What is the physics behind increasing the length of a long jump using
weights. Please see the article referenced below:


Swinging Long Jumpers
By HENRY FOUNTAIN

Athletes who can run and jump fast and far spend a lot of time trying
to go faster and farther. But performance enhancement is not limited
to the modern athlete. In ancient Greece, starting in 708 B.C.,
Olympic pentathletes received some help for the long jump in the form
of halteres, weights of stone or lead that they held in their hands
and swung as they jumped.
Researchers from Manchester Metropolitan University in England have
now determined how much help the halteres provided. By swinging the
weights, with a total mass of 4 to 20 pounds, a standing long jumper
should have been able to add about 7 inches to a 10-foot jump, they
report in the journal Nature.
The researchers used software models of jumpers' using halteres of
various sizes and actual athletes using halterelike weights. They
found that, given the same takeoff speed, swinging the weights forward
during the first part of the jump and backward before the landing
shifted the center of mass of the jumper, lengthening the parabolic
trajectory.
Swinging weights, however, might be expected to reduce the takeoff
speed and thus the length of the jump. The researchers' model found
that to be true, but only when the total weight exceeded about 25
pounds. With halteres weighing about six pounds each, takeoff speed
actually increased 2 percent. The researchers suggest that this is
because muscle power does not increase in a linear way. Greater force
can be achieved at the slower muscle contraction speeds that having to
lift a weight will produce.
In the study, the optimal weight of a pair of halteres closely matched
the weight of specimens that have been found at archaeological sites.

Dear hdubin-ga;

Thank you for allowing me to research your question.

The physics behind the use of “halteres”, as these weights are called,
has been known for centuries, In fact, Aristotle himself wrote about
them and expounded on his theories, which were surprisingly close to
what is actually known by science today.

Alberto Minetti, of the Centre for Research Into Human Movement at
Manchester Metropolitan University, has studied the use of halteres in
depth and has even recreated some the results using ancient methods
and modern day subjects. Minetti determined that the ideal weight for
a pair of halteres is between 5kg and 6kg, very close to the size of
halteres unearthed at various archaeological sites.

The use of halteres was very simple. They were swung back and forth by
a competitor just before takeoff, allowing for the built of momentum.
The competitor would then thrust the halteres directly in front of
himself during the first part of the flight. In mid flight the
halteres would be swept backward toward the rear just before landing.
Minetti’s study suggested that if a loaded body can take off at the
same speed and angle as an unloaded body, the loaded jump should be
longer. The loaded jump is longer than an unloaded jump because the
competitor’s center of mass shifts forwards and higher at takeoff, and
back, away from the feet, on landing. Some ancient images even depict
jumpers throwing, or releasing the halteres prior to landing. In
experiments conducted using this method Minetti noted that as the
halteres fly backwards, the feet of the jumper move an few centimeters
forwards. As the halteres slow dramatically during flight and their
position is shifted from front to rear, the jumper simply pushes away
from them and releases them. The newly unloaded jumper, whose
originally jumped hard enough to propel 5kg to 6 kg more than he
actually weighs, suddenly becomes lighter and his center mass shifts
much father forward. The brief mid-air push in a sling-shot type
fashion from the slowing halteres gives him added forward velocity
resulting in a longer jump.

You may be able to picture this later concept in your mind my imaging
a truck pulling a heavily loaded at 100 mph. If the wagon is suddenly
released from the truck, the forward velocity of the truck is
significantly, though briefly, increased. This brief increase in speed
is all a jumper needs to gain the edge since his flight time is very
limited. The relatively small weight of the halteres and the
relatively slow speed that a human runner can attain at the height of
his speed accounts for the advantage of mere inches rather than
several feet. If a human could run much faster while bearing a heavier
load of halteres, in theory at least, the advantage would be much more
impressive.

I hope you find this information useful. I look forward to working
with you again in the near future.

Best regards;
Tutuzdad-ga


INFORMATION SOURCES


“Guardian Unlimited - How the Greeks jumped to it”
http://education.guardian.co.uk/higher/artsandhumanities/story/0,12241,839679,00.html

“Performance Boosting Goes Back to Ancient Olympics”
http://www.hon.ch/News/HSN/510242.html

“Weights gave Olympian long-jumpers a hand”
http://www.nature.com/nsu/021111/021111-8.html

“National Geographic - Ancient Olympians: Weighted Down to Win”
http://news.nationalgeographic.com/news/2002/11/1114_021114_GreekAthletes.html

“The Pentathlon”
http://www.perseus.tufts.edu/cl135/Students/Kristina_Angus/pent.html

“Long Jump” (photos of ancient images depicting the jumping process)
http://www.hum.utah.edu/~rstewart/jumping.html


SEARCH STRATEGY


ENGINE USED:

Google ://www.google.com


SEARCH TERMS:
ancient weights long jump
physics ancient halteres

Very quick turnaround (less than 12 hours). Answer was appreciared.

To tutuzdad.  (question id. 113933)  You said;
"You may be able to picture this later concept in your mind my (I
assume you meant *by* instead of "my") imaging (imagining?) a truck
pulling a heavily loaded (wagon, I assume) at 100 mph. If the wagon is
suddenly released from the truck, the forward velocity of the truck is
significantly, though briefly, increased."

I have a few questions (and comments).  
   If the wagon is "suddenly released" what accounts for any change in
the velocity of the truck?  I will assume that the road is straight
and level.  Does "significantly" depend on the mass of the wagon? 
It's rolling friction?  The mass of the truck?  The VELOCITY of the
truck?  Could it not be GRADUALLY released?  What does briefly mean in
this case?  What is responsible for the cessation of the effect, the
possible use of cruise control?  (include a digression on inertia
here)  If for every action there is an equal and opposite reaction,
wouldn't you then be at pains to describe a significant, though brief,
reduction in the forward velocity of the wagon, and then also be
responsible to explain why the brief reduction in velocity was at an
end, and why it endured for only whatever length of time it did, and
the RATE OF CHANGE of velocity both during the onset of the brief
interval as well as during it's disappearance at the end of it?
   Would you then claim that while the athlete is airborne, the
halteres are causing him some measure of drag (paralleling
[metaphorically speaking] the rolling resistance of the wagon), thus
necessating his divesting himself of the disadvantage of them with
expedient dispatch, whereby the mere release of them would provide him
with a significant, albeit 'brief' impetus, thus affording him a great
leap forward?
   Methinks that Sir Isaac Newton would raise an eyebrow.

Greetings, hdubin!

Researchers are selected based on their excellent ability to Answer
your Questions, rather than ability to deride other Researchers'
Answers. I think you will find that tutuzdad has provided you with a
well-researched, well-documented, accurate Answer.

Best wishes!

aceresearcher

With respect, roadrunner. 

The question was raised by hdubin and for my money was rearched well
and thoroughly by Tutuzdad. As per the google answers pricing guide
some might actually say generously researched and the "theory" is one
reported on not supported by the researcher. Since theory is one of
the foundations of science it was completely within the frame of the
question to mention it.

To place an answer clarification within a comments box is not really
fair to either the researcher or the asker since the question was not
initially posed by yourself.

Therefore, with the greatest respect roadrunner, if you did have a
further question, you should really present this in the form of a
question as the terms and conditions of google answers does discourage
answering questions for free, it is after all a service.

Why not post your comment as a question put a fee on it and we may be
able to discuss it further.

Take care

Johnny Phoenix

To aceresearcher;

Thank you for your prompt response to the comment I posted a couple of
days ago.  I had hardly finished reading the first sentence when I
began to see the error of my ways.  I realized that not only was I
making a poor first impression, but I had willfully and arrogantly
*derided* someone who hadn't deserved it, but who was likely trying to
be imaginative with an example by simplifying a phenomenon into a word
picture with common images in it.  I apologize for my behaviour, and
have learned an embarassing lesson.

Thank you for being tactful.

roadrunner

To Johnny Phoenix;

Thank you for an equally prompt response (see above) to my misguided
comment.  I realize that whatever objection I may have had to whatever
I had read, I had no call to treat anyone in such an abrasive a
manner.  Furthermore I recognize that I was in error by my method, no
matter what the rationale may be.  As you rightly indicate, this part
of the forum is not a place for my dissension, but I may feel free to
raise my questions on my own dime, thus preserving the existing high
standards of this website.  Thank you for being so gentle with me in
your chastisement.  I would like someday to pose my own questions, but
I haven't any plastic money.

With respect,

Roadrunner

To Tutuzdad;

I'm sorry for mistreating you the way I did three days ago and I
apologize.  I was out of line for behaving in such a manner and I have
no excuse.  I feel fortunate that I wasn't responded to in a like
manner.  Those who corrected me were very accomodating of my feelings
and I learned more than had I been upbraided.  I am humbled in the
presence of such unflappability and feel undeserving of such
consideration.

Apologetically,

Roadrunner.