INTRODUCTION: Double poling (DP) received great attention by researchers in last years, because of its increasing use during classic cross-country skiing races. Often, it is the dominant or exclusive technique used over the entire track. An our recent study monitored the whole body kinematic during DP, demonstrating how COM displacement can affect poling force exertion, cycle timing and energetics of DP. New information are needed about the effects of fatigue on DP biomechanics. The principal aims of the present study were to verify the fatiguing effect of a shortterm, high-intensity DP exercise and to evaluate the biomechanical alterations occurring after fatigue in the DP technique, in high-level cross-country skiers. METHOD: Eight skiers performed a 5-min sub-maximal DP trial (20 km/h and 1° inclination) before (PRE) and after (POST) an incremental DP test to exhaustion, while roller skiing on the treadmill. An integrative analysis of DP was carried out PRE and POST, measuring metabolic parameters, COM vertical displacement, body inclination (Theta), pole and joint kinematics, poling forces and cycle timing. Muscle fatigue was considered in triceps brachii, latissimus dorsi and teres major muscles, by calculating the Dimitrov' fatigue index (FInms5) of specific EMG-signal segments recorded during consecutive poling phases. RESULTS: An increasing trend of FInms5 across consecutive DP cycles in latissimus dorsi and teres major muscles, higher blood lactate concentration (P = 0.001), elevated rate of perceived exertion (P = 0.005), together with a reduction of poling force exertion (P = 0.020) delineated a clear state of fatigue during POST. No statistical differences were found in COM vertical displacement (P = 0.968), body inclination (P = 0.087), joint and pole kinematics (P = 0.415) between PRE and POST. Cycle characteristics were affected by fatigue, with a reduction in recovery phase (P < 0.001) and cycle (P = 0.001) duration. DISCUSSION: The incremental DP test to exhaustion elicited a localized and general state of fatigue in high-level cross-country skiers, reducing poling force exertion capacity but not altering the whole body kinematics. DP cycles became shorter and frequenter after fatigue. CONCLUSION: The whole body biomechanics of DP is not altered by a short-term, high-intensity and fatiguing DP exercise. Cycle duration results shorter after fatigue because of a reduced poling force exertion. Future analyses should asses if other type of short-term, high-intensity or longlasting fatiguing protocols should alter the whole body kinematics of DP in high-level skiers, with further negative consequences on performance. --- 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. Опубликовано по University of Jyväskylä; University of Salzburg. Все права защищены.