Kettlebells vs. Free Weights: Which Is Better?
Training with a kettlebell, a large iron ball connected to a handle, may seem like a relatively new way to exercise – but there is nothing new about kettlebells. 19th century strongmen such as Arthur Saxon, Eugene Sandow and Ivan Poddubny used kettlebell to build lean, powerful, lightning-fast physiques that allowed them to perform incredible feats of strength and athleticism. Russian athletes and soldiers have used kettlebells as part of their training for more than 300 years.
On the surface, kettlebells don’t look much different than standard dumbbells. They have a handle connected to a weight just like dumbbells and they come in a variety of sizes, but that’s where the similarity ends. The kettlebell weight is located at the end of the handle instead of on either side of it. Also, the design of the kettlebell allows you to do high-speed ballistic exercises with a pendulum-like action. Many kettlebell exercises such as swings, snatches and cleans, require high-speed eccentric muscle contractions, which produce surprisingly high muscle forces. High-speed eccentric training develops whole-body fitness rapidly, with little or no muscle soreness.
I know, I know – you’ve heard it before. Like variable resistance weight machines, step aerobics, yoga and spinning, some people get so excited about the latest exercise technique that they think it does everything under the sun. Kettlebell training is not the end-all substitute for traditional resistive exercise. However, almost any exercise you can do with free weights and machines, you can do with kettlebells. They are terrific training tools that build strength, power, muscle endurance and aerobic capacity, while promoting fat loss. They also offer a training stimulus (i.e., high-speed ballistic and eccentric training) not offered by other forms of exercise.
Going to the Source: Pavel Tsatsouline
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).
As a lifelong competitor in the discus throw, former powerlifter and exercise physiology professor, I am no stranger to lifting weights and strength training methods. Like most Americans, however, I had little experience with kettlebells. Pavel invited me to attend a three-day kettlebell instructor’s workshop at the football-training compound at San Jose State University in California. A few weeks later, Pavel and I discussed the science behind kettlebell training.
Most modern gyms 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 developing an impressive looking physique, 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. Below is a brief description of these exercises.
The kettlebell swing is the keystone in kettlebell training routines. The exercise appears simple, but requires coordinated, linked contractions of the thigh, butt, core and upper body muscles to do it properly. Stand a foot or so behind the kettlebell, sit back and grasp the handle with both hands. With the weight on your heels, swing the kettlebell backward so that it pendulates (rocks back) fairly close to your groin. Drive the hips forward and contract the quads, glutes, pelvic floor and abdominal muscles, which causes a rapid acceleration of the kettlebell upwards to shoulder-level. Exhaled sharply (but not fully) at the top of the swing to accentuate the bracing motions of the major muscles in the body. Keeping the spine in an upright neutral position (i.e., maintaining the natural spinal curves), let the kettlebell accelerate downward as you flex your hips, bend your knees and maintain straight arms. Perform 10-20 repetitions of this exercise. As skill increases, do the swings one arm at a time.
As you hone your one-arm swing skills, you are ready to graduate to the one-arm snatch. The snatch involves raising the kettlebell overhead in one continuous motion. Pick up the kettlebell, swing it back between your legs and snatch the kettlebell overhead in one uninterrupted motion to a straight-arm lockout, with your arm close to your head. During the upward swing, used the bracing movement created by simultaneously contracting the quads, glutes, pelvic floor and abdominal muscles to propel the kettlebell upward. Stop momentarily with the arms and legs straight and the feet and body stationery. Lower the kettlebell between your legs with one loose, uninterrupted motion without touching the chest or the shoulder and repeat the motion again. Snatch the kettlebell first with one arm and then the other.
The clean and press is another popular kettlebell exercise for athletes and people interested in general fitness. Grasp the handle using a pistol grip (handle perpendicular to the body) and do not bend at the wrist. Lift and swing the kettlebell backward, with hips flexed, knees bent and spine upright (maintaining natural spinal curves). Keeping the elbow close to the body, drive the hips forward and contract the quadriceps, glutes, pelvic floor and abdominal muscles to initiate an upward movement of the kettlebell. Cheat curl the kettlebell to shoulder level as you snap your hips at the top of the movement. Pause in the clean (rack) position, with quads contracted and spine in a neutral position. Keeping your shoulders down, press the kettlebell overhead and lock out your elbow completely. Lower the kettlebell to your chest and then swing it between your legs as described previously (maintaining a neutral spine) and repeat the exercise.
Learn the motions properly from an RKC-certified instructor. You can cause severe spinal and shoulder injuries if you do these exercises improperly. Most people who try kettlebells without instruction initiate the movements with the arms and shoulders and cause excessive stress to the spine. Doing the exercises correctly will stabilize the spine and help develop healthy and pain-free shoulders and back.
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 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 lean body 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.
The Case for Traditional Weight Training
Very little objective research exists on kettlebell training. While empirical observations suggest that kettlebell training causes rapid increases in strength, power, dynamic flexibility, joint stability, muscle endurance and aerobic capacity, we need well-designed evidence-based research to support them.
Increases in muscle hypertrophy and strength from training depend on muscle tension and time under tension. Traditional weight-training exercises, such as bench presses, back squats, deadlifts and cleans, increase the capacity to create high concentric and eccentric muscle contraction forces (i.e., shortening contractions) that don’t typically occur during kettlebell training.
Why argue about which type of training is best when you can do both? Athletes and people interested in general fitness can use a combination of kettlebells and traditional weight training, even exercises that use machines. All provide overload that can increase strength and power. However, kettlebells make it possible to do high-speed ballistic motions that appear to transfer rapidly to sports movements and the activities of daily life. They are a valuable addition to your training arsenal.
Bottaro M, N Samyra, N Machado, W Nogueira, R Scales and J Veloso. Effect of high- versus low-velocity resistance training on muscular Fitness and functional performance in older men. Eur J Appl Physiol, 99:257-264, 2007
Colliander EB and PA Tesch. Responses to eccentric and concentric resistance training in females and males. Acta Physiol Scand, 141:149-156, 1991.
Cronin JB, PJ McNair and RN Marshall. Force-velocity analysis of strength-training techniques and load: Implications for training strategy and research. J Strength Cond Res, 17:148-155, 2003.
De Vos NJ, NA Singh, DA Ross, TM Stavrinos, R Orr and MA Fiatarone Singh. Optimal load for increasing muscle power during explosive resistance training in older adults. J Gerontol A Biol Sci Med Sci, 60:638-647, 2005.
Paavolainen L, K Hakkinen, I Hamalainen, A Nummela and H Rusko. Explosive-strength training improves 5-km running time by improving running economy and muscle power. J Appl Physiol, 86:1527-1533, 1999.
Sale DG, AR Upton, AJ McComas and JD MacDougall. Neuromuscular function in weight-trainers. Exp Neurol, 82:521-531, 1983.
Seger JY and A Thorstensson. Effects of eccentric versus concentric training on thigh muscle strength and EMG. Int J Sports Med, 26:45-52, 2005.
Shepstone TN, JE Tang, S Dallaire, MD Schuenke, RS Staron and SM Phillips. Short-term high- vs. low-velocity isokinetic lengthening training results in greater hypertrophy of the elbow flexors in young men. J Appl Physiol, 98: 1768–1776, 2005.
Tsatsouline P. Russian Kettlebell Challenge, Instructors Manual. Minneapolis: Tactical Strength, Inc. and Dragon Door Publications, 2008.
Zehr EP and DG Sale. Ballistic movement: Muscle activation and neuromuscular adaptation. Can J Appl Physiol, 19:363-378, 1994.