United States Ski Team Evaluation
Barry L. Seiller, M.D. Director Vision Performance U.S. SKI TEAM
Although the correlation between athletic performance and visual acuity is clear, there remains no clear picture of cause and effect. In other words, it has not been demonstrated that changes in visual performance are reflected in changes in sports performance. However, empirical studies on the effects of vision training on sports performance are limited and their validity has been addressed recently by two authors. The sports vision field is characterized by an abundance of clinicians, mostly private practice optometrists, with few well trained academic research oriented professionals. Adding to this research problem is the lack of funding for such projects and the inherent variables in any type of double-blind sports-related studies.
The apparent lack of correlation between visual skills training and sports performance enhancement has been frustrating. However, when one thinks about the history of medical research, lung cancers have been linked to cigarette smoking for decades, but only recently has the causal relationship been sufficiently supported by medical research. Doctors have long recommended exercises and attention to fitness as a preventive measure for lifestyle related diseases. Yet, only recently has medical research confirmed that persons who are physically fit are less likely to die from cardiovascular disease.
Therefore, even though an absolute cause and effect relationship has not been defined, it is our premise that visual performance is one of the critical factors in the complex equation that defines sports performance ability. As such, we are convinced that it is essential to assess visual performance and endeavor to correct any observed deficits in visual performance to the highest level possible using the tolls of modern medicine.
Few sports demand better eye-hand-body coordination than skiing. Reflexes must be fast and the skier's eyes accurate. Alpine skiers rely on visual skills to adjust for changes in the terrain, judge their speed and distance, and make split second course corrections while hurdling down hill at greater than 70 mph. Unless the skier can see and shift visual focus rapidly and smoothly from near to far and back again and simultaneously detect changes in the terrain and snow condition, often under adverse weather conditions, he or she will be unable to react in an appropriate time frame. Visual skills affect the skier's reaction time, balance, and eye-hand-body coordination, all of which can make the difference between a mediocre run and a medal winning run.
DESCRIPTION OF THE PROGRAM
The Human Performance Research Laboratory at the University of Utah is responsible for physical performance testing of all U.S. Ski Team members. Concerned about the findings of visual problems in Olympic athletes, the Visual Fitness Institute was asked to develop vision testing and training protocol with the goal of improving their competitive performance levels. The vision testing and training protocol is based on the data gathered from the Olympic Vision Centers established at the Albertville, Barcelona (XVI), and Lillehammer (XVII) Olympic games.
What started as a one time visual evaluation has evolved into a consistently administered long range goal oriented program. The athletes and coaches who were at first skeptical of the program's effectiveness have now come to understand the benefit to performance.
The U.S. Ski Team is composed of Men's and Women's Freestyle (aerial, mogul, ballet), Alpine (downhill and technical), Snowboarding, Cross-Country, Ski Jumping, Nordic Combined, and Disabled Ski Teams. The inherent problem in this program remains the coordination of the availability of the athletes and the support staff in a location conducive to a testing environment. Athletes are constantly on the move. Summer in the U.S. may find the athletes skiing in South America or Australia. Wintertime ski events find them scattered throughout the U.S., Japan, and Europe. There is only a small window of time when the many teams that make up the United States Skiing family are available for testing.
We begin the sports vision evaluations for the U.S. Ski Team with standard vision tests to determine the athletes ability to see stationary objects (static visual acuity), follow moving targets (dynamic or kinetic acuity), contrast sensitivity, depth perception, and muscle balance. This is followed by visual skills testing of eye-hand coordination, eye-body coordination, and central vision eye-hand reaction and response speed. This testing is similar to other investigator's protocol.
Static Visual Acuity
These measurements are taken by the portable Optech 3000 Vision Screener. If the skier's vision is less than 20/20, we may prescribe appropriate corrective lenses. These would include contact lenses, eye glasses (which are usually impractical in this environment), or prescription goggles. Since good dynamic acuity and contrast sensitivity is essential in skiing and is related to good static acuity it is our preference to correct static acuity to optimum levels when feasible.
In the three years that we have performed testing on these athletes, we have found that 39.3% of the athletes of the U.S. Ski Team A, B and C squads of Alpine, Freestyle, and Snowboarding teams (89 subjects) had less than 20/30 vision in at least one eye. While acknowledging the importance of good vision to their performance in survey material, this relatively high incidence of previously unaddressed reduced vision is explained by the nomadic nature of this type of athlete: they are relatively young and often lack any previous structured team vision program.
This "casual" approach to vision by athletes has been verified by the findings in the last three Olympic game Vision Centers that 50% of world athletes never had an eye examination. While startling to the uninformed observer, most U.S. athletic federations do not require vision testing as part of any routine physical examination. The only eye examination facility present in the three U.S. Olympic Training Centers exists as a small one-room office in Colorado Springs, which is staffed by a part time optometrist. Many federation athletes who are candidates for the Olympic team never travel to the Colorado Springs facility.
Since the U.S. Ski Team visual assessment program was initiated, team members have been exposed to consistent visual monitoring and the latest in contact lens technology including Toric astigmatism contact lenses, new soft lens materials such as disposable contact lenses, and their compatible contact lens solutions. This is particularly important since 30.3% of ski team athletes either previously wore or have received contact lenses through the program. This is a significantly larger number of contact lens wearers than the Olympic Vision Center numbers of 15.7%. However, the Olympic surveys included many countries where vision evaluations and correction technology is limited.
The numerical discrepancy between those U.S. Ski Team athletes that had reduced vision (39.3%) and those who were wearing contact lenses (30.3%) is explained by the fact that small refractive errors, particularly those that include astigmatism, make it neither time or cost effective nor convenient for the skier with mildly reduced visual acuity to wear corrective eye wear. For these athletes, it will be necessary to compensate with the appropriate visual clues in order to overcome this visual deficiency.
Dynamic Visual Acuity
Dynamic visual acuity is the ability to maintain sharp clear, sharp, vision of an object in motion, either while the athlete is standing still or in motion. It is relative movement between the target and the observer. Dynamic Visual Acuity equipment tests vision in a horizontal meridian by a rotating disc. It has been maintained that superior athletes have better dynamic acuity. Comparing the ski team results with the large databases described in the literature for the same testing procedures and instrumentation (45.2 RPM) found that ski team members mean scores similar to those published for elite and Olympic athletes. While suggested to be trainable, Dynamic Visual Acuity training is currently impractical because of the lack of qualified training personnel and equipment availability.
Kinetic Visual Acuity
Kinetic acuity is a variation of dynamic acuity. Kinetic Visual Acuity is measured by the KOWA AS-4C Kinetic Vision Tester in which targets are measured as they approach the athlete. This testing equipment, while new to the U.S., has been used for years in Japan for testing driving ability. Kinetic acuity has also correlated positively with improved athletic performance. We will continue to collect kinetic acuity data for future use.
Contrast sensitivity is measured using the OPTECH 3000 Tester. Contrast sensitivity is the ability to visually discriminate shades of gray and black from white and the ability to see variable lighting conditions. While some athletes may have excellent visual acuity, they may exhibit poor ability to see under changing lighting conditions such as from daylight to dusk, twilight to night, and bright sun to shadows. Studies have documented that athletes have higher contrast sensitivity levels than non-athletes and elite athletes possess higher levels than the control subjects. Our testing confirmed that reduced contrast sensitivity correlates with reduced static and dynamic visual acuity. Retesting of the athlete's visual acuity after the appropriate contact lenses have been prescribed results in significant improvement in both their contrast scores and their visual abilities, which they subjectively feel correlates to improved performance. For those athletes whose contrast is reduced and where it is impractical to improve reduced vision, the appropriate tinted goggles to enhance contrast are reasonable alternatives.
This ability to judge distances quickly and accurately is measured by the Writ 4-Dot Test. Identifying 9 of 9 targets is considered to represent excellent depth perception. All skiers tested with static visual acuity of better than 20/30 were able to identify all 9 of the targets. However, those athletes with static visual acuity of 20/30 or below were only able to identify 6 to 8 of the 9 targets. Retesting revealed that all of those athletes whose vision was improved to better than 20/30 with the appropriate contact lenses were subsequently able to identify 9 of 9 targets.
Eye-Hand Coordination is an essential characteristic of the elite skier. Testing for eye-hand coordination has never been standardized; however, large data-based "norms" are available. We tested team members on two devices. The Wayne Saccadic Electronic Board is based on a precise, visually guided motor response in which the subject uses the fingers to press lighted target buttons. The test is conducted in both a subject paced, proactive mode, and in an instrument paced, reactive mode. The score is determined by counting the number of correct buttons pressed during a 30 second test.
The demands of competitive skiing frequently involve shifts in the center of balance of the body to changing visual stimuli. This requires finesse and precision coordinated movement of the lower portion of the body. Gender differences are taken into account. The Wayne Electronic Balance Board attached to the Saccadic Fixator provides a means to assess the athlete's speed in accomplishing shifts of center of balance in four different directions. While testing is not standardized and norms are not well developed, this test gives us an indication of the skier's ability to make a lower body motor response to visual stimuli.
Since the disastrous winter Olympics of 1988 in which U.S. Ski Team athletes failed to score a single medal, the U.S. Ski Teams have enjoyed unprecedented successes, winning numerous medals in Olympic and World Championship competition, and also World Cup events. This new found success can be attributed to a number of factors including a fierce commitment of the athletes, coaches, and support staff.
In addition, to dedicated athletes and staff, the U.S. Ski Team has made a substantial commitment to the application of science and technology to the athlete preparation and competition processes. The result has been many new and innovative performance and training programs. One of the new programs is a unique visual skills assessment battery developed for the U.S. Ski Team by the staff of the Visual Fitness Institute.
The visual testing program described here was started in 1992 and has become an integral component of the applied sports science effort of the United States Ski Team. The visual assessment and enhancement program is one component of a large performance equation which has many complex and interacting variables. To attempt to isolate the factors and indemnify a primary "factor" is naive at this time. However, to ignore any assessable and modifiable factor that may effect performance is equally naive. The sports science staff of the United States Ski Team is convinced that by correcting deficiencies in the athletes visual abilities, their potential for performance on the slopes can be improved.
Professional and amateur athletes alike spend hours each day training their muscles, practicing complex motor skills, honing their routines, and preparing every part of their body and mind for competition in their own special field. To enter the competitive arena with anything but the "best" mind and body is to invite failure. Therefore, in any sport with identifiable visual components, failure to devote resources to the maximization of visual skills reduces the opportunity if the athlete to realize their full performance potential. Our program gives the U.S. Ski Team members that opportunity.
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