INFLUENCE OF CALCULATION PARAMETERS ON NONLINEAR DYNAMICS MEASURES

Nonlinear analysis methods based on a dynamical systems approach have become more prevalent in recent biomechanics studies. The aim of this study is to identify the range of time delay and embedding dimension values estimated for gait data, and how sensitive Lyapunov exponent and correlation dimension are to the range of these values. A participant walked at 3 km/h and ran at 9 km/h on a treadmill for 2 minutes. Lyaponuv exponent and correlation dimension were calculated based on a combination of the optimal and mean average time delay (TD) and embedding dimension (ED) for both angle and marker data. In the majority of literature, only one ED and TD is considered for LyE estimation, based on an average across data or values suggested in previous papers. However, the results of our study show that every angle or position, has an optimum ED and TD, and the use of these values affects the nonlinear dynamics values in non-trivial ways

LIMIT CYCLE DYNAMICS ACROSS ELITE MALE ARTISTIC GYMNASTS

Biological systems described by their attractor dynamics provide a method to understand the fundamental characteristics of skilled movement. Here the limit cycle dynamics of the longswing were investigated across tiers of elite men’s gymnasts. Senior, junior and development elite gymnasts (N=21) performed three trials of eight consecutive longswings on high bar. Limit cycle analysis revealed a more symmetrical angular velocity of the centre of mass about the bar trajectory in phase space, higher recurrence, lower correlation dimension and lower variability for senior gymnasts suggesting a more deterministic, efficient and predictive technique. The addition of non-linear dynamics to traditional biomechanics offers complementary theoretical and coaching knowledge to movement coordination, control and skill

DYNAMICS OF A CYCLIC TASK BEFORE AND AFTER A CHANGE IN TASK CONSTRAINT: HORIZONTAL BAR LONGSWING

Returning to a consistent technique after a change in skill allows gymnasts to improve routine fluidity. This study investigates the limit cycle dynamics of the mass centre (CM) after a variation in task constraint during the horizontal bar longswing (LS). Gymnasts (n=12) from 3 different age categories completed 3 x 8 consecutive LS with LS four and five as accelerated LS. Senior gymnasts presented the most consistent limit cycle trajectory and lowest correlation dimension (CD) post- compared to pre- task constraint. Senior gymnasts displayed significantly lower CD post- constraint compared to both junior (p = .016) and development gymnasts (p\u3c .001). The increased proficiency attributed to senior gymnasts appears to increase the stability features of the LS limit cycle of the CM angular velocity after an imposed task constraint which may indicate readiness to progress to more complex horizontal bar skills