-60, or the distance it takes to go from 60-0?"  So, again, depending on the goal and the sport/activity going heavy does have it's benefit.

changes in load vs. changes in force

Finally when comparing everything to my snatch weight bell,  increasing the bell size always results in me allays generating more force than I can with the24kg bell.  The grain of salt in this is that increase in force production isn't proportional to the increase in size of the bell.  Meaning, while the 48kg gives me 5.9% more force production than the 24kg bell this comes from increasing my load by 50%.  So a 50% increase in load for a 5.9% increase in performance, not good numbers.  BUT, going up to the 32kg bell (a 25% increase in load) results in performance increase of 14.8%.  Much better.

To wrap it up, increasing the load can only contribute to the power out point to a certain extent.  Once above about 30% of body weight the increase in power output is very nominal - so if power output is the goal heavy isn't better.  Speed is king.  Now, if power is your ULTIMATE GOAL - the swing might not be the best choice in exercise.  WHAT?!?!?!  The swing isn't the best tool - sorry, but no.  There is another KB drill that with the same load that results in significantly more power.  If you are at Level II right now, you are about to be introduced to the drill - if not, go with what you've got, the swing.

Good news!

I met again with the Stats guy last week, and still have a headache from it.  He explained that the reason that answering my question 'is there any difference' has been rather challenging because they have had to essentially create a way to analyze all the different numbers, all the different types of numbers, and all the other data we gave them.  We are simply trying to do a pre / post test where each data point correlates to each individuals FMS score and then analyzing group inclusion outcomes.  Oh, and we are trying to do this for five different types of data.  Doing one of those is simple, doing all of them has proven very troublesome.

BUT, THE GOOD NEWS is that at this point there are significant differences!  So everyones time - Dustin, Brett, Jeff, Geoff, Dave, and all participants and data collectors- wasn't wasted.  Exactly, what the differences are we don't know yet.  We are still trying to narrow that down.

One way we are trying to narrow it down, is with a survey that all the participants received this week.  We don't just want to say- "Yes, swings and FMS corrective drills are good" or "Swings bad".  We want to really be able to break it down based on the questions in the survey - don't want to give away too much at this point.

So, keep checking back here and once all the numbers are crunched I'll begin posting some really interesting stuff.  And, if you took part in the Study and the Survey and want your results - let me know and I can get all the numbers to you.

And the winner is.........

Well, it depends. With 60% of the votes, public opinion says Pavel. But the force plate shows something different - depending on what the question is. Who generated the most force? Dave (by about 30kg of force), followed by Geoff, myself, Pavel, Brett, and Rush. However, once you put together a force to body weight ratio -so we can compare Rush to Dave- the results are different. The highest force to body weight ratio was generated by Rush at 2.28x his body weight, followed by Geoff (1.82) and Pavel (1.73).

One question I have -and am looking into - is what percentage of bodyweight the kettlebell is. For those of us in the Clydsdale division (200 + lbs) swinging a 24kg bell is a lot different than someone that swings a 24kg bell and weighs 160lbs. For myself (225lbs at the time on the forceplate) the 24kg bell was 24% of my body weight. For Pavel (177lbs) the 24kg bell is 30% of his body weight. To truly be equal, we need to look at myself swinging a 32kg bell and Pavel swinging a 24kg bell - both 30% of our body weight. I will look at this further, but do have a feeling that there is the "perfect" bell out there for everyone that will translate to the highest power production. Too light, and there is not enough mass to get a lot of power. Too heavy, and the mass causes the movement to slow down. The key is to find the heaviest bell possible AND maintain the speed of a lighter bell. To almost quote some smart people, "as soon as the movement starts to slows down" power will be negatively affected - in this instance.

Force to body weight is a very important athletic component. Want to jump off the ground or run? You need to generate at least enough force to equal your body weight to move, and more than your body weight to move higher or faster. Plan on landing or cutting to change directions? You need to be able to control from 2 - 5x your body weight unless you want to get hurt. Mark Toomey asked the question why worry about generating more force on the swing? He pointed out the benefits of bone density, but also the more force you generate on the up swing the more you have to control on the downswing. FYI - Pavels' down swing forces exceed 3x his body weight, which is head and shoulders above anyone else I've seen - including Rush. So, add bone density and improved force control and you may be onto something called injury reduction.....hmmmmmm.

Who is the most forceful?

I ended my last post with the teaser regarding who generated more force at the 2011 Summit of Strength -quick plug all the cool people will be at the 2012 SOS!! So I've put my lab coat and spectacles on, got my 2 year old and dog rounded up (so I had plenty of fingers and toes) and knocked out the super complicated mathema-physic-sciency type equations to answer the question: Who generated more power - Master RKC Brett Jones, MRKC Geoff Neupert, or MRKC Dave Whitley. To make things more interesting: I pulled my data on Pavel, threw Data on myself in there, and for fun included the data from MRKC Jeff O'Connors 12 year old son Rush in there.

Before I give the answer, lets get a little poll going. Visit my Facebook page to vote. If we aren't friends, find me - Brandon Hetzler. We will see who the winner of public opinion is and then we will see who the real winner is.

What the forceplate can tell us.

"The language of Movement is feel" -- Gray Cook

When people find out that I regularly have people swing kettlebells on a force plate, the first question I always get is "how do I compare to _________?" With a little time and math I can pretty much tell everyone how they rate compared to - say - Pavel (whose name typically fills that blank most often). While that is good information to have, what can people do with it? More importantly how will that improve their swing? My opinion: knowing your power output won't do anything to improve your technique.


Often times when trying to fix someones technique, we ask the question "how does that feel" or "do you feel the difference?" If someone can't feel what they are doing, how can they feel what they are doing differently? The immediate feedback the force plate gives -that I overlooked until recently- is immediate feedback on swing technique. For example, this is an example of what a swing looks like graphed out on the force plate:

 What this shows is the vertical forces associated with the swing in a graph format. Essentially, it allows me to see the forces being generated during the swing as they are happening - it shows me what you feel. Does your swing feel smooth or jerky? Powerful or weak? Fast or Slow? I can tell you what you feel, then show you what you feel. The swing depicted above is a very smooth swing, a very efficient swing, and a very powerful swing. It also happens to be the swing of Master RKC Brett Jones. You will notice how smooth the curves are, not a lot of jagged edges - this tells me that he is efficiently cycling between tension and relaxation. Notice that during the float phase - when the bell is at the top of the swing and floating- the line is relatively flat. This is Brett appreciating his swing - a moment of "controlled" relaxation where there is little to application of force. You will also notice how the peak of the down portion (bottom) of the swing is much higher than the peak of the up swing (the peak right before hip EXT). This is because significantly higher eccentric forces are created by Brett than concentric forces. Remember Pavel and all the Master's emphasizing having an active down swing where you are actively hiking the bell down and back? This is what they want to see. Why this is important and how this benefits the force produced during the up swing will be discussed in a later article.

Now, lets dissect Pavel's swing:

 First, look at how similar each peak and valley looks. That is consistency thru mastery. Each of Pavels swings are identical to each other. Next, his down swing takes approximately 1/4 or a second and generates a tremendous eccentric load. That is then followed by an upswing that lasts 1/2 a second. Which, because of how quickly the transition from eccentric to concentric occurs Pavel is able to utilize a large amount of the energy he stored during the down swing to power his up swing - think along the lines of a plyometric activity. One difference you will see between Pavel and Brett's swing is that Brett exhibits a "quieter" float phase - which shows that at the top of the swing Brett is better able to relax. Pavel again exhibits consistency during his float phases -they all look the same.

Now lets look at a bad swing:

 Problem #1 - the down swing is horrible. Notice how there is no consistent peak. This is a very slow swing (the down swing was twice as long as Pavels) which leads to a loss of energy -as heat (again like plyometrics). This person also has quite a bit of variability between each swing.
Problem #2- the float phase does not exhibit any relaxation, and is not consistent. With Pavel, he had some activity but it was consistent activity. This person does a poor job generating tension, has trouble relaxing, and demonstrates no mastery of the swing. Their swing might look good, but probably feels very challenging for them - to the point that they get gassed with high volume swings (and even snatches).
Problem# #3 - This is a very slow swing.  From start to finish, one swing cycle takes approximately 1.20 seconds to complete - not counting the float phase.  Pavel took 0.750 seconds, and the Iron Tamer Dave Whitley (Master RKC) takes 0.810 seconds.  This has a dramatic effect on the power that is generated.  Essentially, slow swings generate less force that fast swings.

So lets end on a good note - breaking down the Iron Tamers swing.

Not surprisingly, Mr. Whitley has a textbook swing. Each of his swings is identical to the previous. The eccentric portion took less than 1/4 second, and the concentric portion took just over 1/2 second. His float phase isn't as relaxed as Brett's, but like Pavel there is consistency.

The commonality between all three - Pavel, Brett, and Dave - is the speed of their swing. All three took around 0:750 seconds to complete one swing cycle. We could get into the whole physics of this but essentially with increased swing speed - especially on the downswing - and consistency, power will be there. BUT the other commonality is the float phase - there has to be a controlled relaxation portion of the swing.

Finally, what everyone wants to know: Who generated more force? That will come next time, so stay tuned. I've never claimed to be good at math, so I need to round up some extra fingers and toes to get those numbers.

Uh-oh.....

Met with the Statistician this morning to discuss the Data we collected at the Summit of Strength from the force plate and the FMS. It can't be good when someone that deals with stats for a living says: "ohhhh, you are giving me a headache!"

So you think you can swing?

I once heard someone -Brett Jones MRKC I believe- state that there is a huge difference between swinging a kettlebell and performing a kettlebell swing. The hardstyle swing, though it looks simple, is actually quite technical.

Many people: 1)assume they can teach it to themselves after watching a YouTube clip. 2)think they have enough body awareness to actually do this. 3)pick up poor habits that are hard to break while thinking they are doing a kettlebell swing but are really just swinging away.

You would expect individuals that are planning to attend an RKC course would be proficient at the kettlebell swing. The time invested in preparation should result in good technique, right? Wrong, experience does not equal expertise. The average prep time that individuals spent getting ready for the RKC was 5 months. On Day 1 of the RKC, 79% would have failed to meet the standards of the swing. A majority reported reading Enter The Kettlebell, but only 50% reported meeting with an RKC prior to the course.

The moral of the story - see an RKC instructor to learn how to properly perform the kettlebell swing from the beginning. It will be less frustrating, more efficient, and result in fewer bad habits to break.