By Thomas Fahey, EdD
Single-handedly, Pavel Tsatsouline, a former physical training instructor for the Soviet Special Forces and a nationally ranked kettlebell competitor in the former Soviet Union, popularized kettlebell training in the United States. He elevated it from an obscure, quaint training method of ancient athletes to a wildly popular form of exercise that has applications for people ranging from elite athletes to elderly people in nursing homes (see www.dragondoor.com).
Most modern health clubs contain scores of expensive exercise equipment that isolate specific muscle groups in the arms, shoulders, thighs and abdomen. While isolation training has some applicability to bodybuilders, it does not develop functional fitness that can be used in sports or the activities of daily life. Most kettlebell exercises work the body in a very dynamic way that link and coordinate large muscle contractions and promote smooth, powerful movements. While there are countless varieties of kettlebell exercises, the swing, one-arm snatch and one-arm clean and press are central to most kettlebell training programs.
The Science Behind Kettlebell Training
Scientists in the former Soviet Union studied kettlebell training extensively, and we are beginning to see research in the West. Kettlebell training is highly ballistic, which means that many exercises involve fast speed, pendulum-type motions, extreme decelerations and high-speed eccentric muscle contractions.
During concentric or shortening contractions, the muscles exert less force as contraction speed increases. The opposite is true during eccentric or lengthening contractions— the muscles exert more force the faster they lengthen. Kettlebell swings require dynamic concentric muscle contractions during the upward phase of the exercise followed by high-speed eccentric contractions to control the movement during the return to the starting position.
Dr. Stuart McGill, from Waterloo University in Canada, performed electromyography (EMG) measurements on Pavel during one- and two-arm kettlebells swings. EMG measures the electrical activity in muscles and can predict muscle activation levels during specific movements and exercises. The lats and core muscles showed higher activation levels during the downward part of the swings when the major muscle groups were contracting eccentrically compared to the upward part of the swings when they were contracting concentrically.
Several recent studies showed the value of high-speed eccentric training for building muscle mass and strength. Canadian researchers, led by Tim Shepstone, found that high-speed eccentric training increased muscle cross-sectional area and the size of fast-twitch motor units (muscle fibers and their nerve) better than slow-speed eccentric training. High-speed contractions caused greater disruption at the cell level, which resulted in greater adaptations (i.e., more protein synthesis) in muscle mass and strength. Likewise, a Brazilian study of older men (60-76 years old) showed that high-speed training resulted in greater strength gains than traditional, controlled-speed weight training. Neither of these studies used kettlebells, but the results showed the value of high-speed ballistic training.
We are beginning to understand the physiology behind high-speed eccentric training. These exercises create high levels of metabolic stress that trigger cell damage and stimulates protein synthesis, which results in gains in muscle mass and strength. Kettlebell exercises, such as swings and snatches, stress the cells and tissues for prolonged periods (15 seconds to several minutes) that cause cell inflammation and promote increases in muscle mass and strength.
Kettlebells swings, cleans, and snatches are unsurpassed for developing the hip movements that are vital in exercises like the squat, pulling exercises such as the clean and snatch; and athletic movements, such as jumping, sprinting and throwing. It is much easier to maintain a healthy and stable spine position during kettlebell swings than when lifting a barbell from the floor or doing back squats. The kettlebell swing movement makes it possible to do more of these hip hinges (hip drives) without putting the spine at risk.