INTRODUCTION: Biathlon is a complex winter sport combining XC skiing and rifle shooting in 5 shot clips. Race results are determined by skiing time, shooting accuracy and shooting time (Hoffman et al., 1992). Physical exercise is considered to influence shooting performance and accuracy (Hoffmann et al., 1992). It is also reported that fatigue leads to an increase of shooting times (Groslambert et al., 1999) as well as a decline of postural control and rifle stability (Hoffman et al., 1992). Furthermore, physical load was found to negatively impact the constant rifle pressure in the shoulder. Aim of the current study was to identify sub-sets of interrelated factors from a large amount of biomechanical variables and to discover predictors for the shooting performance with and without physical stress.
METHOD: 22 biathletes (8 female, 14 male) from 3 different teams participated in the study: athletes from the World Cup team (WC; n=7), the European Cup squad (EC; n=7) and a youth team (n=8). The subjects had to fire each 3 clips of 5 shots in the prone and standing position in rest, followed by a race simulation on ski rollers over 12.5 km including 2 prone and 2 standing shootings. To quantify fatigue the maximum voluntary isometric contraction (MVC) in the quadriceps, ratings of the perceived exertion (RPE) and the blood lactate concentration were chosen. As biomechanical factors body & rifle sway in (y) and cross (x) shooting line, trigger force and shoulder pressure were measured within 0.5 sec before firing. Shooting scores were counted in rings (1-10). Principal component analyses (PCA) to extract sub-sets of variables and multiple regression analyses were calculated for each condition.
RESULTS: For prone shooting the PCA obtained clear factors (loadings > 0.7): 1) trigger variables, 2) rifle stability and 3) shoulder pressure. In standing shooting 4-5 factors were extracted (loadings > 0.7): Triggering was constant over all conditions while shoulder pressure, body and rifle sway split up differently for each condition. The regression analyses indicated shoulder pressure as a predictor for the score in rest- (p=0.006) and fatigue-shooting 1 (tendency: p=0.10), while in fatigue-shooting 2 no factor could be exhibited. In the standing situation the following predictors for the shooting performance were found: 1) body sway (y-axis) and rifle sway for rest-shooting (p=0.001), 2) rifle sway in x-axis for the first fatigue-shooting (p=0.034) and 3) no prognosticator for fatigue-shooting 2.
DISCUSSION: For prone shooting the shoulder pressure seems to be a predictor for the score, while in the standing condition body and especially rifle sway appear to be relevant. Interestingly, in fatigue-condition 2 no predictors could be found in both, standing and prone shooting. Thus, it can be speculated that biathletes create individual strategies and patterns with increasing fatigue and therefore, no general predictor could be discovered.
CONCLUSION: It seems to be relevant to detect the individual pattern of each athlete in order to find strategies for fatigue-situations like the last shooting in a competition. Interdisciplinary investigations with additional performance determining factors might expose further details in biathlon shooting, particularly under highly fatigued conditions.
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© Copyright 2015 3rd International Congress on Science and Nordic Skiing - ICSNS 2015. 5-8 June 2015, Vuokatti, Finland. Published by University of Jyväskylä; University of Salzburg. All rights reserved.
|Subjects:||biathlon technique shooting fatigue performance|
|Notations:||endurance sports technical sports training science|
|Published in:||3rd International Congress on Science and Nordic Skiing - ICSNS 2015. 5-8 June 2015, Vuokatti, Finland|
|Editors:||A. Hakkarainen, V. Linnamo, S. Lindinger|
University of Jyväskylä; University of Salzburg