Thursday, May 1, 2014

The Eyes Have It...

As coaches, maybe the first thing we notice about an athlete is their height in relation to their age. We might notice that bang from a fluid canon of an arm sending some poor Molten Pro Touch to its wooden grave. We might even go one step beyond and look at the length of a player’s arms, the size of their hands or the length of their calves which may have direct correlation on their subsequent performance.

Maybe what we should be looking at is their eyes!

Athletic performance and eye sight go hand in hand with sports that require quick movements and reaction time. Between 1993 and 1995, a group of ophthalmologists tested the vision of 387 players in the Los Angeles Dodgers organization. A normal human’s eyesight is considered perfect when it’s 20/20 but the Dodger’s players AVERAGED 20/13 and only a small number of players, usually pitchers, were worse than 20/20. In fact, 2% of those tested leaned against the theoretical threshold for the human eye, (thought to be 20/8 vision) testing in at 20/9! A similar study of U.S. Olympic athletes found elite softball players to average a visual acuity of 20/11!

Darlene Kluka is a preeminent expert of visual acuity in sports at the Barry University School of Human Performance and Leisure Sciences in Miami Shores, Florida. “Vision just may be the most variable and selective of all the senses.” She says. “Attempting to observe fast movements that occur in sport places great demands on human vision.”

She helps break down the process we all take for granted. “The eyes send information to the brain, where it is integrated and interpreted as a three dimensional (3D) phenomenon. The information from both eyes into a 3D image is called fusion. Fusion is needed to accurately locate the ball when it moves in time and space.”

Kluka points out that without a conscious effort to attend to something, the eyes will continuously move throughout the field of vision. “When something gets our visual attention, we may focus both eyes on the object. This pause is called a fixation.” She says.

Now why is it important that we know about fixations you might ask? “Fixations are important because focusing ability is limited to only 3 degrees of visual angle.” Kluka comments. She points out if you hold your thumb straight out in front of you and look at your thumb nail—that is approximately 3 degrees of visual angle! Kluka adds, “It is assumed that when your eyes fixate on something, information is being recorded by your brain to assist in visual perception or the decision making prior to motor program initiation. The rest of what you see is peripheral.”

As you read this blog, (all three of you), your eyes must move so that the 3 degrees of visual angle are used to pick up the words while the peripheral vision provides a view that there are additional words to either side of your focus.

Two athletes that have a lot in common are a hockey goalie and a libero. They are subject to super human reflexes and reactions and their play can dictate their team’s success or failure more often than not so it should be asked, what are these athletes fixating on when playing?

Researchers at the University of Calgary's Faculty of Kinesiology have found that the difference between elite goaltenders is what their fixation is on before they make a save;  the puck. The best goaltenders rest their gaze directly on the puck and the shooter’s stick almost a full second before the shot is released making the save 75% of the time. Graduate student Derek Panchuk says, “Looking at the puck seems fairly obvious until you look at the eye movements of novice goaltenders, who scatter their gaze all over the place and have a much lower save percentage than the elite goalies.” The study also showed the distance of the shot doesn't seem to matter, as long as the goalie concentrated their gaze on the puck and stick in the critical second before it's released.

Two-time United States Olympic libero Nicole Davis shares an interest in these studies. The Women’s USA National team coach Karch Kiraly and Davis were working on this in practice just this week. “I have been working on seeing the line of the serve earlier.” Davis says, who has 20/16 vision. They conducted an experiment where Nicole alternated between focusing on the ball for 8 serves, and then focusing on the server's arm for 8 serves, for several rounds each.  

“With pretty conclusive numbers, when my focus is more on the BALL in serve receive, from toss, through the line to contact, my results were much more consistent in terms of how early I saw the path, how early I got my angle out and also my ability to make last minute adjustments, as well as quality of the pass.” Davis says.  “Obviously, or maybe not, it's a little counter-intuitive to stare at the ball, because the server is the one acting on the ball and giving you the cues as to where the ball might go.  All of that comes into view, in a wider focus (peripheral), as the server is contacting even though the focus is mainly on getting a good look and following the ball.”

The National team also experimented with eye goggles that had a tracking device on them to see what players were watching while playing defense. (You can see a sample of these on this video with soccer star Renaldo ) “One thing that we noticed in common for those of us getting a good ‘read’ on the situation, is that we get our eyes on the next actor of the ball quite early.” Davis observed, adding conversely from serve receive, “Not a lot of time on defense is spent staring at the ball.”  

Unlike serve receive, the trained eye moves past the fixation point and to what will come next. “Once we see the quality of the pass, before it reaches its peak, the eyes immediately shift to the setter's contact point and relation to her body, so often her shoulders and hands.” Davis points out.  “Once the setter releases the ball, the eyes shift immediately to the hitter, and more specifically the hitter's shoulder and elbow.”  

There are lots of clues that setters and hitters give defenders that tell them where they are setting or hitting, but Nicole says the shoulders often are the easiest tell.  “Hitters tend to have a lot of tension in their torso when they are hitting hard, or will kick up their legs and not pull the elbow back as far when hitting off speed or roll shots.  Setters will take the ball at different points, some will pivot and some will square to the set while others might try to disguise it longer.  There is a lot of information to process on defense in a split second, so the earlier you can get on the actor of the ball and pick up the tells, the earlier read you can make.”  

A different set of visual skills seems necessary for serve receive and defense. “My theory as to why the sequence is a little different for serve receive is that the ball has longer to travel and can often change direction, and it's important to follow it from start to finish.” Davis surmises.  

Kluka agrees with Davis. “Focusing visual attention on important cues while visually searching can lead to good decisions in competition. This has been referred to as effective anticipation.” She adds, “Skilled volleyball athletes may not be aware of the important visual cues they are attending to.”

Kluka sums up the role that Coaches can play in the enhancement of a player’s vision. “As coaches develop and use drills, drill objectives are important. Each drill must have multiple objectives that have measureable outcomes, one of which includes visual perception and decision making. By including this objective to each drill, coaches are more likely to find multiple outcomes that are in a more game-like environment.”






No comments:

Post a Comment

Post a Comment