Thursday, April 29, 2010

Kettlebell Swings: harder than Circuit Weight Traning; easier than Treadmill? How can this be?

ResearchBlogging.orgThere's a new study in English of Kettlebells that shows 12mins of  two handed swings is tougher/harder than circuit weight training, but not as hard as treadmill work. That's probably a surprise for folks used to swinging kettlebells, and certainly how kettelbells have been promoted as an amazing, tough, cardio conditioning endurance tool, where more is more.  What this great new study does, therefore, is help us ask some questions about studying kb's. It also gives us new ways to think about where kb work might be situated relative to other activities. So this post is a wee overview of one of the first english language, peer reviewed articles on Kettlebells.

There's not a lot of english-based research on the effects of using kettlebells. In the latest Journal of strength and Conditioning, though, there is a small paper looking specifically at a 12 min 2 handed swing protocol. The authors credit this protocol as "Dept of Energy Man Maker" described in Pavel Tsatsouline's Enter the kettlebell. Just a note, however: the protocol from what is in Enter the Kettlebell is a wee bit different than what these sudy authors use - it's looser. Here's Tsatsouline's description:
The Man Maker is a painfully simple workout that was devised and implemented at a federal agency’s academy by Green Beret vet Bill Cullen, RKC. Its template is simple: alternate sets of high-rep kettlebell drills—swings in our case—with a few hundred yards of jogging. Do your swings “to a comfortable stop” most of the time and all-out occasionally. Don’t run hard; jogging is a form of active recovery. Senior RKC Mike Mahler prefers the jump rope to jogging, another great option.

Indeed, the protocol is even less specific in Bill Cullen's founding eponymous article describing it.
Do 10 to 75 snatches with each arm depending on your ability level, be sure that you use good form, dig your toes in, and at the top of your snatch or swing hold for a second. Breathing is important, get a good rhythm going. Once done with your snatches jog -don’t run! - quarter of a mile, jogging lets your heart and body recover, if you are running fast it means you didn’t do enough repetitions with your KB.

Continue this routine for 2 miles or farther or till you leave a lung on the ground. This is a fat buster and a cardio gut check but the great thing is you can always make it harder or easier by tweaking the number of repetitions. 
Note that the quantifier in Cullen's work is distance rather than time and number of snatches rather than time. The protocol tested in the study is, by contrast, more specific. It's 12 mins of 2 handed swings.  Not sure where 12 mins came from, but the version run in the study is described in three different ways. First, the abstract describes it as "a kettlebell exercise routine consisting of as many 2-handed swings as could be completed in 12 minutes using a 16-kg kettlebell." I initially thought this meant "continuous" swings. But, in the article itself - thanks to Mike Reid, RKC for pointing this out, it is described as "Subjects performed 2-handed swings, in accordance with
the routine’s published description, for 12 minutes in duration." Er, and that would mean? Sets of high reps with jogging? No, because later it reads:
Subjects completed a 12-minute exercise bout, known as the ‘‘US Department of Energy Man-Maker’’ (ETK). The bout consisted of performing 2-handed swings, using a 16-kg kettlebell (Perform Better, Cranston, RI) for 12-minute duration. A 16-kg kettlebell was used in this study because that is a recommended weight for beginning men (ETK). Subjects were told to work at their own pace, resting as needed, while aiming to complete as many swings as possible in the 12-minute time frame. Heart rate was monitored continuously and recorded every minute of the bout.
Ok, so what is not the man maker is that (a) time is fixed at 12 mins (b) there is no active recovery, one is "working at their own pace" rather than, in Cullen's case of this routine being a "smoker" as hard as possible. I'd nay be inclined to call this the man maker, then. More "swing at your own pace, stopping as often as necessary, to get as many swings in as possible for 12 mins"

Standard benchmark tests for max heart rate and vo2 were taken; then during the actual kb trial, VO2 and HR levels were recorded throughout the 12 min swing set. The study looked at just this one kb experience. Results varied pretty wildly among participants (10 "active" men).
Subjects completed an average of 265 plus or minus 68 swings during the 12 minutes, for an average work rate of 22 plus or minus 6 swings per minute.
Ok, looking at the numbers, 12 mins of swings, does this sound like a man maker to anyone who's focused on a "smoker"? Just looking at myself, a wee 5'6", 60kg female, i do 100 swings for recovery during RTK with a 12 or 16 - i just checked with the 16 - it's 2 mins and a bit. So i'm mystified at how non-manmaker'ish (ie "smoker") this protocol must have been run.

Even given that "active men" were doing this, the results seem to have a heck of a standard deviation in such a small sample size, eh? I'm curious about how many times people stopped. Did the person with the lowest score only stop once? Did the best score recover frequently? That would be interesting to know. 

Main results: during the kb effort, %HRmax was "significantly higher (p<0.001) than average VO2max. That's a bit of a surprise. One would usually expect that %HRmax would be strongly corelated to predicted VO2max. For instance, 85% MaxHR should connect with about 75% VO2max  (see calculation here). In this small study of "active men" however,
The equation describing the regression line to predict %V̇o2max from %HRmax was %V̇o2max = 0.714%HRmax − 4.57, with a significant correlation of 0.58 and an SEE of 6.6%. Figure 2 illustrates the relationship between %V̇o2max and %HRmax.
That resulted in an 85% max heart with 65% V02max

What the results of the study mean
These results show that, at least according to the ACSM, the KB 12 min swing circuit rates as "hard". Second, the respiratory exchange ratio (RER) shows that the 12min effort means that this workout is high in "non-oxidative metabolism." That means that these 12 mins are not primarily fat burning minutes - calorie burning yes, but where many of those calories are coming from sources other than fat. But these results do suggest, that at least in this protocol, this is not a hugely stimulating protocol for enhancing Vo2max.

So again, i'd say that the way this protocol must have been run was out for a stroll with the 16, it still shows a pretty durn good effect, cardio wise.

Where does this KB workout Fit?
In terms of other similarly tested workouts - circuit weight training (see description of cwt here, mid port) and treadmill running, amazingly, it's higher than circuit weight training but lower than treadmill running.

lance armstrong: two handed kb swing

The authors recommend that this particular protocol is good for cardio training, but that coaches should be aware that the HR cost relative to the VO2 demainds. Treadmill work (where speed and incline are used to push on cardio work).

Moving Ahead
The intent of this study the authors say "was to document the heart rate (HR) response and oxygen cost of performing a kettlebell exercise routine that is intended to improve cardiorespiratory fitness." That's a rather general claim to make about investigating ONE protocol - one way - of working with a kb.

It's also a protocol used in ETK specifically, as "a smoker" as bill cullen called it and as a "man maker" as its name implies. That's pretty much an all out effort for miles not time and "until you leave a lung on the ground." That's not, it seems, how this study ran the protocol. That's ok; just don't call it a particular protocol if that's not the test you're running.

On the high side, it's great to see the formal research running assessments of KB protocols in a comparative, peer reviewed study. A recent American Council of Exercise test shows that kb's are just awesome for Vo2max training in particular - they effectively paid to have Kenneth Jay's protocol for VO2max replicated and tested, but without standard research protocols for running a comparative analysis, or having the protocol peer reviewed.  Indeed, it's at the very least intriguing that the results in that article (shown in the image below) using the snatch got such different results than the swing - that's in 20mins, with 15 secs on, snatching, 15 secs off, as opposed to 12mins, swinging as many reps as possible non-stop.

Not saying there's anything wrong with these results - just that the benefit of the JSCR shorty gives us a way to situate a KB protocol relative to OTHER kinds of training, and the results are a wee bit of a surprise - we tend to think that all kb's all the time are the hardest ass whopping we can get. And, what seems to have been the case here, is that sure, if you're not swinging with intent to get smoked, you don't get smoking results.

But that's ok. Not all protocols, all the time. And that's actually a good thing. We need physiological variety. Now we're learning what kind of variety kb's can deliver - relative to other workouts.

Looking forward to more formal KB research, to learn more about this awesome fitness tool.

Related Resources
Farrar RE, Mayhew JL, & Koch AJ (2010). Oxygen cost of kettlebell swings. Journal of strength and conditioning research / National Strength & Conditioning Association, 24 (4), 1034-6 PMID: 20300022

1 comment:

Wilson said...

Excellent review, and thanks for sharing the link.

As you point out, there are multiple protocols that could correctly be called 'man maker'.

On the other hand, it's quite clear that the study protocol isn't one of them.


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