Three Dimensional Kinematic Analysis Of Disabled Discus Throwing

Introduction
A goal of the Paralympics games is to provide elite competition to athletes with functional disabilities that prevent their
involvement in the Olympics [1]. Throwing techniques are mainly used to reach maximal object or body segment
velocity at release time [4]. The release speed of a discus throwing will determine the distance of a discus when the
release angle and height are held constant [6]. The aim of this study was to determine if the release velocity of discus
would be determinant to final distance of discus in two different classes of disabled throwers

Methods
Was cinemetry method utilized and recorded by videotape with 2 high-speed (120Hz) cameras (n=7) Brazilian throwers
four F-44 athletes class with disease in low extremity (Poliomielite 3) or (amputation 1) below the knee. Three F-46
class with the same disease (amputation in one arm) on official competition (Figure 1 and 2). 3D space calibration with
17 references points using DLT (Direct Linear Transformation), were X was the throwing direction, Y Vertical
component and Z was the medio frontal. Mean square error was: 0,006 to X, 0,005 to Y e 0,01 to Z; we obtained from
the two-dimensional sequences the throwing sequences in three dimensions. The correlation between 3D speed of
discus release and final distance was calculated.

Discussion / Conclusions
Two athletes had only two valid throws; one to each class, this made correlation inviable. The athletes of F-44 and F-
46 classes presented throwing techniques very similar with no turn; they throwed after horizontal trunk torsion against
the throw movement [3], with booth feet on the ground; the applied technique, decrease the throw velocity because
have no enough accelerative phase. No significant correlation between 3D projection velocity and final discus distance
in the F-44 class. The disease in inferior members there is a limitation factor for throwing (Bartlett, 1991). Maybe the
lower extremity disease difficult the trunk stability in the instant of discus release. Others kinematics components (angle
and height) had more variations than release velocity. Only in the "A" athlete had correlation, but he had two valid
throwing and he had the less mark. Like finding in other studies the release velocity was the more important value to
determine discus distance [6] there was significant correlation between 3D release velocity and discus distance in the F-
46 class. There must be a good stable of trunk during discus release when have no disease on lower extremity provide a
minimal variability of angle and height of release. This stability may decrease others kinematics influence factors to
determine the discus distance. The choose on separed axes os velocity can be justify to obsevate what the component
icrease the resultant component value On F-46 class, top 3D velocity values were obted on axes X, Y, Z and R resulted
on major discus distance. Seems who the variations of angle of release kinematics parameters need to be mensured on
athletes who have disease on lower extremity for more complete avaliations. All results was too low compared with
world record in F-44 (WR) 33,04 and F-46 (WR) 39,95 m. The research demonstrates who data acquisitions during
competition can be made successfully and new researches in cinemetry on paralympics competition can be made to
found more significant results.

References
[1]. ALENCAR, B. (1996) Paraolimpíada: Brasil no pódio. Rio de Janeiro: 1997
[2]. ATWATER A E (1979) Biomechanical analysis of different pitches delivered from the win up and stretch positions.
[3].BANJA, T. (1999) Velocidade linear e posicionamento articulares no lançamento de disco paraolímpico: Análise
3D em dois diferentes suportes de fixação. 85 unpublished monograph.
[4]. BARTLETT, R (1991) The biomechanics of discus Throw: A review. Journal of sport science vol.10 467-510
[5]. DINU, D; VANDERWALLE, H; TRANCHANT,M (2003). Analise cinematique du lanceur de disque: Etude
preliminare. On-line
[6]. FINCH, A (2003). Kinematic comparison of the best and worst of the top men’s discus performers at the 1996
Atlanta Olympic games. On-line
[7]. World Almanac & Book of Fact(2003)s: Paralympics. On-line

NOTA: O texto com a iconografia está no anexo.

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