Transcript High Jump - Sheffield Hallam University

High Jump
Introduction
The two videos that are being analysed are:
• Stefan Holm (Sweden) jumping at 2.34 meters unsuccessfully.
• Stefan Holm (Sweden) Jumping at 2.34 meters Successful.
The purpose of this presentation is
to analyse two high jump
techniques that could be improved.
The analysis undertaken is from
referenced biomechanical
principles,
Both videos are analysed by
angle of curve at entry and
then correlated to angle at take
off. This gives us an idea of
angular velocity before take off
and whilst in flight phase.
Technical Analysis Approach
• Approach Phase
Tan and Yeadon (2004) Suggest that a tightening curve towards the end of the
approach will lead to an increased inward lean velocity. This is important as the
greater the velocity before takeoff the more chance of success.
Figure 1. " Backward lean angle and inward lean angle are the
angles made with the vertical by projections of the foot – centre of mass line FG on vertical planes
parallel and perpendicular to the horizontal velocity v." (Tan and Yeadon 2004)
Technical analysis Continued
Several coaches
have suggested
that the curved
approach is
useful in
developing this
somersaulting
motion during
the take-off
phase
(Fix, 1981;
Jacoby, 1986;
Paolillo, 1989
cited in Tan and
Yeadon, 2004)
Tan and Yeadon
(2004) suggest that
on approach the
inward lean angle
should be
approximately 300
then decreased to
00 by the final foot
take off. The
tightening of this
approach curve
leads to an inwards
lean
rotational velocity
which helps
develop the
somersaulting
motion.
Approach Phase
Unsuccessful
27.5
Successful
31.8
On approach both attempts shows very little difference in inward lean
angle although the successful jump has a larger lean angle therefore
can create a larger angular velocity which will develop a more efficient
somersault motion. This may be the reason the jump is successful.
Technical Analysis Takeoff
•
Depena (1980) suggested that the main purpose of the inward lean on
approach is so, the performers are positioned leaning away from the bar.
This will create a successful attempt.
•
Tan and Yeadon (2004) recommend that at take off the inward lean angle
should decrease from 300 to 00. This will create a vertical takeoff velocity
and slight anglular velocity to travel up and over the bar.
Technical analysis Continued
• Takeoff
Lees et al (2000) suggest that the arms in the takeoff phase have a greater
influence on performance than the lead leg.
The inside shoulder should not drop in towards the bar and both arms
should be swung upwards with the free leg (Mac 1997).
Grieg and Yeadon (2000) explain from their
research that at leg plant (before take off)
The greater the angle at the knee the
higher the jump height. See Figure 2
Figure 2. Leg plant vs. Jump Height
Takeoff Phase
Unsuccessful
Successful
4.7
4.9
In both attempts at immediate toe off, Stefan Holm converts
his inward lean to a near vertical takeoff. This is supported
by Tan and Yeadon (2004) as a successful takeoff.
Takeoff Phase 2
Unsuccessful
Successful
8.2
2.7
After immediate takeoff in the unsuccessful jump, Stefan Holms
lowers his shoulder therefore his arm bends making his approach
angle to the bar a lot greater. This makes his overall attempt lower
and consequently he hits the bar making it an unsuccessful jump.
The successful jump demonstrates what the literature suggests.
Stefan keeps his vertical angle by not dropping his shoulder and has
a greater angular velocity (see slide 6) which creates height and a
well developed somersault rotation. The arms are one of the most
important aspects and this is the key difference between the two
techniques which allows Stefan to succeed.
References
•
•
•
•
•
Tan, J,C. and Yeadon, M,R. (2004) Why do high jumpers use a curved approach.
Journal of Sports Sciences. 23(8): 775-780.
Lees, A, Rojas, J, Cepero, M, Soto, V, and Gutierrez, M. (2000). How the free limbs
are used by elite high jumpers in generating vertical velocity. Ergonomics. 43(10);
1622-1636.
Depena, J. (1980) Mechanics of rotation in the Fosbury-flop. Medicine Science
Sports and Exercise. 12(1): 45- 53.
Mac, B. (1997). High jump fosbury flop. http://www.brianmac.demon.co.uk/highjump/.
[last revised 15/03/2007].
Greig, M.P., and Yeadon, M.R. (2000). The Influence of Touchdown Parameters on
the Performance of a High Jumper. Journal of Applied Biomechanics.16. 367-378.