There has been a lot of discussion and controversy in the tennis world lately over the need to adjust technique in accordance with front or cross eye dominance. Notably high profile coach, Patrick Mouratoglou has been outspoken on this topic and is an advocate of learning and modifying techniques based upon this technique.
Specificity, Patrick has spoken about the need to adapt a stance of "open" or "closed" based on eye dominance with the idea that getting the dominant eye closer to the ball will help you watch it better. It's interesting that so many coaches like Patrick anecdotally support the benefit of adjusting open and closed stance techniques to accommodate the dominant eye when the studies on this topic are not high quality and have conflicting/inconclusive findings. I would like to see more scientific support in this area and I try to keep an open mind about this topic, but I think it's worthwhile to examine the well supported, existing science to discuss how eye dominance might impact technique and player performance.
Now here is where this topic gets interesting but also really, really complex. While we might not rotate our bodies differently because of cross eye dominance we can tilt our head differently to accommodate eye dominance differences.
The great Roger Federer is a great example of this technique. Here is an explanation and please be warned it is not easy to explain without a lot of science jargon. Let's start by understanding some basic bodily functions starting with the spine and working our way to the neck and head. Since the function of the cervical spine is to stabilize and maintain the head in a position that allows our eyes to be parallel to the ground. what we see in Roger is cervical flexion and extension. This position and this function is crucial for the "vestibular function", which is the system which assists in balance. This cervical flexion and extension allows Roger to make large movements to scan his surroundings so he can adjust to interact with the environment in this case, the ball. This also aids in swallowing and helps to elevate the rib cage during inhalation.
The bottom line here is that his head tilt (cervical flexion/extension) is the result of his inner ear detecting head rotation( Angular acceleration) and linear motion and then adjusting by seeking a position that allows his eyes to be parallel to the ground while tracking the ball which greatly aids in his balance and breathing. His cerebellum, which is the part of the brain that controls balance is going to fine tune his head position to account for visual acuity differences in each eye. So if he is left eye dominant his head will tend to tilt naturally to accommodate this dominance because it is seeking visual parallel balance. In some studies it was found that this process is mostly controlled by several autonomic receptors that actually help build nerve pathways to ingrain this response.
So there it is. Almost all of us have a "dominant" eye and while we may not be born with it, dominance usually develops. As most of us are not as gifted to naturally adjust as well as Roger we can actively tilt our heads to help us balance better to accommodate eye dominance and see vast improvements in our game. Before undertaking such a tilt I think it's advisable to do a simple test to see which is your dominant eye. I wont describe it here but many YouTube videos make it very easy to do.
Again, I know this article is highly technical. It is aimed to help coaches as much as players to understand the science behind this topic at a little higher resolution.
Steven Kaplan is the owner and managing director of Bethpage Park Tennis Center, as well as director emeritus of Lacoste Academy for New York City Parks Foundation and executive director and founder of Serve & Return Inc. Steve has coached more than 1,100 nationally-ranked junior players, 16 New York State high school champions, two NCAA Division 1 Singles Champions, and numerous highly-ranked touring professionals. Many of the students Steve has closely mentored have gone to achieve great success as prominent members of the New York financial community, and in other prestigious professions. In 2017, Steve was awarded the Hy Zausner Lifetime Achievement Award by the USTA. He may be reached by e-mail at StevenJKaplan@aol.com.