The Evolution of High Jumping Technique: Biomechanical Analysis Jesús Dapena Department of...

The Evolution of High Jumping Technique:

Biomechanical Analysis

Jesús DapenaDepartment of Kinesiology

Indiana UniversityU.S.A.

adapted from the Dyson Award Lecture at the XX International Symposium on Biomechanics in Sports Cáceres, Spain, 2002

There was no high jumping event in the ancient Greek Olympic Games.

High jumping seems to have its origin with the Celts (Tailteann Games).

But modern high jumping began in Germany in the late 1700s.

It started as a physicaleducation activity forchildren.

from GutsMuth, 1797

Then it developed into a competitivesport in England in the early 1800s.

And soon after, it spread to Canadaand the United States.

To clear a high jump bar, it is necessary to drive the center of mass (c.m.) of the athlete to the largest height possible.

basic principles of high jumping:

It is also necessary to move the body in the air in a way thatwill allow the athlete to clear a bar set as close as possible tothe peak height reached by the c.m.

bar height cleared

peak heightreached by centerof mass (c.m.)

effectiveness ofbar clearance

For a given peak height of the c.m.,lowering some parts of the body makesother parts of the body go higher.

This is the mechanical principle thathigh jumpers have used to improve theeffectiveness of the bar clearance.

Techniques have progressed a lotsince the beginning of modern highjumping around 1800.

And every new technique was namedafter an improvement in the bar clearance.

Let’s look at this progression in thebar clearance technique.

progression of bar clearance effectiveness

(no technique) legs-up

~1800

If a high jumper remains in a straight vertical position aftertaking off from the ground, the height of the bar that thefeet can clear will be far below the peak height of the c.m.

By lifting the legs, the trunk and head get lower,and the c.m. stays at the same peak height as before. But the athlete can clear a higher bar.

scissors

The next technique in the evolution of high jumping was the “scissors”, in which the legs are lifted over the bar in alternation one after the other. The advantage of the scissors technique is that parts of both legs are below the level of the bar at the peak of the jump. This increases the height of the pelvis, and therefore the bar height that can be cleared.


legs-up scissors

~1874

eastern cut-off

The scissors was followed by the “eastern cut-off” technique (sometimes called the Lewdenscissors in Europe). In this technique the athlete rotates the trunk into a horizontal positionat the peak of the jump. This lowers the trunk, and therefore lifts the pelvis higher than in the simple scissors technique. The result is a higher bar clearance. A disadvantage of the Eastern cut-off is that it requires tremendous flexibility.


scissors

~1892

eastern cut-off

western roll

The eastern cut-off was succeeded by the “western roll” technique. In this technique theathlete cleared the bar on his/her side, with the takeoff leg tucked under the rest of thebody. This technique probably did not improve much the effectiveness of the bar clearancein relation to the eastern cut-off. However, it also did not require very much flexibility. Thus, the contribution of the western roll was to provide a reasonably effective bar clearance for a larger number of high jumpers.


eastern cut-off

~1912

western roll

straddle

The western roll was followed by the “straddle” technique. In this technique the athletecleared the bar face-down, with the body stretched along the bar. The straddle allowed parts of the legs to be lower than the bar at the peak of the jump. This allowed the pelvisto rise to a greater height in relation to the position of the c.m., and therefore improvedthe effectiveness of the bar clearance.


western roll straddle

~1930

While the straddle was replacingthe western roll, importantinnovations were occurring inthe run-up and in the takeoff:

improvements in run-up and takeoff:

fast run-upSome athletes used a fast run-up. This allowed them to put themuscles of the takeoff leg in fast eccentric conditions during thetakeoff phase, which in turn allowed the athlete to exert a largervertical force on the ground.

*

* (In “eccentric conditions” the muscles are forced to stretch while they are trying to shorten. In such conditions the muscles can make very large forces.)


fast run-up

low position at end of run-upOther athletes ran with the c.m. in a low position in the laststeps of the run-up. This allowed them to have available a longvertical range of motion for the c.m. during the takeoff phase. This increased the height of the jump.

close to vertical at end of takeoff


fast run-up

low position at end of run-up

Some athletes noticed that a vertical position of the body atthe end of the takeoff increased the height of the jump. Thiswas also due to an increased vertical range of motion duringthe takeoff phase.

double-arm action



fast run-up


Other jumpers moved their arms into a backward position in the last steps of the run-up, and then threw them stronglyforward and upward during the takeoff phase. This allowedthe takeoff leg to exert a larger force against the ground.

double-arm action



fast run-up


straight lead leg actionStill others kicked forward and upward with the lead leg duringthe takeoff phase, with a motion similar to a soccer kick:

This “straight lead leg” action had the same purpose as the double-arm action, but with an enhanced effect due to the larger mass and length of the leg.

Today we know that all these actions areadvantageous for the generation of lift in a high jump.

However, this was not clear in the 1940’s and early 1950’s. There were disagreementsabout what was advantageous, what wasdetrimental, and what was neutral.

As a result, only a small number of high jumpers incorporated one or another of theseelements into their techniques, and nobodyused all of them.

1956

Charles Dumas (USA)2.15 m (7’ 0-1/2”)

The United States dominated the men’s high jump event during the first half of the 20th century. Following this tradition, in 1956 Charles Dumas raised the world record to 2.15 m, and then proceeded to win the Olympic Games at Melbourne.

But things were about to change …

“The ussians are coming!

The ussians are coming!”

In 1957, Yuri Stepanov of the Soviet Union broke Dumas’ world record with a jump of 2.16 m.

It was found out later that Stepanov had used a “built-up”takeoff shoe with a very thick sole. This increased the verticalrange of motion of the c.m. during the takeoff phase, and thusgave an advantage to the jumper.

But the rules current at the time did not limit the thickness of the sole, and therefore Stepanov’s jump was legal. The International Amateur Athletic Federation soon changed the rules, and limited the maximum thickness of the shoe sole to 13 mm. However, the rule was not made retroactive, and Stepanov’s record was allowed to stand.

In 1960, things seemed to go back to “normal”. John Thomas reclaimed the world record for the United States, and raised it to 2.23 m.

He was the overwhelming favorite for the gold medal at the Olympic Games to be held at Rome later that year ...

Olympic Games

Rome, 1960

#1Robert Chavlakadze

(Soviet Union)

#2Valeri Brumel(Soviet Union)

Rome, 1960

#3John Thomas

(USA)

Surprisingly, Thomas was relegated to third place in the 1960 Olympic Games at Rome by two athletes from the Soviet Union, Robert Chavlakadze and Valeri Brumel

… and by 1963 Brumel had raised the world record to 2.28 m.

It became clear that there was more to Russian high jumping than Stepanov’s built-up shoe!

But to a great extent they were also due to the work of theSoviet Union’s national high jump coach, Vladimir Dyachkov.

In part, the improvements of the Russian high jumpers weredue to advances in physical conditioning methods.

Dyachkov had studied films of the world’s best high jumpers for many years. Through his analyses, he was able to figure out the advantages and disadvantages of the various techniques used by high jumpers.

He acquired a particularly good understanding of the advantages provided by the run-up and takeoff improvements that had been gradually introduced during the 1940’s and 1950’s.

Dyachkov incorporated practically all of them into the technique of every one of his athletes.

Before Dyachkov, one or another of these advantageous technique elements had shown up sporadically in the techniques of various high jumpers.

dive straddle

A new variant of the straddle appeared around 1960. It was called the “dive straddle”. In this technique, at the peak of the jump the athlete’s trunk was set at an oblique angle with respect to the bar. This allowed the athlete to drop the head and upper trunk below the level of the bar at the peak of the jump. This raised the hips and the rest of the body, and therefore allowed the athlete to clear a higher height than with the older (“parallel”) straddle. Dyachkov adopted this bar clearance technique for his jumpers.


straddle dive straddle

~1960

So by the mid-1960s high jumping techniqueseemed to be well understood.

Dyachkov had figured it all out!

a fast and low run-up, with preparation of the arms in the last one or two steps, followed bya double-arm action and straight lead leg action that ended in a vertical position of the athlete at the end of the takeoff. The athlete cleared the bar using the dive straddle technique.

What was needed was:

It is important to point out that not all high jumpers adapted well to this technique.

Some athletes were not able to combine effectively a straight lead leg action with the impulse of the takeoff leg. These bent-lead-leg jumpers were quite frustrated, incapable of jumping properly.

My interest in high jumpingstarted at about this time.

J.D. Sr.

My father had been a high jumper when he was young. He used the technique of his day, the eastern cut-off.

He took me to many track meets as a child. I liked the sport, and eventually I also became a high jumper (low jumper??). I used the technique of my day, the dive straddle.

J.D. Jr.

A completely new technique appeared in the mid-1960’s. It was invented independently by several different jumpers who took advantage of the increased safety provided by foam-rubber landing mats.

In 1968, Dick Fosbury won the American University (NCAA) Indoor and OutdoorChampionships using this technique.

Today this technique is called the “Fosbury-flop”. These athletes made the bar clearance on their backs, with the body horizontal and perpendicular to the bar.

Later that year, Fosbury competed at the Mexico City Olympic Games. And the winner was …

Olympic Games

Mexico City, 1968

#1 Dick Fosbury (USA)

Until Fosbury’s win at the 1968 Olympic Games, there had been little information on this jumping style. But the Games were televised live, world-wide. The high jumpers and coaches in the audience were able to see the new technique in great detail.

It became clear that the bar clearance was not the only difference between the “standard” dive straddle and the Fosbury-flop: Fosbury’s run-up was curved, and his arm and lead leg actions during the takeoff phase were weaker than in the straddle.

The day after the 1968Mexico Olympic Gamesevery high jumper in theworld tried the Fosbury-flop.

They imitated Fosbury’s curved run-up, even though they did not know why --or if-- the curve was needed.

But most of them added a double-arm action and a straight lead leg, since these were regarded as basic elements for any high jumping technique.

However, this did not work: They found it impossible to attain at the peak of the jump the desired face-up position, perpendicular to the bar.

These athletes had to give up on the Fosbury-flop.

On the other hand, the bent-lead-leg high jumpers (remember them, the ugly ducklings?)adapted to the Fosbury-flop with little trouble.

This led to the separation of the world’s high jumpers into two groups: those who used the straddle and those who used theFosbury-flop.

These were the differences in their techniques:

straddle Fosbury-flop

bar clearanceon the stomach

bar clearanceon the back

straight run-up curved run-up

strong double-arm actions,and straight lead leg

weaker arm actions, andbent lead leg

fast run-up even faster run-up

The Fosbury-flop raised importantquestions:

What advantages did the curved run-upprovide?

Was the bar clearance more effective thanin the straddle?

Why was it so difficult to do a Fosbury-flop with a straight lead leg?

And how could a technique that used abent lead leg be good??

Answering these questionswas what I set out to do inmy research.

What advantage did the curvedrun-up provide?

Some popular theories:

(1) The curve allowed the athlete to use “centrifugal force” to get more lift.

This made no sense at all. Centrifugal force is a horizontal force, and therefore can’t provide lift.

(2) The curve allowed the athlete to start the rotation already during the run-up, and thus allowed the athlete to concentrate exclusively on getting lift during the takeoff.

This had some potential, but ultimately was alsoshown to be wrong:

What I found:

In the Fosbury-flop, the rotation was notgenerated during the run-up; it was generatedduring the takeoff.

Here is how the curve was useful:

The curve permitted a low position at theend of the run-up without having to runwith very bent knees.*The curve also helped to prevent the athletefrom leaning excessively toward the bar at the end of the takeoff.*

Was the bar clearance moreeffective in the Fosbury-flop thanin the straddle?

Yes.

The Fosbury-flop had an advantage of about5-7 cm (2-3 inches) in the effectiveness of thebar clearance with respect to the straddle.

Let’s take a look at this graphically:


dive straddle

~1967

Fosbury-flop

The Fosbury-flop also had a disadvantage ofabout 5 cm (2 inches) in the height of the c.m.at the end of the takeoff.

This was because in the Fosbury-flop the armsand the lead leg were in lower positions at theend of the takeoff:

However …

Straddle Fosbury-flop

Therefore, the Fosbury-flop had a moreeffective bar clearance (an advantage), but alsoa lower height of the c.m. at the end of thetakeoff (a disadvantage).

To a great extent these two factors cancelledeach other out.

So overall there was no net advantage for eithertechnique with respect to these two factors.

Why was it so difficult to do aFosbury-flop with a straight lead leg?

The double-arm swing and the straight leadleg action are backward (counterclockwise)rotations …

… so they favor the generation of thecounterclockwise rotation generally neededin the air for the straddle bar clearance.

However, in the Fosbury-flop this would notbe good, because for the Fosbury-flop youneed to make a clockwise rotation in the air.

This is why Fosbury-flop high jumpers needto use weaker actions of the arms and ofthe lead leg during the takeoff.

And how could a technique thatused a bent lead leg be a successfultechnique??

Because the Fosbury-flop jumpers compensatedfor the bent lead leg with the use of a faster run-up.

If the athlete ran fast enough, the actions of thearms and of the lead leg became less important.

In effect, what counted was the combination ofthe run-up speed and the actions of the swinginglimbs.

… and different combinations were optimalfor different athletes.

For Fosbury-flop high jumpers the optimumwas at a combination of very fast run-upspeed, and rather weak arm and lead legactions.

For straight lead leg straddle high jumpersthe optimum was at a combination ofslightly slower run-up speed, but strongerarm and lead leg actions.

Why wasn’t one of these techniques good foreverybody?

Nobody knows for sure, but it was probably dueto physiological differences in the muscles of thetakeoff leg.

In the Fosbury-flop the takeoff leg flexes quickly,and then extends quickly.

In the straddle the takeoff leg flexes moreslowly, stays flexed for a longer time, and thenextends more slowly than in the Fosbury-flop.

Some people’s muscles seem to be suited betterto the first kind of action, and other people’smuscles to the second.

The choice of arm and lead leg actionswas the first decision.

For the athletes with the weaker freelimb actions, the Fosbury-flop type of barclearance.

For the athletes with the stronger freelimb actions, the straddle type of barclearance.

This first choice then determined whatkind of bar clearance would work thebest for that individual:

So the bottom line is:

For some jumpers the Fosbury-flopwould be the best technique

… while for other jumpers the straddlewould be the best technique.

Therefore, today both techniques shouldbe in use

… but they are not.

Only the Fosbury-flop is being used today;the straddle has disappeared.

The crucial factor was that the Fosbury-flop was much easier to learn than thestraddle.

So today, all high jumpers use theFosbury-flop technique… even though the straddle probablywould be better for some of them.

The End

The Evolution of High Jumping Technique: Biomechanical Analysis Jesús Dapena Department of...

Documents

Transcript of The Evolution of High Jumping Technique: Biomechanical Analysis Jesús Dapena Department of...