In theory lifting a weight is the same regardless of its shape. In practice however anyone who’s had to lift his mum’s biggest garden pot, knows this is not the case. Shape, handles and center of gravity do make a difference in the way the load of the weight is distributed and then the way that load is passed onto muscles and bones when we lift it.

This is why lifting kettlebells is an exercise that’s different to lifting, say dumbbells or a barbell. The questions to ask here then are how and why? This is where science comes in. Lifting a weight, any weight, is an act that involves physics. We need to apply our own force to physically move an object that has mass which, in keeping with Newton’s third law of motion^[1] exerts an opposite and equal force upon us.

In an oversimplification of this complex act we understand that the greater the weight we try to move the greater the load that is applied back to our muscles and bones. This then triggers the adaptive response that changes our muscles and makes us stronger. This is where it now gets interesting. Because we are not a perfect geometric shape the force that is applied back to us depends on a multitude of factors such as the exact type of muscle activation that takes place, the spinal loading that this entails, the lumbar rotation that may or may not take place as a result, the ground force reaction that results from the lifting of the weight and the transfer of the horizontal force.

If all this still sounds complicated it is because it is. But it doesn’t require a lot of complexity to understand that the shape of the kettlebell and its unique movement, in our grip, during lifting changes the angle at which it is held. This, in turn, changes both the angle of the joints during the act of lifting a kettlebell and the direction of the force applied to the muscles and bones. The force that the muscles can exert as well as the reaction force that is applied to them is very much dependent on the angle of the joint during which flexion takes place.

For example, a 2017 study^[2] that looked at how standing on the balls of the feet and doing calf raises affects the muscles and tendons showed that ankle strength gains were more measurable when the foot was extended backwards because that significantly changed the angle of the ankle joint and the forces sustained by it.

Similarly, another study published in the Journal of Physical Education and Science^[3] that looked at how the quads and calves behave during knee joint extensions concluded that from “a biomechanical perspective, changes in a joint angle occur due to the contraction of the surrounding joint muscles, changes in the joint angle of a lever arm length, and the length of the muscle. Changes in muscle length according to the angle change in the joint causes a change in the force generated in the muscles. In addition, according to these joint angle changes, muscle activity changes.”

This was in keeping with much older studies^[4] that showed that the angle of the joint played a key role in the amount of muscle force that can be brought to bear and how much muscle activation could be achieved as a result.^[5]

Kettlebell Training Results

All of this shows that because of their unique shape and ergonomic grip that shifts the applied force of the weight with the motion of the body so that it travels in line with muscles and bones, kettlebell exercises apply a more ergonomic load to the body that is entirely in keeping with what the body is naturally designed to do.

As a result kettlebell exercises are unique for use in stable and unstable surfaces^[6] and can be used for rehabilitation after injury^[7] in both upper body^[8] and lower body cases^[9] they can also be used to combat poor bone strength.^[10]

The benefits of kettlebell training come with a trade-off however. A 2012 study published in the Journal of Strength and Conditioning^[11] showed that when pure strength gains are the goal, traditional weightlifting exercises using dumbbells and barbells delivers strength gains, faster. The ability of kettlebell exercises to recruit a wider number of muscle groups and tendons and help develop joint stability is evidenced by yet another study carried out in 2013^[12] and published in the Journal of Strength and Conditioning that showed that test subjects who trained with ketllebells for ten weeks then showed faster gains in strength and endurance when they returned to normal weight training.

A 2015 review study published in the Physical Therapy Reviews^[13] further backed up the ability of kettlebell training to enhance functional strength and power. The study reviewed the results of five different studies that looked at subjects of different age, sex and ability who underwent kettlebell training routines. The reviewers agreed that kettlebell training, in every instance, helps develop greater power and strength. It does not, however, improve aerobic performance.

Conclusions

Kettlebell training delivers benefits that traditional weight-lifting methods either don’t or cannot deliver as fast:

• Greater joint stability
• More muscle recruitment
• An increase in functional strength
• Rehabilitative qualities in joint injuries
• An increase in physical power, especially when coupled with traditional weight training

Our kettlebell workouts allow you to find to try kettlebells out if you haven’t trained with them before. Our Kettlebell Program can help you recover from any minor joint instability issues and can help you take your physical performance to a new level, especially when you return to more traditional training programs and workouts afterwards.

Research

1. Newton's Third Law of Motion.
2. Fukutani Atsuki, Misaki Jun, Isaka Tadao. Influence of Joint Angle on Residual Force Enhancement in Human Plantar Flexors. Frontiers in Physiology, Vol. 8., 2017, pp 234. Doi: 10.3389/fphys.2017.00234. ISSN: 1664-042X.
3. Ha M, Han D. The relationship between knee joint angle and knee flexor and extensor muscle strength. J Phys Ther Sci. 2017;29(4):662-664. doi:10.1589/jpts.29.662
4. Marginson, Vicky & Eston, Roger. (2001). The relationship between torque and joint angle during knee extension in boys and men. Journal of sports sciences. 19. 875-80. 10.1080/026404101753113822.
5. Macisaac, Dawn & Duffley, C. & Parker, Philip & Englehart, Kevin & Scott, R.N.. (2001). The effects of force and joint angle on muscle conduction velocity estimation. 2. 1055 - 1057 vol.2. 10.1109/IEMBS.2001.1020370.
6. Silva, R., Amaro, N., Marinho, D., Amado, S., & Morouço, P. (2017 Kinematic analysis of kettlebell swing in different surfaces–comparision between stable and unstable surfaces.
7. Brumitt J, En Gilpin H, Brunette M, Meira EP. Incorporating kettlebells into a lower extremity sports rehabilitation program. N Am J Sports Phys Ther. 2010;5(4):257-265.
8. Başkurt, Zeliha & Başkurt, Ferdi & Gelecek, Nihal & Özkan, Mustafa. (2011). The effectiveness of scapular stabilization exercise in the patients with subacromial impingement syndrome. Journal of back and musculoskeletal rehabilitation. 24. 173-9. 10.3233/BMR-2011-0291.
9. van Middelkoop M, Rubinstein SM, Verhagen AP, Ostelo RW, Koes BW, van Tulder MW. Exercise therapy for chronic nonspecific low-back pain. Best Pract Res Clin Rheumatol. 2010 Apr;24(2):193-204. doi: 10.1016/j.berh.2010.01.002. PMID: 20227641.
10. Martyn-St James M, Carroll S. A meta-analysis of impact exercise on postmenopausal bone loss: the case for mixed loading exercise programmes. 2009. In: Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet]. York (UK): Centre for Reviews and Dissemination (UK); 1995-. 
11. Otto, William & Coburn, Jared & Brown, Lee & Spiering, Barry. (2012). Effects of Weightlifting vs. Kettlebell Training on Vertical Jump, Strength, and Body Composition. Journal of strength and conditioning research / National Strength & Conditioning Association. 26. 1199-202. 10.1519/JSC.0b013e31824f233e. 
12. Manocchia, Pasquale1; Spierer, David K.2; Lufkin, Adrienne K. S.1; Minichiello, Jacqueline1; Castro, Jessica1 Transference of Kettlebell Training to Strength, Power, and Endurance, Journal of Strength and Conditioning Research: February 2013 - Volume 27 - Issue 2 - p 477-484. doi: 10.1519/JSC.0b013e31825770fe
13. Joe Girard, Kristina Koenig, Dave Village. (2015) The effect of strength and plyometric training on functional dance performance in elite ballet and modern dancers. Physical Therapy Reviews 20:4, pages 233-240.