The kettlebell is often promoted as an exercise that can be used in metabolic conditioning. In a sense this refers to the benefits of doing cardiovascular exercise without having to do cardio. This is overly simplistic, but it suggests an ability to burn a lot of calories and train specific energy pathways. To this point this has been merely a claim, not anything that has been adequately researched.
Hulsey et al studied this by comparing kettlebell swings to treadmill running. The idea being to see how similar they are in terms of heart rate, calories burned, oxygen consumption, etc. The authors studied 13 subjects with no experience with kettlebells. The subjects participated in two sessions:
- The first involved performing either 16kg kettlebells (men) or 8kg kettlebells (women) and performing swings for 10 minutes with a 35 second on 25 second off rhythm.
- The second session involved performing 10 minutes of treadmill running with the speed adjusted to be as difficult as the subjects perceived the kettlebell swings.
In terms of results:
- Heart rate and rating of perceived exertion increased for both exercise modes as time increased.
- Oxygen consumption was relatively flat for the kettlebell over the 10 minutes, but increased during the 10 minutes for the running.
- In addition, there were statistically significant differences between kettlebells and treadmill running in terms of METS, calories per minute, total calories, and oxygen consumption with the treadmill being between 26 and 38% greater than the kettlebells.
The authors conclude that while the treadmill has a greater training effect (aerobic conditioning), the kettlebell meets ACSM’s criteria for maintaining aerobic fitness. In other words, the kettlebell might be an acceptable tool for days off from running when an endurance athlete wants a training tool to maintain their aerobic conditioning. The kettlebells have the benefit of strength training and more well-rounded development of muscular endurance. However, this study suggests that treadmill running provides more bang for the buck in terms of aerobic conditioning and burning calories.
It needs to be pointed out that kettlebells are not used as an aerobic conditioning tool by most strength and conditioning professionals. They are an excellent way to develop strength, hypertrophy, and power to develop almost all the muscles of the body. They require balance, coordination, and mobility. Kettlebells also require both sides of the body to work independently. In addition, they are also useful for metabolic conditioning that focuses on anaerobic energy pathways (think sprinting). I personally feel that it’s a poor use of an athlete’s time to swing the kettlebell for ten minutes, rather they should be focusing on movements and skills that have some transfer to the sport and on strength training that can develop strength/power that can be used.
Hulsey, C.R., Soto, D.T., Koch, A.J., and Mayhew, J.L. (2012). Comparison of kettlebell swings and treadmill running at equivalent rating of perceived exertion values. Journal of Strength and Conditioning Research, 26(5), 1203-1207.
