How do you look?

Footbag is a great sport! I think we all agree with that. It’s creative, dynamic, athletic, sweaty communicative, it can trigger a wide range of emotions and feelings and so on and so on. As a student of sport science I had to think about a topic for my thesis 3 years ago and I could have taken all of the aspects mentioned because they are all interesting for sport scientific research. I wanted to have an aspect of footbag in my thesis to make the work less tiring (I know there are some more students of sport science who did the same). The following abstract is from my bachelor thesis with the title: “Influence of visual cues and their meaning for gaze and kinematic behavior while performing complex rotational movements in Footbag”.  It’s acombination of biomechanical aspects and perception.

“The goal of the present work was to investigate the adaptation of gaze and kinematic parameters under different conditions in a footbag specific movement. There is rare knowledge about this topic in recent literature. Only a few studies investigated the correlation between gaze behavior and kinematics under visual occlusion in a sport context (Davlin, Sands & Schultz, 2001; Davlin, Sands & Schultz, 2004; Luis & Tremblay, 2008). In their experiments they analyzed gymnasts while performing a back tuck somersault under different visual conditions. Without using an eye tracking system they found evidence for a visual adaptation based upon changes in the kinematics, e.g. the angular velocity of the head. This study follows their research and tries to underline their findings by using additional eye tracking data in a footbag specific context.

Six experienced footbag athletes (annotation: Thanks Berlin Crew!) were asked to perform a movement called Spinning Clipper under three visual conditions (binocular/Bino; monocular with the left eye closed/MonoLG; monocular with the right eye closed/MonoRG). While performing the movement they wore an eye tracking system. Two full HD cameras recorded the athletes. Kinematic parameters were the angular displacements of the hip, shoulder, two head axis, and the spatial displacement of the footbag. Furthermore gaze variables were the number of fixations (per movement phase), the angular displacement of the eye in x- and y- direction, and the number of eye-blinks.

The results indicate that there is clearly an adaptation of gaze under visual occlusion. The adaptation of the eyes plus the variation of certain kinematic parameters show that athletes used other strategies to perform the Spinning Clipper. All kinematic variables show a temporal and spatial shift under MonoLG and MonoRG. In order to compensate the lack of visual information the athletes turned body segments earlier in a wider range. Concerning the eye movements it is shown that there are more fixations through the whole movement.

As already detected for the body segments the eyes also move in a wider range in x- and y-direction under MonoLG and MonoRG in comparison to Bino. All of the gaze and kinematic differences between Bino and the two other monocular conditions provide evidence of the suggestion that athletes have to adapt their visual behavior in order to perform a task successfully. The results can be seen as a support and an expansion of the findings of the studies dealing with this topic.”

spinningclipperThe picture presents some of the findings in a visual way.

One might think that the findings are quite easy:

Closing one eye + Performing a spinning clipper = Looking and moving differently

I have to admit: It’s right! But there are some practical implications and basic aspects for training in general. What can clearly be said is that vision and motion are adaptive phenomena which means that they can be trained. For the aspect of motion I think it’s clear (mostly) but an athlete can also improve its visual skills. Considering the fact that vision is one of the most important sense in Footbag for control and posture it might be interesting to intersperse volitional visual occlusion into a practice session following the motto: When you see better you play better (One aspect of safety: If you ever tried to play with one eye closed you possibly realized that it is quite hard to estimate the relationship of the footbag to your body so that there is a higher potential for injuries. So don’t try to go for 50 fearless with one eye closed! I would say it’s safer to focus on one particular technique). By the way: No matter if you analyze gaze behavior during a back tuck somersault with two and a half twists or a Spinning Clipper, the pattern of your eye movements are quite unique. That means that you can’t imitate them deliberately. It’s more like a tiny choreography your eyes perform to keep the body under control.

But as the findings prove even the kinematic behavior while performing a certain movement under changing conditions is different. Concerning the principles of “differential motor learning” technical training is more progressive when a certain technique is practiced under consistently changing circumstances. This stands in contrast to classical theories of motor learning where a “perfect” or “ideal” technique is the product of tremendous amounts of repetitions where “mistakes” are unwanted and referred to as “wrong”. The theory of differential motor learning is based on the following proposition: ‘There is no such thing as a repetition of a movement. It’s always a different one.’ I don’t want to say the one is right and the other is not (both theories have their empirical fundaments) but I think that a certain amount of variation in technical training is useful to keep it interesting. Even small variations of the circumstances (e.g. occluding one eye) might have a positive effect on your technical level or your game in general. Every stimulus – that is challenging enough – the body is exposed to is positive in the sense of adaptation and improvement of the personal style of an athlete.

So to end with a quote:

May your style be famous!

Written by Andreas Nawrath

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