What makes this tennis blog different? As an Exercise Physiologist, Biomechanist, and Ergonomics Consultant, my students have learned to ask questions about human performance that most tennis coaches might not get, such as: Why isn’t the United States dominating the men’s and women’s tour anymore? Biomechanically, what makes Federer such a good model for […]
Physical prowess, agility, coordination, and strength have always been the main criteria in judging athletic ability. Most, if not all athletic training programs, have been designed with those criteria in mind, even though our body will only respond to what it can see. Despite this fact, little attention has been paid to vision, which is now the last frontier for those interested in improving their performance on and off the playing field.
This “last frontier” of sports, referred to as Sports Vision (SV), Developmental Optometry, Sports Vision Training (SVT), Vision Training (VT), or Orthoptics, starts with a special eye examination which includes Dynamic Visual Acuity measurements. Regular, “static” eye-exams and the use of corrective lenses are no substitute.
Some of the above name are based on what the training is targeted to do. A child who is improving the ability to track from line to line while reading is practicing Vision Training (VT). A person recovering from eye surgery, trauma, or an acute visual challenge might call this training Orthoptics. This note will focus on an athlete’s SVT.
By undertaking a simple visual training program, ANY athlete can improve performance. That’s because the eye, like the muscles in our bodies, can be strengthened to perform better with exercise. The principle to remember is that no vision skills are passed from our parents. That ALL visual skills are learned!
Q) Who is most known for the best eyes in tennis?
A) Andre Agassi
A list with links to other publications can be found at: USPTAPro.com
(appeared in 2014 Sept/Oct edition of TennisIndustry magazine)
For over 50 years, most tennis courts around the world have been lit with Metal Halide (MH) fixtures, yet few who use them understand their unique qualities. They SEEM to last endlessly, but that’s far from the truth. More importantly, the long reign of MH may be coming to an end in favor of new, much more efficient, “green” technology.
For those new to the lighting industry, a little “Flood Lighting 101” is in order. Metal Halide technology is one member of a family of High Intensity Discharge (HID) lighting systems, which includes street and shopping center lighting.
In HID lighting, electricity heats a metal for several minutes until it vaporizes inside a bulb to give off light, and plenty of heat, which is energy lost. In this case around 8,000 degrees Fahrenheit, which is a lot of lost energy! The next
standard for tennis/sports lighting, will prevent this waste.
As you know, MH bulbs are housed inside a fixture, or “Can”, which has reflectors that focus the light from the back and sides of the bulb downward and outward. It is important to know that MOST current MH light is reflected light from the back and sides of the bulb and not direct light. This makes a difference in its actual and perceived intensity compared to the direct LED lighting you see in office and home lamps.
For a shopping center or highway, the HID metal to be heated is sodium, which comes in two types, Low Pressure Sodium (LPS) or High Pressure Sodium (HPS). Each gives off a “champagne”, yellowish color. LPS and HPS are great for black and white security cameras but not very pleasant for the human eye as it washes out color. This makes people a bit uncomfortable and they do not want to loiter too long in this light. On the other hand, LPS/HPS is VERY efficient, very cheap, and long lasting so it is great for parking lots, alleys, and highways.
For sports, the metal of choice inside the bulb is mercury. Older players might remember the name “Mercury Vapor”. Since mercury gave off a “blue-ish” light, trace amounts of other metals (or halides) were added to help stimulate our eye’s sense of color, so “Metal Halide” was born. MH is also MUCH better for a television camera so prime time sports went “cha-ching”!
The MH Downside
First, experts tell us that MH bulbs lose about 5-10% of their illumination PER YEAR! This is according to Ricc Bieber (Bieber Lighting Consultants) and Greg Moreland (Moreland Lighting LLC). Most lamps we know are either fully on performing near maximum, off, or burned out. But MH is different in that it degrades quickly then levels off for years. Also, most lamps familiar to the public do not require warm up. That 6,000 degrees takes a while!
Why do the experts say ”5-10%”? It’s because a hot MH bulb attracts dust and particulates like the warm computer at your desk
and some environments have more particulates in the air than others. Either way, it’s a significant drop in performance.
(Above) The lighting tech approaches a very cloudy lens. Then he secures a clean bulb and lens. Notice the reflections.
A recent experiment conducted by the author, Bieber Lighting Consultants, and Moreland Lighting LLC confirms this and more. We compared the illumination of old 1000 Watt MH bulbs behind dirty lenses, clean lenses, and new 1000 Watt MH bulbs, all with two types of light meters.
Our results showed that just cleaning the lenses can result in up to 24% more light, and replacing the old bulbs created up to another 40% more light to the court. Plus, it’s smart to do both at once. My vendor charges $105 for the trip, $95 per lamp (for six or more per court), which includes labor.
At that time, all capacitors should be checked and changed if needed and noisy transformers replaced. For an 8 light court, I plan to budget $900 to clean the lenses and replace the bulbs from my vendor. More details on this in Part 2.
Now you know that MH performance drops quickly each year. It flat lines at what lighting experts call “Mean Lumens” which, is around 40% of new bulb capacity. This is despite the fact that it often still ignites and might “appear” to work for many years after that. Here are our MH lighting tips to facility operators and tennis directors:
1) Clean lenses and properly operating MH bulbs SHOULD be uncomfortable to look at directly.
2) Bulbs and lenses can be cleaned but NEVER the reflectors.
3) Budget for MH bulb replacement and lens cleaning at the same time, between 3 to 5 years max.
In Part 2, we will review the hard costs of running MH lights and compare them to their most likely successor. For now, picture MH lighting like 8 hair dryers on full blast at their 1000 Watt setting, with diminishing performance every year, and significant repair costs. There must be something better than that, right?
What if the next technology could save 70% or more of that power and produce better light? What if it was guaranteed to go maintenance free for 7 years? What if it used American raw materials, created American manufacturing jobs, and could have custom designs for your facility? I would give that a big, patriotic, and green “WOW”! Investment anyone?
Here’s a peak at a possible custom design:
Like the racket design? Me too! More peaks in Part 2.
In Part I, we outlined some of the downsides to current Metal Halide (MH) lighting, but don’t get me wrong. MH has served us well for a VERY long time. Now its time for the details, why we need a change, and what the next technology has to offer. Let’s start with the hard costs of MH.
MH Maintenance Costs
What does MH cost per court and what can be saved? Well, we have to make some assumptions, but this analysis will give you an “apples to apples” point of comparison between an MH court and its most likely successor, LED technology. A typical tennis court has 8 MH fixtures (called “Cans”) of 1,000 Watt bulbs or 8000 Watts total. Assumptions: a busy outdoor facility might run them an average of 4 hours a night (an indoor club obviously MUCH more) and 180 nights a year (some climates more, some less). In my city an hour of electricity (a Kilowatt Hour or KWH) costs about 15 cents, times 8 fixtures or $1.20 per hour to light one court. Multiply by 4 hours and you get $4.80 for the night, times 180 nights a year is $864 in electricity costs to light one court. For 7 years, electricity costs $6048. I’ll tell you why we need to use 7 years of power costs below.
My local lighting maintenance vendor charges $105 for the trip, and $95 per lamp or $865 for an 8 lamp court, not including needed transformers, capacitors, and tax, so lets round up to
$900 per court. Individual bulbs may burn out sooner, but this is a reasonable average vendor cost for a budget to maintain appropriate light levels described in Part 1. On an 8-fixture court, over a 7-year period (tell you why “7 years” soon!), you should replace all 8 bulbs twice near the beginning and end of this period, or $1,800. So we have $1,800 in maintenance plus $6048 of electricity over 7 years gives a total operating cost of $7,848.
What Can We Expect Next? Instead of a bulb that loses enormous amounts of energy to heat and sends light in all directions, the likely successor to MH is based on a Light-emitting Diode or LED. You know them from the electronic screens in your TV, phone, and computer. So, why hasn’t LED technology jumped into sports as quickly?
First, even the major lighting companies like Phillips and Sylvania have struggled trying to push enough electricity into the light emitter for sports. But unlike the heat in your computer, the heat for a sports light must be dissipated passively without a fan. Right? It’s been a tricky problem but there are also obvious and HUGE incentives to get it right. Direct light is much more efficient because over 50% of MH light is reflected and tends to spill where it is not wanted. LED light can be easily directed to where it’s needed most on the playing field. In these new sports lamps, the light emitter is encased in 3 inches of shatterproof, solid glass without an air gap. The manufacturer calls it “Explosion Proof” and it might be bullet proof too. Since there is no air at the LED, there is no air pollution, dust, or condensation to block its light over time like MH.
In the pictures below, you can see the clear glass lens and the spokes that passively draw heat away. The core design you see here is EXTREMELY sturdy.
Clearly, and thankfully, the days of the old square “Can” can now be history. LED technology lends itself to an open architecture of customized mounting design choices (see a couple in Part 1). Here are a few more:
This customization also favors native, medium sized companies that are able to quickly adapt to end user needs. These companies would use American raw materials, American employees, and new American factories serving a very large new market. That’s why we say, “Investments anyone?”
Unlike an MH “can”, an LED lamp stays room temperature saving on air-conditioning for indoor use. It won’t break or explode, won’t attract dust or condensation, is instant on/off, does not degrade in performance, can be placed on a motion sensor or a dimmer for mood lighting a party, and can even be remotely controlled from a smart phone. That deserve a high tech “Wow”!
Despite these creative designs, the best innovation is the savings. LED technology is an impressive, environmental alternative to MH power consumption because there is very little wasted electricity. We will know soon if the electricity/maintenance costs will be merely enormous, or spectacular. As of now, it is not known if one or two LED fixtures will be equivalent to one MH 1000 Watt fixture. One complication is that the two light sources cannot be compared with a standard light meter. Yikes!
To give you MORE than 1000 Watts of equivalent light with better distribution, you would need to change each can and pole arm to a fixture for your court that holds one OR two LED fixtures. Let’s assume two for now. Two of the LED fixtures pictured above use ONLY 300 Watts! Even if two are needed, 16 LED’s per court (2,400 Watts vs 8,000 Watts) is an enormous 70% savings or $5494 in JUST electricity over 7 years. That deserves a high tech, very green, WOW! Plus, there’s more.
The service costs are also impressive. Because the LED emitter is encased in shatter proof solid glass, mounted to a heavy gauge aluminum base, the parts/bulbs are unconditionally, 100% guaranteed for 5 years but the expected life is 10 years for the LED chip and the housing is guaranteed for 20 years. ===> That’s why the manufacturer advises a conservative, budgeting choice of 7 years maintenance free. They will very likely go longer.
So, we have another $1,800 saved in maintenance, plus $5494 in electricity, for a total of $7,294 over 7 years. Pretty impressive for one court huh? Again, unlike an MH bulb, this lamp stays room temperature so it doesn’t push air conditioning, does not attract dust or condensation, is instant on/off, does not degrade in performance YEARLY over time like MH, can be placed on a motion sensor, and can even be remotely controlled from a smart phone. That deserves another WOW!
These LED fixtures are designed so that any licensed electrician can do the job. To remove the 8 old arms/cans and install the new LEDs on 8 poles, in parts and labor, is around $15K, so over 7 years about 50% of those costs are returned, at CURRENT electric rates. Most general contractors will agree that‘s pretty impressive for any construction upgrade.
Will electricity costs stay the same? What if just one LED fixture can replace a typical MH lamp? What about LED’s for football, baseball, and basketball? Here’s another option we would like to see get the “green” light:Yes, it’s possible sports lighting of the future might be powered by the sun! The mind truly boggles at the prospects for LED’s in sports and new American workers to get the job done.
One day all elite athletes will have their Dynamic Visual Acuity checked and improved. Until that day, all I can do is present evidence of how important it is and how limited the human eye is in the hyper fast, hyper difficult world of tennis.
Part 1 is an astute investigation of the science and practice of professional line calling. An article that helps describe how difficult a task tennis presents for the human eye. Incredibly, this is just for the poor linesmen who are sitting still trying to focus on one bounce of the ball in one spot. Linesman are actually told to NOT watch the ball! Wow!
In stark contrast to this trained professional linesman, most line calls in our sport are made by players who are running, out of optimal position, and probably feeling obligated to their doubles partner. No wonder the demands can get out of control and cause friction among friends!
Part 2 is an article to help put the Part 1 description into practical application for your tennis. The pros now have the benefit of Hawk Eye technology, the rest of us do not. Hopefully, these articles will help you find the proper perspective on your next line call.
~Best of luck with your tennis!
THE INS AND OUTS OF BORDERLINE TENNIS CALLS
By Alan Schwarz
Published: June 23, 2009, NewYorkTimes.com
When a line judge at Wimbledon rules on a hair-splittingly close call and says the ball is out, the inevitably disgruntled player should not only consider challenging the call for review by digital replay system. He should consult a recent issue of Current Biology.
A vast majority of near-the-line shots called incorrectly by Wimbledon line judges have come on balls ruled out that were actually in, according to a study published in October by researchers at the University of California-Davis. To the vision scientist, the finding added to the growing knowledge of how the human eye and brain misperceive high-speed objects. To the tennis player, it strongly suggests which calls are worth challenging and which are best left alone.
The researchers identified 83 missed calls during the 2007 Wimbledon tournament. (Some were challenged by players and overruled, and others were later identified as unquestionably wrong through frame-by-frame video.) Seventy of those 83 calls, or 84 percent, were on balls ruled out — essentially, shots that line judges believed had traveled farther than they actually did.
Called perceptual mislocalization by vision scientists, this subconscious bias is known less formally to Wimbledon fans as “You cannot be serious!” — John McEnroe’s infamous dissent when, yes, a 1981 shot was ruled out. Now that players can resort to a more evolved appeal procedure, the researchers’ discovery suggests that players should generally use their limited number of challenges on questionable out calls rather those that are called in, because such out calls have a far better chance of being discovered as mistaken on review, then overturned.
“What we’re really interested in is how visual information is processed, and how it can be used to a player’s advantage,” said David Whitney, an associate professor at U.C.-Davis’s Center for Mind and Brain and the paper’s lead author. “There is a delay of roughly 80 to 150 milliseconds from the first moment of perception to our processing it, and that’s a long time. That’s one reason why it’s so hard to catch a fly — the fly’s ability to dance around is faster than our ability to determine where it is.”
This is the third Wimbledon in which players can challenge questionable calls for review by the Hawk-Eye system, which uses high-speed video cameras to record balls’ flight. (About 25 percent of all challenges result in overturned calls.) There is no cost to the player when a call is proved correct, but after three such episodes in a set a player may not challenge again. Whether through strategy or residual tennis etiquette, most players leave many challenges unused.
Theoretically, line judges should be equally prone to call an out ball in as they are an in ball out. But when objects travel faster than humans’ eyes and brains can precisely track them — for example, Andy Roddick’s 150-mile-per-hour serves — they are left having to fill in the gaps in their perception. In doing so they tend to overshoot the object’s actual location and think it traveled slightly farther than it truly did.
Both successful challenge calls as well as the overlooked mistakes that the researchers later identified were several times more likely to come on “long” calls than “in” calls. (The same pattern existed at Wimbledon last year, Whitney said, although the paper did not present that data.) So players are better off using as many challenges as possible on balls called out, because those are the calls most likely to be wrong; if a player thinks an “in” call was wrong, chances are his own eyes were as fooled as line judges’ sometimes are.
Without knowing it, tennis officials are already told to try to compensate for this mislocalization effect. Published instructions for United States Tennis Association line judges tell them to “focus your eyes on the portion of the line where the ball will land,” rather than attempt to track the ball in flight. “Get to the spot well before the ball arrives,” they are advised.
Rich Kaufman, the association’s director of officials and a linesman and chair umpire from 1976 to 1997, said that of all things “one of the hardest things to teach new linesmen is to take their eye off the ball.”
“I once asked an eye doctor, then what am I seeing on a bounce?” Kaufman said. “The doctor said that’s your brain working — you think you see the initial point of impact but it’s the blur of the entry and exit of the ball.”
A player using his knowledge of this effect in challenging calls could see a benefit of about one or two overturned points per match, Whitney said, plus any psychological boost from feeling vindicated rather than robbed. But Whitney added that understanding how the brain misperceives visual stimuli can help in more real-life matters, like the design and placement of high-speed safety equipment, automobile brake lights and warning signs of all types.
As for Wimbledon, it appears as if the new information can only help players, not the judges who vex them. Kaufman said: “You have to call what you see. Or what you think you see.”
HANDLING LINE CALLS FOR RECREATIONAL PLAYERS
by Jonathan Bailin, Ph.D.
Over the years, I have addressed this issue verbally with recreational players from time to time. It is
so important to them however, that it should be placed here for future reference….
Strong, successful personalities often treat recreational tennis as just another litmus test of
their personal success. That their competitive nature in business should be reflected in all arenas
of their lives. Why not tennis?
Because by definition, it is “recreation”. An important word to keep in mind on court.
I hope you have had a chance to look at the above article on eye skills and line
calling I reproduced from the NY Times. VERY RARELY are bad line
calls on purpose in amateur tournament tennis, and practically never in social tennis.
That said, they are an ever present artifact of imperfect eye sight for all players and officials.
It’s clear that some players become hypersensitive to line calls in general, but a more “recreational”
and relaxed approach to this situation is in order. Here is an adult, big picture approach:
No one wants our favorite sport to have any adverse effect on our friendships. Recreational
players are important cogs in each others social wheel. Your goal should be to have many years
of amicable social and competitive tennis ahead, with all players available, at your skill level.
====> To that end, I propose you use a new line call policy on court– If an opponent even looks at you
funny after you make a call, give the point away! <======
This can be confusing and difficult at first, but it is an important response for all tennis players.
First, admit to yourself that if you are not making a living on tour, no matter what “competition”
you are engaged in, you are playing “social tennis”. That is you are in a very small, tightly knit
community which communicates frequently about ALL aspects tennis. More important than any
trophy or team success, your reputation as a mature person, who others enjoy playing with, is at stake.
Social tennis should test skills, not reputations, because tennis should not be at that
level of importance in our lives. Your business, your family, your contributions to the people
around you, the planet, and your health are that important. Not tennis!
In my professional opinion, suggesting to “Replay the point” is not a strong enough gesture of capitulation to
an opponent who has just taken a risk by questioning a call verbally or by body language. Keep
in mind that they already feel awkward. Your choice is to help them relax by showing an expert
understanding of the situation or heighten their fears that they will face ridicule or rejection.
ALL PLAYERS SHOULD RESPOND TO THAT SITUATION BY– asking for their help in making the call “if you saw it more clearly than I did” and graciously, with genuine intent, offer them the point. Let THEM offer to play the point over and do not offer that option yourself. If you are going to capitulate graciously, go the whole way!
This does several things. One, it demonstrates that you understand the challenges for the human eye. Two,
you are mature enough to have your priorities straight in terms of life and the future fun to be had with these same friends, in the next point, and in the next match. Three, that the continuity and spirit of the contest is more important
to you than any particular point. Even match point!
The pros know that one point matters as often as…. ummm…. Halley’s Comet! In that case, the line judge’s
job is to take the grief anyway. For recreational players, one point matters even less often.
Relax and enjoy your friends!
Take Home Tennis (THT)
Some mannerisms of the pros you should take home, others NOT! Which mannerisms are right for me? How do they apply to my game? What does a leading Ph.D. in tennis biomechanics think?
Eastern and western medicine now agree that the body can effect the mind and the mind can effect the body. For tennis players, learning to focus the mind to help prepare the body for the type of intense physical demands
of a competitive point require practice, off the court, and even between points!
Click on the YouTube link below to watch the following sequence which portrays the rituals used by Maria Sharapova before her serve.
Psychologists might call them ritualized behaviors and tennis coaches know that they can make a huge difference in how an athlete responds moments later under competitive stress. Of all the top players, Maria Sharapova’s rituals are probably the most pronounced and predictable.
Each of her ritualized mannerisms can be associated with a useful subtext. Her body “tells” her mind to apply itself to the task and stress of tennis in a sequence of ways. After some repetition, her body and mind learn to respond to these behavioral messages to optimally prepare for a point.
The “Serve and Rituals” video portrays the following messages her body sends to her mind: “Forget about the last point, keep your mind here, get your feet ready to react, secure your hair, get in tempo for the serve”. She set the standard. Look for them in many other players and find the parts of their rituals that are right for you. You can take these home!
“Take Home Tennis” and “THT” are copyrighted expressions of Jonathan (c) Bailin, Ph.D. 2007 and may not be used without his expressed written consent.
Did you know that there is only one human activity which taxes dynamic vision skills more than tennis?
The answer will amaze you and should play a role in your choice of eye protection/sunglass products for tennis. Understandably, few sunglass manufacturers produce product which has the necessary visual accuracy that tennis demands. The task of watching a small ball go from optical infinity to reading distance on such a continuous basis is enormously difficult for the visual/motor system. Pictured below is the miraculously complex visual system with only a couple of its nearby muscles. Don’t forget the brain needs training to interpret what this system sends it, then a call to action is initiated, then the muscles in the rest of the body try to comply!
As background, “static vision skills” are those tested by a typical Optometrist. They are used to read efficiently or see objects clearly at a variety of distances. For example, though this page does not move, your eyes have still learned to recognize the letters, comprehend their meaning, and move smoothly from line to line. A set of skills that can be improved if desired. The movement in these “static” movement skills are related to those required for tennis.
Amazingly, even the most skilled athletes can improve their visual skills with highly specialized and supervised computer exercises. Dr. Polan even guarantees improvement in batting percentage for baseball players! For more information on his incredible work, go to: http://www.DrGaryPolan.com
The key to understanding this new science is that: ALL VISUAL SKILLS ARE LEARNED, NOT INHERITED!
Q. So, what is the most challenging human activity to the “Dynamic Visual Acuity” skills for the eyes? Even more than tennis? A. Jet Fighter Pilot!
Visual Skills of the Human Eye
by Jonathan Bailin, Ph.D. & Dr. Gary Polan, O.D.
Sports Medicine & Ergonomics Associates
Submitted in 1997
The author has collaborated with his associate, Dr. Gary Polan, O.D. many times. Dr. Polan is a pioneer in the field of Sports Vision Training (SVT) and/or Vision Training (VT) since 1984 (*). In 1996, his work received corroboration by the staff at the Jules Stein Eye Institute at the UCLA Medical School (**). Here, we will outline all the individual skills required by the visual system to perform at its peak that now form the science of VT and SVT.
Dr. Polan’s experience in training and improvement of visual skills has resulted in “surprising” advances in most learning disabled cases. Improvements in intellectual activity which are generally unexpected, but very welcomed by parents, have not been well documented by rigorous research designs to date. Still, we are confident that a product like Sportwall will play a significant role in improving reading skills, Attention Deficit Disorder (ADD), and Dyslexia.
Few realize that reading is a motor activity like sports! Just one of the many common reading flaws is transposing letters like “ea” to “ae”. When the number or severity of flaws effects performance or comprehension, VT or SVT is warranted.
So, before any improvement in reading or athletic performance can take place the visual system must be engaged. What are the exact skills that the eyes posses that can influence performance?
Introduction to Visual Skills
First, readers of this proposal should realize that ALL visual skills are learned. From infancy, the vision skills that we take for granted have been built gradually over time. Contrary to folklore, the are not precisely genetically predetermined and can be improved.
Fact: visual skills, no matter how polished by a our activities or sports, can be improved in a clinical or private practice setting. Sports careers, worth millions of dollars, can be improved and lengthened past their usual expirations. One of Dr. Polan’s more famous patients Carl Lewis, says that more of his records would still be standing today had he experienced SVT during his competitive career.
Visual skills can be divided into 3 sub areas: Visual Acuity, Visual Efficacy, and Visual Processing. Visual Acuity is measured by standard optometric tests commonly used for eye prescriptions including standard eye chart examinations.
Visual Efficacy can be measured by testing among the 24 areas listed below which include focusing, convergence, divergence, etc. Visual Processing can be evaluated by tests which measure the extent of learning disabilities such as Reading Disorders, Attention Deficit Disorder (ADD), and Dyslexia as found in items 2, 7, I5, 16, 18, 20, 21, 22, and 24. Most ADD and Dyslexia is responsive to treatments for visual/perceptual deficiencies in these areas of training thus often diminished or alleviated completely.
Visual Efficacy Skills
All movement mechanics during sports are enhanced by eye skills and eye health. In turn, improvements in several areas of eye skills will enhance eye performance during motor activity. For example, reaction time is first dependent on the visual accuracy and recognition skills listed. To acquaint the reader with the proposed research, a brief review of each eye skill which can positively effect motor performance must be considered. Please note that Visual Efficacy Skills are a subset of all the visual skills listed below.
1) Visual Acuity-your ability to achieve a sharp resolution of an image can be divided into static acuity (stationary images) and dynamic acuity (resolution of images in motion).
Static Visual Acuity–Corrected or not, your eyes should have 20/15 vision for high speed activities. “20/15” vision means that is you see at 20 feet what the average person only sees accurately at IS feet away.
Dynamic Visual Acuity–the ability to see sharply while the player, opponent, and ball are all in motion. This ability is made up of many other skills such as Convergence, Focusing, Tracking, and Interpretation, etc. Following the action with the eyes rather than the head or body is more efficient and puts less stress on the balance and muscular-nervous system.
2) Visualization—is the ability to plan, imagine, and prepare for upcoming motor skills and movements. Some sports scientists believe visualization of needed skills is more efficient than coaching “pep talks”.
3) Peripheral Vision–is critical to awareness of other important things while watching the ball such as your teammates, boundaries, or opponents.
4) Depth Perception—is the ability to quickly and accurately judge the distance between yourself and your opponent, teammates, targets, and boundary lines while judging the speed, rotation, and flight path of the ball. Billy J King rates this above court speed and eye-hand coordination for junior tennis players. Quickly diminished by those who stare during the day-students, programmers, and executives may play poorer tennis during the week than week end for this reason.
5) Visual Pursuit—is the ability to use the eyes to follow a moving object smoothly and accurately. This critical skill is based on good eye teaming and eye muscle balance but it cannot track a ball smoothly at high speeds where Saccadic Movement takes over.
6) Saccadic Movement-is the ability of the eyes to “jump” from one point to another when speeds exceed those of visual pursuit. This skill is used in reading to jump from one word to the next. If this skill is poor, reading ability is affected! Quick, accurate saccades are used to survey rapidly with as little head movement as necessary. Head movement is a less efficient method of eye tracking and can confuse balance. Unnecessary head movements, and eyelid reflexes to flinch, must be overcome with training.
7) Visual Concentration-describes the cooperation between Visual Pursuit, Saccadic Movement, and Visualization in the “minds eye” or imagination. This skill is not scientifically well defined yet, but is exemplified by tennis players who must switch concentration rapidly from target, to ball, to processes of planning and prediction which are critical to performance.
8) Speed Of Focusing-is the ability to shift focus from near, intermediate, and far distance. This eye muscle skill is subject to the same fatigue which affects other muscles over the course of exercise.
9) Glare Recovery Speed-is the ability to see clearly after looking toward intense light. Focusing near sun, and at tennis court lights, causes “dazzle” to the retina.
10) Sight in dim illumination.
11) Eye Muscle Stamina-is the ability to withstand fatigue without decreased performance in a variety of eye tasks.
12) Color Perception—is not critical but may play a role in optic yellow against white lines and line calls.
13) Eye Dominance—is the ability of the sight in one eye to dominate images from the other. Tennis players generally prefer strokes on the same side as the dominant eye which is usually the right, for right handed players, over 80% of the time.
14) Fixation Ability-is the skill of preventing eye fatigue which comes from staring at objects too long. Receivers with poor fixation skills fatigue within a few seconds of staring at the server. Other players do not, but staring should be avoided.
15) Visual Memory—is the accumulation of past experiences such as the number of proper swings logged in a players “motor program file”. This combined with visualization for future swings is probably a major factor in consistency during competition. Visual memory fades with time.
16) Spatial Localization-Knowing your position relative to other objects especially while you, ball, and opponent are moving.
16a) Esophoria—players who see the world CLOSER than reality, tend to hit/throw shorter.
16b) Exophoria–players who see the world FARTHER than reality, tend to hit/throw longer. We believe Shaquille O’Neal was a good example of this.
17a) Speed of Recognition Time-is how fast can you identify images.
17b) Reaction Time–How fast can you react to those images.
18) Eyes to Body Coordination–is the ability to integrate what you see into an appropriate and coordinated response from your body parts (aka: Visual/Motor Integration).
19) Contrast Sensitivity—the ability to pick out an important object against a field of other objects.
20) Visual Attention-is the skill used to prepare the eyes and brain which heightens its readiness for an upcoming task. This is a precursor to Visual/Motor Organization. Of course, the body can influence this system which is one reason why elite tennis players bounce during the opponents contact.
21) Figure/Ground–is the ability to pick out an object in the foreground against a variety of background fields; to discriminate the figure to be attended to and to see the interrelationships to its background information.
22) Visual/Motor Organization–is the ordering and organization of motor skills; to choose from a “catalog” of motor programs for meaningful and productive action.
23) Jump Duction–the ability to move from visual tasks that require convergence to divergence of the eyes and back. Jump Duction deals with vergence; the activity of the extraocular muscles to diverge for distance, and converge for near objects rapidly and efficiently.
24) Auditory/Tachistoscopic Skills— are those which help sound and sight skills complement each other during visual processing. It is the auditory/visual integration ability of an individual which coordinates inputs into a meaningful perception and to shift priority and attention from one to the other when necessary. Years ago, preventing air traffic over the US Open tennis tournament in New York was initiated for this reason. Players had to hear the serve as well as see it.
Auditory specialists can better assess the ability to discern background from foreground sounds similar to the way we will assess background to foreground objects. This is an area worthy of much more study. There is much potential to design audio triggers, cues, and scoring tones here. Consider the bell for a horse race!
The list of “Visual Skills” above items 1-24 is Copyright (c) Jonathan Bailin. Ph.D. 1997. Reproduction by author’s permission only.
* Hoflinan, L., Polan, G., Powell, J. The relationship of contrast sensitivity functions to sports vision” Journal of the American Optometric Association 55:10,747-752, Oct 1984.
** Laby, Rosenbaum, Kirschen, Davidson, Rosenbaum, Strasser, Mellman “the visual Function of professional baseball players” American Journal of Opthalmologv 122:4,476-485. Oct. 1996.
Keywords: sports vision training, SVT, vision training, VT, eye skills, reading skills, sports performance, sports career enhancement, visual acuity, visual efficacy, motor learning, eye performance, eye health
Take Home Tennis (THT)
“Take Home Tennis” and “THT” are copyrighted expressions of Jonathan (c) Bailin, Ph.D. 2007 and may not be used without his expressed written consent.
Some mannerisms of the pros you should take home, others NOT! Which mannerisms are right for me?
How do they apply to my game? What does a leading Ph.D. in tennis biomechanics think?
Answer: “THT” can put the “TNT” into your game!
Eastern and western medicine now agree that the body can effect the mind and the mind can effect the body.
For tennis players, learning to focus the mind to help prepare the body for the type of intense physical demands
of a competitive point require practice, off the court, and even between points!
Click on the YouTube link below to watch the following sequence which portrays the rituals used by Maria Sharapova before her serve.
Psychologists might call them ritualized behaviors and tennis coaches know that they can make a huge difference in how an athlete responds moments later under competitive stress. Of all the top players, Maria Sharapova’s rituals are probably the most pronounced and repeated.
Each of her ritualized mannerisms can be associated with a useful subtext. Her body “tells” her mind to apply itself to the task and stress of tennis in a sequence of ways. After repetition, her cody and mind learn to respond to these behavioral messages to optimally prepare for a point.
The “Serve and Rituals” video linked above portrays the following messages her body sends to her mind: “Forget about the last point, keep your mind here, get your feet ready to react, secure your hair, and get in tempo for the serve”. She set the standard that many players on the tour copy. Find the parts of their preparation rituals that are right for you. You can take THESE home!
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