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The Kinetic Chain Of Golf And The “Missing Link”
In all sports, the distance a ball can realize is directly dependent on speed. Speed relates to the various body segments that exert their individual and collective forces on their end point which reaches the ball. That end point, in the case of golf, is the clubhead at impact. Power, height and ground reactive forces, including torque, are all important factors in achieving maximum distance as well. Golf is a triplanar sport involving transfer of body weight, rotation and many variables in body position.1
Understanding The Kinetic Link Principle In Golf
Much of podiatric biomechanics is applicable to the golf swing. The kinetic link principle, or kinetic chain, describes a chain of events linking body segments to one another and the movement (or lack thereof) of a given body segment affects the segments both proximal and distal to it.2 This concept is most familiar to us when it comes to lack of motion at a given joint. Whether from an arthritic process or a fusion, when one joint is incapable of handling the forces normally attributed to it, motion and force then translates to an adjacent joint.
Also known as proximal-to-distal sequencing, kinematic sequence is the specific order in which various body segments act during an action.3 During gait, the subtalar joint pronates at heel contact and sets the stage for the remaining body parts to effectively produce linear gait through a series of motions and muscle accelerations and decelerations. In golf, each distal segment initiates its motion at the time of the maximum speed of the proximal segment, resulting in larger endpoint speeds than the proximal segment.2 The acceleration of one segment is dependent on the deceleration of the more proximal segment, including the club itself. The torso, so important in the golf swing, is dependent on the forces produced by the lower extremities. It then translates force to the upper extremities and eventually into the club and ultimately the club head. In the end, maximum acceleration with the highest velocity possible results if all body segments work efficiently. Research demonstrates this proximal-to-distal sequencing by examining the linear speeds of segment endpoints, joint angular velocities and resultant joint movements.2
A Closer Look At Swing Power And Rotation
As with any weight bearing activity, energy begins from the ground up and requires coordination of movements. Golf professionals stress that an efficient swing requires that each muscle fire and generate force with precise timing to generate and transfer energy to each subsequent body segment in the chain.4 This is especially true during the downswing, when control of the golf club become essential. Timing becomes as important as sequence of acceleration and deceleration so that the club arrives at impact accurately and with maximal speed. Golf instructors tell their students that the swing is not supposed to originate from the arms, instead, swing power should be from the ground up. The most efficient sequence of motion of body segments during the downswing is pelvis and hip movement and power first, followed by the trunk, with forces translated to the arms and finally into the club.5 The pelvis, of course, depends on the lower extremities. The backswing sequence, for the record, is the opposite; the club first, followed by the arms, chest and then hips.4
Rotation is a critical component of achieving maximum torque and clubhead speed at impact. Movement around each body part’s long axis can produce accumulated forces on multiple planes. In addition to speed, I often see rotation emphasized in reference to power, form and injury prevention. Most golf articles, videos and instructors I’ve reviewed focus on rotation of the torso from both the hip and thoracic spine rotation. Many of these biomechanical and instructional pieces focus on back injuries related to lack of rotation.6 It is common for instructors to focus their instruction on how to use the large muscle groups (including the gluteus maximus when discussing the lower extremities) to develop rotational power during the backswing and downswing.5,7
The Role Of The Hip, Pelvis And Thoracic Spine In Golf Biomechanics
The hips and pelvis are essential in golf and other sports due to the size of the bone structure and the amount of force needed to generate power.4 In sports that involve an overhead throwing motion, studies show the hip and trunk areas contribute approximately 50 percent of the kinetic energy and force.2 In golf literature, articles commonly discuss the most powerful way to translate weight from the back (trail) foot to the front (lead) foot. In my experience, most golf professionals will attempt to have their students rotate through the hips as opposed to translating weight in a directly lateral motion. If someone is unable to rotate the hips, this minimizes the force and power generated in the pelvis, which results in increased stress in distal segments2 similar to what we find with a fused joint in the foot. Biomechanical studies on golf lag significantly, especially regarding the lower extremities versus the upper extremities.1 I have observed that positioning of the pelvis (pelvic tilt) during both the backswing and downswing is thought to have an effect on range of motion of the hips but I was unable to locate any specific studies confirming a direct correlation.
The next body segment in the kinetic sequence of golf is the trunk or thoracic region. As the hips decelerate, acceleration of the trunk begins. Often, injury to the back can be prevented by controlling the rotation relationship of these two segments. The trunk should rotate more than the hips during the backswing to generate higher clubhead speeds at impact.6 Increasing thoracic rotation relative to pelvic rotation preloads the trunk muscles by accentuating their length and allowing them to use the energy stored in their elastic elements to produce more power.6
Much of the golf literature I have read implies that lower back injury is due to either weak stabilizing musculature or lack of rotation of either the hips or the thoracic spine. It seems the articles written by golf instructors, chiropractors and personal trainers focus on stretching to relax muscles, strengthen muscles or mobilizing those specific joints. As with other body segments, the rotation of the thoracic spine must have some dependency on position and by slightly increasing spinal extension (the often recommended set up position for golf), rotation on the backswing increases. In my estimation, this may be due to the more relaxed position of the latissimus dorsi, which would allow increased range of motion of the thoracic spine. I have had a difficult time finding any article that referred to thoracic, lumbar or sacral positioning influencing range of motion of either the thoracic spine or the hips.
The thoracic spine is responsible for providing the rotation of the trunk, which will ultimately translate power to the upper extremities. Golf instructors often refer to pronation and supination in the upper extremities, however, this is not a focus of this article. Few, though, talk about rotation of the lower body. In my experience, it is even more difficult to find any articles or videos specifically addressing rotation of the subtalar joint in golf.
The Feet Are The Foundation Of The Swing: Is The Subtalar Joint “The Missing Link?”
Ground reactive forces, torque, weight transfer and foot position are just a few of the golf principals that show the importance the feet play. There are few studies that specifically show the muscle function of the lower extremities in the golf swing. In 2012, a review of the studies to date found these studies lacking and focused only on the muscles acting on the hip and knee joints.8 However, the feet seem to receive the least amount of attention in the literature and in the biomechanical research in the world of golf, despite affecting balance, stability, foundational support for the body and allowing for range of motion through the kinetic chain.1
Positional angles of body parts (meaning joint positions) are common points of discussion for maximum power of the swing, but I have yet to find a scholarly article that discusses the position of the subtalar joint. A fairly recent (2017) review of reports studying the correlations and causative effects on hip range of motion9 failed to consider the foot despite the insistence of the industry that the swing starts from the ground up. Instructors and those involved in the mechanics of the golf swing understand that golf requires complex rotation or coiling motion of the foot.
Golf instructors debate the position of the foot when addressing the ball – positioning the feet straight or “flared out.” The abducted foot places the subtalar joint in a pronated position and at the same time externally rotates the tibia. Instructors need to understand this affects both available subtalar joint motion and hip rotation. Not allowing the trail hip to fully rotate on the backswing will have as much of a negative impact on the swing as the decreased ability of that same leg to pronate in the downswing.1,10
Whether to place one’s weight forward to the midfoot or forefoot versus weight on the rearfoot is a common point of direction instructors give in regard to address position. The commonly held reasoning is for balancing center of mass, controlling club path and to maximize ground reactive forces.1 I would argue that the important factor here is offloading the subtalar joint to allow for more rotation. In my experience, easing restrictions on the rearfoot allows for increased supination and hip rotation on the backswing. This, along with spine position to maximize thoracic rotation, will give a golfer optimal power from the backswing.
Upon downswing, driving the weight bearing force into the trail heel will maximize ground reactive forces, adjust the club path and allow the needed pronation. On the downswing, having slightly more weight on the lead midfoot allows for seamless transfer of weight to the lateral lead foot to prepare for the stability needed for the remainder of the swing. Finally, in my experience, offloading the trail foot rearfoot during follow-through allows the needed hip rotation along with plantarflexion of both the first ray and ankle joint needed for the finish.
Kelvin Miyahira is one of the world’s leading anatomical researchers of the golf swing. He has a thorough understanding of the human body and analyzes the golf swing from a qualitative biomechanical perspective - except for the biomechanics of the foot. While describing what he began to visualize on the trail foot, Miyahira explained it to others as an extra “lateral wiggle” motion the foot makes in some golfers. At the time, he felt this was in opposition to “biomechanical science’s view is that one should drive with the legs.”11 In reality, his description of this “wiggle” was consistent with the momentum of continuing subtalar joint supination for stability prior to initiating the downswing.
In later personal conversations I had with Kelvin, the concept of STJ supination was more recognized, but the idea of locking the subtalar joint for stability was new to him. As recent as 2017, he thought whether or not to supinate the subtalar joint was a controversial teaching element of golf instructors across the country where some instructors advocate to their students to “keep the weight on the inside of their right (trail) foot.”12
Final Thoughts
As podiatrists, not only do we understand the need for the subtalar joint to supinate to allow for stability prior to the downswing; we can appreciate the influences each lower extremity joint and anatomical or pathological variation might have on the golf swing. When talking about the golf swing starting from the ground up, we clearly know this begins with the foot and the subtalar joint and not the pelvis. As golf biomechanics continues to evolve, the kinetic sequence “missing link” of the subtalar joint is sure to eventually be better appreciated by the golf community.
Dr. Reid is a delegate to the American Podiatric Medical Association and the current Secretary-Treasurer of the Federation of Podiatric Medical Boards. She is a Past President of the Illinois Podiatric Medical Association and the American Association for Women Podiatrists. Dr. Reid is a Fellow of the American College of Foot and Ankle Surgeons and a Distinguished Fellow of the National Academy of Practitioners. She is in private practice in Naperville, Ill.
1. Reid M. Essential keys to diagnosing and treating lower extremity golf injuries. Podiatry Today. 2018;31(4):26-34.
2. Ellenbecker TS, Aoki R. Step by step guide to understanding the kinetic chain concept in the overhead athlete. Curr Rev Musculoskelet Med. 2020;13(2):155–163.
3. Cheetham P. Basic biomechanics for golf. Selected topics. Available at: https://www. philcheetham.com/media/Basic-Biomechanics-for-Golf-Selected-Topics-by-Phil- Cheetham-2014.pdf . Published August 2014. Accessed July 6, 2021.
4. Lower body in the golf swing: step into some speed. Available at: https://rotaryswing. com/golf-instruction/golfbiomechanics/ golf-swing-sequencing-drill . Published February 17, 2014. Accessed July 7, 2021.
5. Cole MH, Grimshaw PN. The biomechanics of the modern golf swing: implications for lower back injuries. Sports Med. 2016;46(3):339–351.
6. Phillips D. What are the key muscles in golf swing? Available at: https://www.mytpi. com/en/articles/fitness/what_are_the_ key_muscles_in_the_golf_swing?page=2 . Published January 13, 2014. Accessed July 7, 2021.
7. Cheetham P. The linear kinematic sequence. Available at: https://www.mytpi.com/articles/biomechanics/the_linear_kinematic_ sequence . Published March 17, 2014. Accessed July 13, 2021.
8. Marta S, Silva L, Castro MA, Pezarat-Correia P, Cabri J. Electromyography variables during the golf swing: a literature review. J Electromyog Kinesiol. 2012;22(6):803-813.
9. Hume PA, Keogh J. Movement analysis of the golf swing. In: Müller B, Wolf S. (eds) Handbook of Human Motion. Switzerland; Springer Nature:2017.
10. Phillips D. The position of the right foot. Available at: https://www.mytpi.com/articles/swing/the_position_of_the_right_foot . Published November 14, 2012. Accessed July 6, 2021.
11. Miyahira K. Revising the kinetic link. Kevin Miyahira Golf. Available at: http:// kelvinmiyahiragolf-articles.com/index. php/articles/articles-2/2010-articles/53- 2010-03-revisiting-the-kinetic-link . Published March 2010. Accessed July 6, 2021.
12. Personal communication with Kelvin Miyahira.
Additional Reference
13. Lattanza L, Gray GW, Kantner RM. Closed versus open kinematic chain measurements of subtalar joint eversion: implications for clinical practice. J Orthop Sports Phys Ther. 1988;9(9):310-314.
