As professional PTs, it's important we look behind the claims at independent evidence-based research to identify the real value for our clients.
One of the many challenges for personal trainers is to cut through the publicity that often surrounds new training methods and tools to identify the benefits that can realistically be attained by their clients. Another is to work out how to extract the fitness and performance value of methods and tools whilst maintaining the fun factor for their clients.
The best PTs combine a rigorous analytical mind-set with a truly pioneering attitude when planning activities for their clients. To do this, they need to recognise the value of independent evidence based research and be able to use it to help them decide whether or not to include it in training programmes for their clients.
In short, the aim is to find out the facts and then make it fun.
With this in mind, what follows is a short review of kettlebell training. Although kettlebells have been in use for several hundred years, having originated in Russia in the 18th century, it is only relatively recently that they have crossed into mainstream personal training programmes.
Training programmes involving kettlebells can deliver an extensive and impressive range of fitness and performance benefits including cardiovascular improvements, muscle stabilisation, improved back health function and rehabilitation benefits.
A study funded by the American Council on Exercise (Schnettler et al., 2010 ) analysed the energy cost and exercise intensity of kettlebell workouts for ten subjects aged between 29 and 46.
A five minute kettlebell snatch test was completed by all subjects. The rate at which subjects had to perform snatches increased from the first to fifth minute culminating in the fifth and final minute when subjects went all out, performing as many snatches as they could.
Heart rate and oxygen consumption were measured throughout the five minutes. A peak RPE (Rate of Perceived Exertion) was taken following the test, as were blood lactate levels.
Subjects then completed a 20 minute kettlebell interval training programme with 15 seconds of snatches on their dominant hand, then 15 seconds of rest followed by the same with their other hand. Heart rate and blood lactate levels were recorded.
The researchers found the average calorie burn for the 20 minutes was 404 calories. Lead researcher John Porcari explained ‘they were burning at least 20.2 calories per minute which is off the charts…equivalent to running a six-minute mile pace.’
The above study provides evidence that kettlebell training is a hugely effective way to maximise calorie burn. The average heart rate was 93% of maximum during the kettlebell snatch workout. This clearly shows that the cardiovascular benefit of kettlebell training can be immense.
However, kettlebells aren’t alone in delivering such dramatic results. In terms of calorie burn at the same effort, Hulsey et al. (2012)  noted that ‘during treadmill and kettlebell exercises matched for RPE, subjects are likely to have a higher oxygen consumption, work at a higher MET level and burn more calories per minute during treadmill running than during kettlebell swings’.
The research findings of Farrer, Mayhew and Koch (2010)  were found to be very similar to the American Council on Exercise funded study (Schnettler et al., 2010). “Kettlebells can provide one heck of a workout. Based on comparisons with data from previous research on standard weight training, the HR and V̇O2 responses during the kettlebell snatch routine suggest it provides a much higher-intensity workout than standard weight training routines.”
Farrar, Mayhew and Koch (2010) found that ‘continuous kettlebell swings can impart a metabolic challenge of sufficient intensity to increase V̇O2max’, continuing to report that ‘kettlebells provide a useful tool with which coaches may improve the cardiorespiratory fitness of their athletes. Their findings are supported by Hulsey et al who found that kettlebell drills can produce increases in aerobic capacity.
The well documented benefit of improving cardiovascular and cardiorespiratory fitness are just two of the many advantages of kettlebell training. A recent research paper has shown the positive impact on stabilising muscles. Jay et al. (2013)  found that kettlebell training improves postural reactions to sudden perturbation as three kettlebell swing workouts per week for 8 weeks significantly decreased stopping time after perturbation. More research is required to ascertain just how far this benefit goes to reduce the risk of spinal injury and maximise sporting performance.
Improved Back Health And Function
Current data also suggests that kettlebells may be an effective alternative tool to improve performance in weightlifting and powerlifting (Manocchia, 2013) .
In a study last year (McGill et al., 2012) unique lumbar loading patterns were identified including approximately 3,200N of lower back compression. Activation – relaxation cycles of substantial magnitude involved MVC (Maximum Voluntary Contraction) of 80% for the gluteals with just a 16Kg kettlebell. The amount of gluteal activation is also impressive. It has been hypothesised that this form of soft tissue loading, which causes abdominal muscular pulses together with muscle bracing, enhances back health and function although concerns have also been raised that that it may irritate tissues.
It appears obvious that kettlebell swings can considerably improve core stability and build back health. However, kettlebell training places unusual and unique demands on the spine and hips and should be avoided for those with structural abnormalities of the spine. We must also introduce kettlebell lifts very gradually into a client’s workout in order for them to gain strength in the required muscles and progress to a more advanced workout.
Another study (Zebis et al., 2012 ) , looking at rehabilitation implications demonstrated how effectively different parts of the hamstring can be targeted to reduce the risk of knee injuries. The kettlebell swing has been identified as a very effective tool for therapists to use when needing to activate semitendinosus over biceps femoris.
The kettlebell is a great tool that has been scientifically proven over the years to offer many health, fitness and performance benefits. It is also a versatile piece of kit that allows the fitness professional to deliver a fun and varied exercise session. In summary, we can safely say that a kettlebell could be a great investment if you want to achieve the following:
Increased aerobic fitness
Improved core stability
High calorie expenditure
Posterior kinetic chain activation
Improved muscular strength and endurance
Improved body composition
Schnettler C, Porcari JP, Foster C, Anders M., 2010. Kettlebells: Twice the results in half the time. ACE Fitness Matters pp 6-10.
Lake, J., Lauder M., 2012. Mechanical demands of kettlebell swing exercise. Journal of Strength and Conditioning Research 26, no. 12: 3209-3216.
Lake, J., Lauder, M., 2012. Kettlebell swing training improves maximal and explosive strength. Journal of Strength and Conditioning Research 26, no. 8: 2228-2233.
Hulsey, C.R., et al. 2012. Comparison of kettlebell swings and treadmill running at equivalent rating of perceived exertion values. Journal of Strength and Conditioning Research, 26 (5), 1203–07.
Farrar, R., Mayhew, J., Koch, A., 2010. Journal of Strength & Conditioning Research: Volume 24 - Issue 4 - pp 1034-1036.
Jay, K., Jakobsen, M., Sundstrup, E., Skotte, J., Jørgensen, M., Andersen, C., Pedersen M., Andersen, L., 2013. Effects of Kettlebell Training on Postural Coordination and Jump Performance: A Randomized Controlled Trial. Journal of Strength & Conditioning Research. 27(5):1202-1209.
Manocchia, P.; Spierer, D.; Lufkin,A.; Minichiello, J.; Castro, J., 2013. Transference of Kettlebell Training to Strength, Power, and Endurance, Journal of Strength & Conditioning Research. 27(2):477-484.
McGill, S., Marshall, L., 2012. Kettlebell swing, snatch, and bottoms-up carry: Back and hip muscle activation, motion, and low back loads. J Strength Cond Res 26(1): 16–27.
Zebis M., Skotte J., Andersen C., Mortensen P., Petersen M., Viskær T., Jensen T., Bencke J., Andersen L., 2012. Kettlebell swing targets semitendinosus and supine leg curl targets biceps femoris: an EMG study with rehabilitation implications.