Kettlebell Power Production ?

[Waffles03]

There was a research done by Brandon Hetzler (Science of the Swing) claiming that the kettle bell swing maximum power production is seen with a 30% bodyweight. He also mentioned that with heavier kettle bells, you have to focus your more on balancing yourself so you won't be pulled forward by the momentum of the kettle bell. My question is, when you get stronger with the barbell squat, press and deadlift, does that 30% bodyweight for power production goes out the window since your overall strength goes up? Also, would it also make more sense to continue to go up in kettlebell weight when doing the swings in order to get stronger with the swings? Thank you.

 

[Antti]

An interesting question. I'd love to hear an answer to it.

As an aside, has anyone compared the kettlebell swing maximum power production to the maximum power production of the olympic lifts? I'd expect the olympic lifts to be well researched and that there would be a lot of similarities between the ballistic exercises.

 

[Shahaf Levin]

My question is, when you get stronger with the barbell squat, press and deadlift, does that 30% bodyweight for power production goes out the window since your overall strength goes up?

I'll take a shot at it...
The 30% number is related to the KB swing only, not some one-fits-all number for all lifts. As the OP said, probably due to increased balance demands that takes away power. So the 30% goes out the window with barbell lifts just because it has no relation to them.

If I remember correctly 75% of 1RM is a common place to look for ones maximal power production in a back squat. I tested it a couple of years ago by videoing myself, using Kinovea software to calculate bar speed and compute power, than plotting a curve using data from 5 squats with different loads. I don't remember the number, but the curve peak was around 70%... and more importantly than %, I had an actual number to load the bar with.

 

[Anna C]

when you get stronger with the barbell squat, press and deadlift, does that 30% bodyweight for power production goes out the window since your overall strength goes up? Also, would it also make more sense to continue to go up in kettlebell weight when doing the swings in order to get stronger with the swings?

Great questions and post.

I'm thinking the 30% is still applicable. A baseball pitcher can still throw a baseball better and more powerfully than a heavier object even if he gets stronger. Whether he is stronger or not, it requires more power to throw a shotput or heavy rock, but it doesn't allow him to maximally express his power in the throw.

On the second question, absolutely. It takes more power to swing heavier, even it it's not the optimum application of it. Power, strength, and skill are all challenged and developed. You can always return to the lighter weight to maximally express power above all other qualities.

 

[Bill Been]

Plus Five Internets to the first person who can explain the difference between "Force" and "Power".

Plus Two Internets if you can tell whether "power", "force", or some other quantity are being presented in the linked article.

Five Moare Internets if you can apply that knowledge to raise legitimate concerns about the data presented and the conclusions drawn in the linked article.

 

[Anna C]

Well... I would say that force is the amount of strength applied against a resistance, and time doesn't matter. Power is force applied quickly, so there is a time component.

The article discusses power, but the measurement and graph are force.

I suppose in a swing, I could use the same force to swing 24kg, 32kg, 40kg, etc... but I would need to apply that force over more time (milliseconds) -- i.e., use more power in total -- to get the bell up to a standard height with the heavier bells.

In reality, I probably use less force to swing a lighter bell -- but in a true hardstyle swing, I should not. I should use my maximum power, like a punch... I just need to apply that force in a very quick burst, just enough to propel the kettlebell. So true mastery of the "volume knob" concept is to vary the time component of power, NOT the force component.

 

[Im out]

when you get stronger with the barbell squat, press and deadlift, does that 30% bodyweight for power production goes out the window since your overall strength goes up?

No. I say overall strength has nothing to do with it. 30% body weight for me = 20 kg, so once I started one-arm swinging 24 kg (36% bw) I had to work hard to stay on my feet properly. This means spending more focus on balance, anti-rotation and less focus on power production.

Also, would it also make more sense to continue to go up in kettlebell weight when doing the swings in order to get stronger with the swings? Thank you.

Yes because swing strength has little to do with barbell strength if you ask me. I could pull 2.3 body weight DL and 2x bw squat before I started kettlebell training, and I had to start swinging with 16 kg

Besides, once you get to swing bells heavier than 30% of body weight you will work on balance, anti-rotation (in the case of 1hs) and once you get better at that, you will see your power production is sufficient to swing shoulder high.

I do believe there is a diminishing return. I suppose it happens when you can no longer swing shoulder high. Or as high as you usually could with the previous bell

My thoughts on your questions.

 

[Kenny Croxdale]

There was a research done by Brandon Hetzler (Science of the Swing) claiming that the kettle bell swing maximum power production is seen with a 30% bodyweight.

Research?

The information is somewhat interesting. However, there no research data (References) to the information presented.

Percentage Based On Body Weight

The method employed in determining training for Speed and Power (Strength, as well) is based on an individual 1 Repetition Max. It not based on a percentage of an individual body weight.

Two individual may weight the same but have two complete different Strength Levels.

Traditional Exercise Training Percentages

Research and anecdotal data have clearly proven there are specific training percentages for traditional exercise such as Squats, Bench Press, Deadlift, etc for...

1) Speed Training: Load of 10 to 40% of 1 Repetition Max, with around 30% being the sweet spot are the most effective.

2) Power Training: Loads of 48 to 63% of 1 Repetition Max are the most effective.

Olympic Lift Power Training Percentages

Research found that Load of of 70 to 80% of 1 Repetition produce the highest Power Output.

Kettlebell Swings

Kettlebell Swings are more inline with Power Training Percentages of Olympic Lifts. A heavier Kettlebell must be used in order to maximize and develop Power Output, as with Olympic Movements.

Research by Dr Bret Contreras demonstrates that in...

Are Heavy Kettlebell Swings Better Than Deadlifts? | T Nation

Contreras' research demonstrated that a Hip Hinge...

1) 70lb Kettlebells produced 1,935-2,140 Newtons of Foce.

2) 140 lb Kettlebell produced 2,325-2,550 Newtons of Force.

Thus, there the 140 lb Kettlebell Swing produced around 20% more Power Output than the 70 lb Kettlebell.

Olympic Lift vs Kettlebell Swing Power Output

Olympic Lift Movements have produced some of, if not, the highest Power Outputs in Sports.

Heavy Kettlebell Swing's Power Output rival an Olympic Lift Movement.

When Your Strength Goes Up

The foundation of Speed and Power Training is based on Limit Strength (1 Repetition Max) in a movement.

When you Limit Strength increases in a movement, you will see an increase in Speed and/or Power.

That means that once your Limit Strength increases you need to recalculate your Speed and/or Power Training Load by utilizing the Training Percentages.

Kenny Croxdale

 

[Kenny Croxdale]

As an aside, has anyone compared the kettlebell swing maximum power production to the maximum power production of the olympic lifts? I'd expect the olympic lifts to be well researched..

Olympic Lifting Power Output Research

Work by Dr John Garhammer, a biomechanist at the Department of Physical Education at California State University reveals some interesting comparisons between exercises in the development of power. ..."A Review of Power Output Studies of Olympic and Powerlifting: Methodology, Performance, Prediction and Evaluation Test",
... (w/kg = watts per kilo of body weight):

During Entire Snatch or Clean Pull Movements:
34.3 w/kg Men
21.8 w/kg Women

Second Pulls:
52.6 w/kg Men
39.2 w/kg Women

Source: The No Deadlift Program to Improve Your Deadlift

...there would be a lot of similarities between the ballistic exercises

Definitely! Great point.

Kenny Croxdale

 

[Steve W.]

Okay, I'll play.

Plus Five Internets to the first person who can explain the difference between "Force" and "Power".

Force = mass x acceleration. Power = work/time (work = force x displacement which is also equal to any change in the total mechanical energy of the system). There is also the factor of the angle between the force and displacement vectors.

Plus Two Internets if you can tell whether "power", "force", or some other quantity are being presented in the linked article.

The data in the article refers to force, although the discussion seems to use force and power interchangeably. There are also no parameters given for the force measurements. Are they peak forces, averages over the range of motion of the swing, or what? Since no time parameter is given for the force measurements their relationship to power is unclear. I believe these are also ground reaction forces measured with a force plate, not measurements of forces acting directly on the kettlebell.

Five Moare Internets if you can apply that knowledge to raise legitimate concerns about the data presented and the conclusions drawn in the linked article.

Since data presented is force and the stated conclusion is about power, it is not clear how the conclusion was arrived at. What are the relevant time parameters to determine power? The fact that the parameters of the force measurements are not clearly explained make it even more difficult to see the relationship between the data and conclusion.

But this just means that the connection between the data and the conclusions is unclear. There are also a few reasons I would question the accuracy of the conclusions.

Let's look at power as work/time. Although there may be value in looking at peak impulse (force/time) and I'll comment on that below, let's start by looking at the total time of a rep and the total work done during that rep. At the top of the swing, the KB is floating so its total mechanical energy is all potential (m x g x h). At the low point of the swing, the potential energy is lower because the height is at its low point, but the bell has a lot of kinetic energy (.5 x m x v2 -- velocity squared). At the top of the back swing, the KB is again motionless, so its energy is all potential again, but less than at the top because the top of the back swing is lower than the top of the up swing.

So in looking at the difference in power between reps with different masses, the relevant question is, "How much different is the total time/rep between a lighter KB and a heavier one?" We know the differences in the masses, and the heights at the top and bottom of the swing are basically the same regardless of mass (although a couple of complicating factors are if the lifter can't swing the heavier bell to the same height as the lighter one, and the extent to which the lifter might be forcibly arresting the height of the up swing). So the heavier bell will require more power because of it's greater mass, but is this mitigated or outweighed by a lower average velocity/longer total time? I don't know the answer to this question.

The article mentions that the eccentric force increases with bell size. The eccentric phase of the swing is largely negative work because the force exerted by the lifter is in opposition to the displacement (although the angles are not straightforward) and acceleration is negative (the bell ends up at zero velocity at the end of the back swing). My question would be, if the negative work on the back swing keeps going up with bell size, why isn't that proportional to the postive work the lifter had to do on the up swing? I don't know the answer to this question.

Now I'd like to consider the force measurements in the article as if they are peak force measurements (speculatively, since the article does not make it clear that this is the case). One thing I've noticed in moving up in bell sizes is that with a lighter bell, you can explosively INITIATE the hip drive and gun the bell out of the hole. With a heavier bell, you have to ramp up the power of the hip drive and explosively FINISH the hip drive for maximum power. So I can imagine that there is a sweet spot where peak impulse might be higher with a given bell size (depending on the strength of the lifter) and decrease with a heavier bell. But whether this could be defined as higher power would depend on the time frame you are using to define power. I also don't know whether this would be more a function of bodyweight or the strength and skill of the lifter.

Finally, the idea in the article that lower power is produced with heavier bells because of the need to stabilize seems extremely speculative, but is presented as a definite unqualified fact. How was this determined?

@Bill Been, do "internets" have cash value? Are they like Bitcoin?

 

[Anna C]

One thing I've notice in moving up in bell sizes is that with a lighter bell, you can explosively INITIATE the hip drive and gun the bell out of the hole. With a heavier bell, you have to ramp up the power of the hip drive and explosively FINISH the hip drive for maximum power. So I can imagine that there is a sweet spot where peak impulse might be higher with a given bell size (depending on the strength of the lifter) and decrease with a heavier bell. But whether this could be defined as higher power would depend on the time frame you are using to define power. I also don't know whether this would be more a function of bodyweight or the strength and skill of the lifter.

Brilliant. Totally agree.

 

[Bill Been]

Okay, I'll play.

Force = mass x acceleration. Power = work/time (work = force x displacement which is also equal to any change in the total mechanical energy of the system). There is also the factor of the angle between the force and displacement vectors.



The data in the article refers to force, although the discussion seems to use force and power interchangeably. No There are also no parameters given for the force measurements. Are they peak forces, averages over the range of motion of the swing, or what? Sinc no time parameter is given for the force measurements their relationship to power is unclear. I believe these are also ground reaction forces measured with a force plate, not measurements of forces acting directly on the kettlebell.



Since data presented is force and the stated conclusion is about power, it is not clear how the conclusion was arrived at. What are the relevant time parameters to determine power? The fact that the parameters of the force measurements are not clearly explained make it even more difficult to see the relationship between the data and conclusion.

But this just means that the connection between the data and the conclusions is unclear. There are also a few reasons I would question the accuracy of the conclusions.

Let's look at power as work/time. Although there may be value in looking at peak impulse (force/time) and I'll comment on that below, let's start by looking at the total time of a rep and the total work done during that rep. At the top of the swing, the KB is floating so it's total mechanical energy is all potential (m x g x h). At the low point of the swing, the potential energy is lower because the height is at its low point, but the bell has a lot of kinetic energy (.5 x m x v2 -- velocity squared). At the top of the back swing, the KB is again motionless, so it's energy is all potential again, but less than at the top because the top of the back swing is lower than the top of the up swing.

So in looking at the difference in power between reps with different masses, the relevant question is, "How much different is the total time/rep between a lighter KB and a heavier one?" We know the differences in the masses, and the heights at the top and bottom of the swing are basically the same (although a couple of complicating factors are if we can't swing the heavier bell to the same height and the extent to which the lifter might be forcibly arresting the height of the up swing). So the heavier bell will require more power because of it's greater mass, but is this mitigated or outweighed by a lower average velocity/longer total time? I don't know the answer to this question.

The article mentions that the eccentric force increases with bell size. The eccentric phase of the swing is largely negative work because the force exerted by the lifter is in opposition to the displacement (although the angles are not straightforward) and acceleration is negative (the bell ends up at zero velocity at the end of the back swing). My question would be, if the negative work on the back swing keeps going up with bell size, why isn't that proportional to the postive work the lifter had to do on the up swing? I don't know the answer to this question.

Now I'd like to consider the force measurements in the article as if they are peak force measurements (speculatively, since the article does not make it clear that this is the case). One thing I've notice in moving up in bell sizes is that with a lighter bell, you can explosively INITIATE the hip drive and gun the bell out of the hole. With a heavier bell, you have to ramp up the power of the hip drive and explosively FINISH the hip drive for maximum power. So I can imagine that there is a sweet spot where peak impulse might be higher with a given bell size (depending on the strength of the lifter) and decrease with a heavier bell. But whether this could be defined as higher power would depend on the time frame you are using to define power. I also don't know whether this would be more a function of bodyweight or the strength and skill of the lifter.

Finally, the idea in the article that lower power is produced with heavier bells because of the need to stabilize seems extremely speculative, but is presented as a definite unqualified fact. How was this determined?

@Bill Been, do "internets" have cash value? Are they like Bitcoin?

This is by far the best technical analysis of any type I've ever seen on this site.

Bra-freaking-vo, Steve W.

PS - see? trolls like me have their value. hashtag winkyface

 

[Steve W.]

This is by far the best technical analysis of any type I've ever seen on this site.

Bra-freaking-vo, Steve W.

Yeah, that high school physics I took 35 years ago still comes in handy once in a while.

PS - see? trolls like me have their value. hashtag winkyface

Absolutely. I said as much in another thread and I meant it sincerely.

 

[Riley O'Neill]

The difference is bell speed and thus peak height. I noticed when I started one arm swinging my 40kg that it generally does not go as high as the 32kg, so its not moving as fast. Each swing uses a pull of energy to move a kettlebell. E = m*v^2. You want the maximum amount of energy in each pulse. As the Velocity is squared moving a kettlebell faster by 10% is more energy intensive than moving a 10% heavier kettlebell the same speed. That is why a heavy swing that goes half way between the belly button and breast is really not as much energy as a lighter kettlebell that goes to chin level.

I figure this is one reason why the swing is not used in GS Sport and why the American swing is used in CrossFit competitions, the maximum height determines a rep and just a few inches less can result in considerable power savings. The swing is 'best' because it is such an inefficient movement and in competition efficiency always wins out.

 

[Anna C]

The difference is bell speed and thus peak height. I noticed when I started one arm swinging my 40kg that it generally does not go as high as the 32kg, so its not moving as fast. Each swing uses a pull of energy to move a kettlebell. E = m*v^2. You want the maximum amount of energy in each pulse. As the Velocity is squared moving a kettlebell faster by 10% is more energy intensive than moving a 10% heavier kettlebell the same speed. That is why a heavy swing that goes half way between the belly button and breast is really not as much energy as a lighter kettlebell that goes to chin level.

I figure this is one reason why the swing is not used in GS Sport and why the American swing is used in CrossFit competitions, the maximum height determines a rep and just a few inches less can result in considerable power savings. The swing is 'best' because it is such an inefficient movement and in competition efficiency always wins out.

I agree with a lot of what you said here, @Riley O'Neill , but not all of it. I can't properly explain it in physics variables, but in either a 1H swing or 2H swing, I would bet you "+5 Internets" that I could line up a series of kettlebells (8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48... although the last 4 only for 2H swings), move down the line with a metronome and swing them all for 5 swings of equal height to each other, all to the same metronome beat. And if I could, I must be adjusting my "volume knob" (whether it's force or power, I'm not sure - but based on my earlier post in this thread I would say power) to the weight of the bell.

 

[Riley O'Neill]

I agree with a lot of what you said here, @Riley O'Neill , but not all of it. I can't properly explain it in physics variables, but in either a 1H swing or 2H swing, I would bet you "+5 Internets" that I could line up a series of kettlebells (8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48... although the last 4 only for 2H swings), move down the line with a metronome and swing them all for 5 swings of equal height to each other, all to the same metronome beat. And if I could, I must be adjusting my "volume knob" (whether it's force or power, I'm not sure - but based on my earlier post in this thread I would say power) to the weight of the bell.

If we change your experiment a bit to how high you can throw each kettlebell and thus when the KB leaves your hands we can get a rough figure on how fast it was going based on how high it goes. I am willing to bet that the kb with the most energy behind it will be somewhere in the middle of the pack. The heavier kettlebells will not go nearly as high, thus their velocity is considerably lower and because E=M*V^2 the decline in velocity is far bigger than the increase in mass.

 

[Anna C]

If we change your experiment a bit to how high you can throw each kettlebell

This would be difficult because generally I swing to project power forward. We did one time go outside for @WxHerk 's "Bombing Run"(somewhere on here, we had some photos of this craziness) throwing 12kg overhead and back as far as it would go. It might have gone as high as 20 feet. I have also thrown them out for maximum distance --the 24kg went about 10 feet. I was disappointed with this at the time, but thinking about the two different weights and events, I suppose the heavier weight slows down much faster, as you said.

We did have some measures of speed in this thread: How fast do we swing Kettlebells?

 

[North Coast Miller]

I agree with a lot of what you said here, @Riley O'Neill , but not all of it. I can't properly explain it in physics variables, but in either a 1H swing or 2H swing, I would bet you "+5 Internets" that I could line up a series of kettlebells (8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48... although the last 4 only for 2H swings), move down the line with a metronome and swing them all for 5 swings of equal height to each other, all to the same metronome beat. And if I could, I must be adjusting my "volume knob" (whether it's force or power, I'm not sure - but based on my earlier post in this thread I would say power) to the weight of the bell.

This would be a good test. My guess is that for most of the travel, the times would be comparable, but the times at the bottom of each swing would cause a lag at heavier loads. The ratio of potential energy to inertia will shift and the initial acceleration will slow down. Not a ton, but would show up over a bunch of reps.

Also, if you were to do these at a leisurely pace with all, the difference wouldn't be there. If you did them as rapidly as you could to the top, and not use extra force to drive the lighter ones down faster, this is where the heavier ones' greater inertia will slow down the move.

Or I could be totally wrong.

I'm not sure what this would have to do with power projection. Power being work over time, I don't see where the 30% would be a factor - it takes more force to move the heavier KB (40%), so even if it did slow down, as long as the travel distance stayed the same and any increase in time was minimal, the amount of power expressed will still be greater (?).

 

[Kettlebelephant]

@B.Hetzler
let's get the man himself get involved in this
He might be able to answer your questions.

 

[Anna C]

I can't properly explain it in physics variables, but in either a 1H swing or 2H swing, I would bet you "+5 Internets" that I could line up a series of kettlebells (8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48... although the last 4 only for 2H swings), move down the line with a metronome and swing them all for 5 swings of equal height to each other, all to the same metronome beat. And if I could, I must be adjusting my "volume knob" (whether it's force or power, I'm not sure - but based on my earlier post in this thread I would say power) to the weight of the bell.

I'm not sure this contributes anything to the discussion, but I'm reporting back on a trial of this assertion.

This morning I lined up an 8, 12, 16, 20, 24, 28, and 32kg. With each bell, I did 5 2H swings, then 5 R, then 5L 1H swings. I could swing them all to the same cadence, until I got to the 1H swings with the 20 and 24 (and presumably would have been the same going heavier) -- these did slow down. With a 2H swing you can continue to swing quickly with a heavy bell by swinging powerfully for a quick ascent to chest level, then arresting the ascent at the top with the lats, pushing it back down, a little bit like a shadow swing or overspeed swing. This isn't really possible with a 1H swing. As @WxHerk put it, "With a 1H swing, the kettlebell has a little more say in the matter."

I also think the 36kg and higher 2H swings would be slower (although I didn't do these this morning), mostly because it becomes very challenging or impossible to speed it up as I described by arresting the ascent. Hmm... maybe THAT's the real reason that shadow swings or overspeed swing are most effective at a certain weight (30% bodyweight or whatever it may be) -- the sweet spot of a challenging weight to make you really generate power on the upswing, but a weight that your lats and abs can handle on the upswing to propel back down. In this case I would say the ideal weight is a lot more a function of an individual's power (hips/glutes) and strength (abs/lats) than it is about their bodyweight.