|
Optimum Take-Off Angle
in the
Long Jump
Introduction
Optimum Take-Off Angle
Undergraduate Teaching
Introduction
One of the best known 'results' of the science of mechanics is that the
optimum projection angle for achieving maximum horizontal range is
45°. However, it is also well known that actual performers in
projectile-related sports seldom use an angle of 45°. For
example, typical take-off angles of world-class long jumpers are around
21°. Some researchers have noted that in long jumping the
landing is about 50 cm lower than the take-off. Even so, this produces
only a small reduction in the calculated optimum take-off angle (to
about 43°)

The reason for the discrepancy between theory and practice is that the
take-off speed attained by the athlete are not
independent of the take-off angle, as is assumed in the conventional
calculation of the optimum take-off angle. Experiments have shown that
the take-off speed an athlete can generate decreases
with increasing take-off angle, and that this substantially reduces
the optimum take-off angle.
Optimum Take-Off Angle
The
idea that the optimum take-off angle in the long jump is about
43° may be understood by using the well-known formula for the
range of a projectile in free flight.

A
series of distance versus take-off angle curves may be plotted for
selected take-off speeds. These curves suggest that the optimum
take-off angle is just under 45°.

This
set of calculations contain a serious error. The calculations do not
include the fact that an athlete cannot jump with
the same speed at all take-off angles. The take-off speed an athlete
can generate steadily decreases as the athlete
tries to jump with a higher and higher take-off angle.

The
optimum take-off angle for the athlete is obtained by combining the
speed-angle relation for the athlete with the equation for the range of
a projectile in free flight. The optimum take-off angle for the athlete
is not just under 45°, but about 22°.

The
optimum take-off angle calculated above applies only to the athlete in
question.
Each athlete has a unique speed-angle relation that depends on their
size, strength, and jumping technique.
This means that each athlete has their own specific optimum take-off
angle.
The optimum take-off angle for a world-class long jumper may be
anywhere from 15° to 27°.
To
find out more about the long jump take-off angle study, see:
Linthorne,
N.P., Guzman, M.S., and Bridgett, L.A. (2005).
Optimum take-off angle in the long jump.
Journal of Sports Sciences,
23 (7), 703-712. (Publisher)
Linthorne,
N.P. Optimum angles of projection in the throws and jumps.
SweatPit.com.
Optimum Projection Angles in
Undergraduate Teaching
My
work on optimum projection angles has been incorporated into my
biomechanics classes. I have produced a Microsoft Excel spreadsheet and
graphing tutorial to examine the optimum projection angle in
shot-putting.
This tutorial highlights to the student the fact that the optimum
projection angle in sports is not 45°.
|