Povezanost izabranih kinematičkih parametara i duljine skokova na natjecanju u skijaškim letovima

The objective of this study was to analyse selected kinematic parameters (time of flying, in-run velocity, take-off velocity, out-run velocity, height of flying at 17 m, height of flying at 75 m, height of flying at 120 m, aerodynamic index at 17 m, aerodynamic index at 75 m, aerodynamic index at 120 m) of the best world-class ski jumpers participating in the two final individual competitions (Friday and Sunday) of the Ski-Flying World Cup at Planica, Slovenia in 2009 (HS 215 m). All jumps were recorded with three video cameras operating at 50 fps, following the jumpers at the early flight phase (17 m from the take-off edge) and in the middle phase of flying (75 m and 120 m from the take-off edge). The ski jumpers were divided into three statistically significantly differentiated quality groups according to their jump lengths in all three rounds (Fprob.=.01). By means of correlation analysis and single-factor analysis of variance, a smaller number of statistically significant correlations between the defined kinematic variables and the jump length were determined. The differences in the vertical height of flying confirmed a tendency towards positive correlations between this variable and the jump length (rmin=.42, rmax=.79). The group of the best ski jumpers demonstrated a statistically significant higher vertical height of flying curve in all the three competitive rounds at the points of 75 m (Fprob. were between .00 and .08) and 120 m (Fprob.=.01). The best group of ski jumpers had better aerodynamic positions in the flight phase, especially at the point of 75 m (Sunday, the first round, r =-.73; p =.00) and 120 m (Sunday competition in both rounds, Fprob.=.01).Cilj je ovoga istraživanja bio analizirati izabrane kinematičke parametre (vrijeme leta, brzinu na skakaonici, brzinu odraza, brzinu leta, visinu leta na 17. metru leta, visinu leta na 75. metru leta, visinu leta na 120. metru leta, aerodinamički indeks na 17. metru leta, aerodinamički indeks na 75. metru leta te aerodinamički indeks na 120. metru leta) najboljih svjetskih skijaša letača koji su sudjelovali na dva finalna natjecanja Svjetskoga kupa u skijaškim letovima (petak i nedjelja) na Planici (visina skakaonice 215 m), Slovenija, 2009. godine. Svi skokovi bilježili su se trima kamerama, 50 slika u sekundi, a letači su bili snimani tijekom početne faze leta (17 metara od odraznoga ruba skakaonice) te u središnjem dijelu skoka (75 metara od odraznoga ruba skakaonice i 120 metara od odraznoga ruba skakaonice). Skijaši su bili podijeljeni u tri statistički značajno različite kvalitetne grupe, određene prema duljinama skokova u sve tri skakačke serije (Fprob.=0,01). Korelacijskom analizom i univarijatnom analizom varijance utvrđena je statistička značajnost manjega broja korelacija među definiranim kinematičkim varijablama i duljine skoka. Razlike u vertikalnoj visini leta potvrdile su tendenciju prema pozitivnim korelacijama između navedene varijable i duljine skoka (rmin=0,42, rmax=0,79). Skupina najboljih skijaša letača postigla je i statistički značajno višu vertikalnu visinu krivulje leta u sve tri serije letova u točki 75 metara od odraznoga ruba skakaonice (Fprob bila je između 0,00 i 0,08) i u točki 120 metra od odraznoga ruba skakaonice (Fprob.=0,01). Najbolja grupa skijaša letača imala je bolju aerodinamičku poziciju tijekom faze leta, osobito u točki 75 metara od odraznoga ruba skakaonice (prva serija u nedjelju, r =-0,73; p =0,00) i u točki od 120 metara od odraznoga ruba skakaonice (obje skakačke serije u nedjelju, Fprob.=0,01)