INTRODUCTION: Physiological-behavioral complexity emerges from the confluence of organismic, environmental and task constraints and can be assessed through tools evaluating the shape of neurobiological signals; thus, they provide a window into the organization of motor control1,2. Since a profound description of pattern dynamics in sports, and in biathlon in particular, is missing, the aim of the current study was (1) to analyze the time-varying properties of rifle motion and (2) to evaluate whether different settings or techniques would affect underlying coordinative strategies. METHODS: Medio-lateral (GUNx) and up-down (GUNz) rifle fluctuations were captured with a Noptel (Sport II, Oulu, Finland) device at 66 Hz and acquired for 16 Austrian biathletes while prone and standing shooting at rest (3 x 5 shots / position) and during a simulated race on ski rollers (2 x 5 shots / position). Post-processing included the construction of artificial trajectories, reflecting five vertically aligned 80 data point segments of pre-selected aiming intervals for each shooting mode, followed by low-pass filtering (cut-off: 6 Hz) of the resultant time series. Structure-related variability characteristics were calculated using the sample entropy (SEn) algorithm and the obtained indices finally checked by multivariate analyses of variances (MANOVA) - with Alpha fixed at 0.05. RESULTS: MANOVA included both spatial directions and confirmed significant effects for position (F2,15 = 45.5, P < 0.001), condition (F2,15 = 7.2, P < 0.01) and the interaction between position and condition (F2,15 = 4.9, P < 0.05). Subsequent univariate procedures revealed (a) throughout higher SEn indices in the prone than in the stance position (position: all P < 0.001), (b) an increase of SEn for GUNz (condition: P < 0.01) and by tendency also for GUNx (condition: P = 0.12; f = 0.41) when competing, and (c) a stronger influence of preceding physiological load on the structuredness of GUNz sequences in prone compared to standing shooting (interaction: P < 0.01). No such interdependencies were found for SEn values concerning GUNx (interaction: P = 0.71; f = 0.09). DISCUSSION: Findings from the presented experiment have demonstrated a more regular, predictable rifle sway in stance vs. prone shooting, suggesting that subjects intuitively compressed active degrees of freedom into lower-dimensional functional synergies to overcome the greater task demands induced by the former condition. However, the increased SEn outcomes in consequence of fatigue may not echo an optimal performance state - as previously hypothesized in the context of aging and disease1. Instead the noticed less periodic-like rifle tremor, especially in the prone position, shall be regarded as unwanted departures from an otherwise rhythmical intrinsic aiming behaviour, and may therefore be indicative of a loss of flexibility or adaptability in "real" biathlon shooting2. Accordingly, coaches may incorporate specific forms of intrinsic or extrinsic constraints in training and testing for purposefully enriching an athletes' repertoire of movement solutions, which could in case attenuate the impact of (unforeseeable) perturbations. --- The hosting University of Jyväskylä is planning to publish conference proceedings "Science and Nordic Skiing III". In case you are interested in this publication please contact the editors (Anni Hakkarainen anni.s.j.hakkarainen@jyu.fi) to become registered for the book.
© Copyright 2015 3rd International Congress on Science and Nordic Skiing - ICSNS 2015. 5-8 June 2015, Vuokatti, Finland. Veröffentlicht von University of Jyväskylä; University of Salzburg. Alle Rechte vorbehalten. / Übersetzt mit https://www.DeepL.com/Translator