From Adidas MiCoach to Nike+, currently there are a handful of personal training systems developed for runners and cyclists. Outside of these two fields, very few wearable technology systems have been designed for other sports.
Motivated to expand the research of wearable technology products for athletes, Sebastiaan Pijnappel, an interactive product designer, developed an experiential wearable prototype for pitchers that not only measures pitching rhythm, but also provides aural feedback.
How It Works
The wearable system measures timing of "key phases of pitching movements" and directly translates movement to an auditory feedback. The goal was determine whether sounds associated with movement would improve a pitcher's consistency.
Although the study sample was small, three out of the four test subjects showed improvement as a result of the auditory feedback.
More research is certainly needed, but can't you just see incorporated with the WII fit?