Three-dimensional hand movements during the execution of ball juggling: Effect of expertise in street performers

Hemodynamic Response Alteration As a Function of Task Complexity and Expertise—An fNIRS Study in Jugglers

“…The implementation of the described cinematographic approach uses OpenCV (Bradski, 2000 ). After this reconstruction we rated the individual trials with three kinematic parameters (Mapelli et al, 2012 ) to find the level of expertise for each juggler: tosses per second, velocity of the toss, angle of the toss (for left and right hand). For all three parameters, we calculated the average stability, that is, the coefficient of variability independent of the average.…”

Postural Control During Cascade Ball Juggling

“…For instance, Leroy et al (2008) investigated how posture is organized during cascade juggling; their results showed that, although arm patterns and sacrum lateral oscillations were spatially similar between groups, experts' latencies between the maximal flexion/extension of the elbow and the maximal lateral oscillations of the sacrum and their standard deviations were significantly lower as compared to the intermediate group, suggesting that experience modified the posture-juggling coupling. Expert jugglers are able to perform better anticipatory postural adjustments, allowing them to improve stability of arm and body movements aimed to correct ball trajectories (Hashizume & Matsuo, 2004;Huys et al, 2003;Leroy et al, 2008;Mapelli et al, 2012). Increased postural stability due to motor learning or development has been reported in other skills, such as rifle shooting (Era, Konttinen, Mehto, Saarela, & Lyytinen, 1996), gymnastics (Garcia, Barela, Viana, & Barela, 2011;Gautier, Thouvarecq, & Larue, 2008), manual rhythmic movements (Amado, Palmer, Hamill, & van Emmerik, 2016), and circus activities (Sahli et al, 2013).…”

“…The juggler must throw each ball sufficiently high to provide time to deal with the other balls (Haibach, Daniels, & Newell, 2004). Previous studies have mostly analyzed learning and coordination dynamics of arm movements during cascade juggling (e.g., Huys, Daffertshofer, & Beek, 2003, 2004Mapelli et al, 2012). Postural stabilization during juggling is important because it facilitates the juggling activity through balance adjustments made before, during, and after arm movements, which maintain reference values in the face of perturbations arising within the juggler (i.e., hand movements) or from external events (i.e., ball movements) (Leroy, Thouvarecq, & Gautier, 2008).…”

Contribution to hand functional assessment based on its kinematics

“…Although correlation of errors with hand length has been found, resulting errors are acceptable without hand size correction. For the use of the instrumented glove in further experiments for studying ADL, sample rate of 75 Hz is considered as appropriate according to literature, only being required frequencies over 100 Hz for sports purposes (Nowak & Hermsdorfer 2009;Imamura et al 2007;Mapelli et al 2012;Dinu et al 2012). Healthy subjects as well as the pathological ones who participated in the further experiments focused on ADL have been asked about the stiffness of the glove, and have reported good level of comfortability.…”