Today's strength coaches and personal trainers have a wide variety of modalities at their disposal to help their athletes and clients achieve desired results. Resistance training can be performed with many different modalities, including free weights, machines, resistance tubing, medicine balls, and bodyweight. All these modalities possess certain advantages and disadvantages with respect to achieving an adaptive response. The kettlebell is no different. Their use dates back hundreds of years when they were a popular training implement in various Eastern Block countries for increasing strength, endurance, agility, and balance, as well as challenging both the muscular and the cardiorespiratory systems.
The majority of kettlebell exercises focus on dynamic, total body integration movements rather than muscular or joint isolation. In recent years, the kettlebell has risen in popularity throughout the world. However, there has been limited empirical evidence to support kettlebell use as a training modality. Moreover, because many kettlebell exercises are ballistic in nature, the question arises as to whether or not kettlebell training is effective for increasing muscular strength, muscular endurance, cardiorespiratory endurance, and decreasing body fat.
RESEARCH
Aside from safety, a primary concern of the strength coach or personal trainer should be whether a modality such as the kettlebell has any merit in helping their athletes or clients achieve their training goals. Although there has been a paucity of research to date, several recent studies do suggest a potential role for the use of kettlebells in strength and conditioning protocols.
A search of PubMed revealed just 1 study that directly investigated the effects of kettlebells on muscular strength, power, and endurance. Manocchia et al. (3) recruited 15 subjects (20–72 years of age) with varying levels of exercise experience and evaluated their response to a regimented kettlebell training program. After 10 weeks of biweekly training, significant improvements were seen in bench press strength (51.7 ± 25.0 kg versus 56.4 ± 27.1 kg) and back extension endurance (45 ± 5.7 repetitions versus 54 ± 9.3 repetitions). Moreover, a high degree of transfer was noted in performance of the traditional clean and jerk (30.8 ± 16.7 kg versus 38.5 ± 17.1 kg), indicating that kettlebell training significantly enhances muscular power. Taken as a whole, these results suggest that kettlebells are effective for improving varying components of muscular fitness and are suitable to a wide range of training abilities and demographic groups.
Kettlebells also may be beneficial for improving cardiorespiratory fitness and aiding in weight management. A study by Farrar et al. (1) determined that the heart rate response and oxygen cost of performing the kettlebell swing (Figures 1a and 1b) had a greater impact to the cardiorespiratory system than has been shown with the traditional circuit weight training. Other research suggests that kettlebell training may not be quite so metabolically demanding. Preliminary research by Lanier et al. (2) estimated that the energy cost of kettlebell exercise equates to 4.97 ± 2.02 kcal/min. This is significantly less than barbell training, which has been shown to result in an expenditure of 11.5 kcal/min (4). It should be noted that the training intensity used to determine kettlebell energy expenditure was substantially lower than that used for the barbell protocol. Thus, comparisons between the 2 modalities are difficult to interpret and would seem to be related to the greater training loads employed in barbell exercises. Further research is warranted in this area.
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Figure 1: Two-arm kettlebell swings: backward (a) and forward (b) positions.
Taken as a whole, current evidence seems to indicate that kettlebells have efficacy as a training implement. At the very least, their use helps to interject greater exercise variety into a routine. This can be beneficial in optimizing muscle development (5) and enhancing exercise motivation (6).
IMPLEMENTATION
When implemented properly, kettlebells can be used as an alternative for training movements, such as the squat, deadlift, or clean. Setting up the proper prescription for overload and progression should be the primary goal when introducing kettlebells into a training program. Training protocols for kettlebells do not necessarily need to be different from the traditional resistance training protocols; they are simply the means of the external resistance. Moreover, the concept of specificity should be considered when designing a kettlebell program (e.g., client is not entering a Strongman contest).
As with any training implement, the amount of resistance chosen depends entirely on the strength and skill level of the individual for the particular exercise in question. As a general rule, female rank beginners will start with approximately 8–12 kg for double-handed swings, whereas male rank beginners will start around 12–16 kg. These loads should be adjusted accordingly, depending on the client. Emphasis should be placed on the safety and technique of the movements. Because most kettlebell exercises are compound movements, specific emphasis should be placed on the explosive triple extension at the ankle, knee, and hip joint complexes when performing these exercises. See Table 1 for descriptions and muscles used with some common kettlebell exercises.
Table 1: Kettlebell exercises
CONCLUSIONS
Kettlebells can be a safe and effective exercise modality that enhances a client's training experience. Used properly, kettlebells can help to accelerate fat loss and develop muscular strength, muscular endurance, and cardiorespiratory endurance. Numerous certifying bodies exist that teach proper kettlebell technique, including the Russian Kettlebell Challenge and International Kettlebell and Fitness Federation. It is recommended that the strength coach or trainer consult with one of these organizations for more information on implementing kettlebells into their training programs.
Figure 2: One-arm clean and press: (a) clean with thumb portion pointing towards the body, (b) rack with kettle bell wrapping around the arm press, (c) overhead pressing of the kettlebell.
Figure 3: Goblet squat: (a) start position and (b) end position.
REFERENCES
1. Farrar RE, Mayhew JL, and Koch AJ. Oxygen cost of kettlebell swings.
J Strength Cond Res 24: 1034–1036, 2010.
2. Lanier AB, Bishop E, and Collins MA. Energy cost of a basic kettlebell training protocol.
Med Sci Sports Exerc. 37: S51, 2005.
3. Manocchia P, Spierer DK, Minichiello J, Braut S, Castro J, and Markowitz R. Transference of kettlebell training to traditional Olympic weight lifting and muscular endurance.
J Strength Cond Res 24: 1, 2010.
4. Scala D, McMillan J, Blessing D, Rozenek R, and Stone M. Metabolic cost of a preparatory phase in weightlifting: a practical observation.
J Appl Sports Sci Res 1: 48–52, 1987.
5. Schoenfeld BJ. The mechanisms of muscle hypertrophy and their application to resistance training.
J Strength Cond Res 24: 2857–2872, 2010.
6. Sherwood NE and Jeffery RW. The behavioral determinants of exercise: implications for physical activity interventions.
Annu Rev Nutr 20: 21–44, 2000.
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