Effects of a Body-Weight Supporting Kite on Sprint Running Kinematics in Well-Trained Sprinters.
Data of elite sprinters indicate that faster athletes realize shorter ground contact times compared with slower individuals. Furthermore, the importance of the so-called "front side mechanics" for elite sprint performance is frequently emphasized by researchers and coaches. Recently, it was demonstrated that using a body-weight supporting kite during full-effort sprints in highly trained sprinters leads to a reduction in ground contact time. The aim of this study was to investigate possible negative effects of this body-weight supporting device on sprint running kinematics, which was not clarified in previous studies. Eleven well-trained Austrian sprinters performed flying 20-m sprints under 2 conditions: (a) free sprint (FS); and (b) body-weight supported sprint (BWS). Sprint cycle characteristics were recorded during the high-speed phase by a 16 camera 3D-system (Vicon), an optical acquisition system (Optojump-next), and a high-speed camera. Paired sample t-tests and Cohen's d effect size were used to determine differences between sprinting conditions. Compared with FS, BWS caused a decrease in ground contact time by 5.6% and an increase in air time by 5.5% (both p < 0.001), whereas stride length and rate remained unchanged. Furthermore, a reduced hip joint extension at and after take-off, an increased maximal hip joint flexion (i.e., high knee position), and a smaller horizontal distance of the touchdown to the center of gravity could be observed (all p < 0.01). These results indicate no negative effects on front side mechanics during BWS and that sprinting with a body-weight supporting kite seems to be a highly specific method to reduce ground contact time in well-trained sprinters.
Christian Doppler Laboratory "Biomechanics in Skiing," Department of Sport Science and Kinesiology, University of Salzburg, Salzburg, Austria.
Sascha
S
Kratky
Michael
M
Buchecker
Jürgen
J
Pfusterschmied
Csaba
C
Szekely
Erich
E
Müller
D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D001835:Body Weight; D005260:Female; D005684:Gait / Q000502:physiology*; D006621:Hip Joint / Q000502:physiology; D006801:Humans; D008297:Male; D064797:Physical Conditioning, Human / Q000009:adverse effects* / Q000295:instrumentation* / Q000379:methods; D012420:Running / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology*; D055815:Young Adult