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The science behind the perfect discus throw

The science behind the perfect discus throw
10 Apr
8:05

Updated April 11, 2018 13:24:37

Dani Stevens is at the peak of her athletic career and is now just centimetres shy of a mark that only a select few in women’s discus have achieved: throwing 70 metres.

Since 1993, only four women have done it.

To add her name to the list, Stevens, a former world champion, will need to squeeze every last ounce of power from her body to deliver the perfect throw at the Commonwealth Games.

It starts with the wind up.

The 29-year-old’s great range of motion already gives her an edge here. Her flexibility through her hips and shoulders allows her to move the discus well behind her back.

This movement is creating and storing elastic energy that she can maintain through her action and into the throw.

Another of Stevens’ strengths lies in her technique. Her drive to refine every aspect of her throw has resulted in a model throwing action.

“The whole time we’re working on technique, it’s not just going through the motions and trying to throw something a long way, it’s working really specific, small angles to try to get the biggest result out of the throw,” Stevens said.

The result is a throw that looks effortless but the movements are powerful and precise.

Her right foot sweeps around the circle. She’s trying to keep her leg ahead of her body to build up angular momentum.

Mike Barber, high performance coach with Athletics Australia, likens the action to a whip. Short movements close to the body, that result in “fast velocity at the end” as the body unwinds.

99 times out of 100 Dani lands perfectly in the centre of the circle. “My coach will tell me if I am not,” Stevens said.

Again Dani’s flexibility is important here as she plants her front foot, she wants her hand to be as far back as possible.

“The quicker she gets it down, the further back that hand is, which means she got a lot of path to accelerate the hand through the delivery,” Mike Barber said.

This final position as the discus is launched skyward is known as the block.

Dani uses all her power in her non-throwing side to abruptly halt the momentum of the action. This helps to drive all the force she has generated up through the, hip, shoulders and into the throw.

“It’s like a car crash, you hit the brick wall with your left side and the right side accelerates past it and that takes a lot of strength to be able to do that,” Barber said.

With a throw around 69 metres, Dani is releasing the discus at 27 – 28 metres per second.

Most of that speed is generated in the last 0.1 second of the action.

The release speed, release angle, spin and height of release are key factors in a good throw.

Too steep it’ll stall, just like an aeroplane, too flat and it won’t get the aerodynamic lift needed.

The ideal release angle is between 37 and 42 degrees.

For Stevens, the magic mark is 38 degrees.

But even that needs to be adjusted depending on weather conditions.

It’s a lot to think about for actions that can take just milliseconds to complete.

But if all goes to plan this week, Stevens will become the first person in Commonwealth Games history to break the 70 metre mark.

Dani’s personal best is 69.64 metres, less than an A4 sheet of paper away from her goal. She threw that last year to win silver at the World Championships in London.

A throw that would have won her the last 12 World Championships and five Olympic titles.

Only four women have managed to throw over 70 metres since 1993.

In more recent times, Cuba’s Denia Cabellero threw a personal best of 70.65 metres in 2015 and Croatia’s Sandra Perkovic has recorded a number of throws over 70 metres with a personal best of 71.41 metres last year.

The world record of 76.8 metres is considered one of the most untouchable records in athletics. It was set by East Germany’s Garbriele Reinsch in 1988.

But even with all practise in the world, there will always be factors out of Stevens’ control.

Like many athletic disciplines, doping has left its mark on the sport.

Of the top 100 throws recorded in discus over the last few decades, 95 were recorded in the 1980s. A period dominated by athletes from the Eastern Bloc and in particular East Germany.

East Germany was later found to be running a large-scale doping program for many of its athletes.


Throws 70 metres and over since 1972

Dani Stevens’

best throw:

Throw Distance (m)

Throws 70 metres and over since 1972

Throw Distance (m)

Dani Stevens’

best throw:

For Stevens, an athlete who takes great care in her own nutrition and pride in her integrity, her uncompromising quest for Olympic gold has been hampered by others who’ve chosen to cheat.

Take the Final of the 2008 Beijing Olympics for example.

Stevens finished ninth, which meant she missed out on getting three additional throws.

In 2016, Cuban Yarelys Barrios was retrospectively disqualified from that final after testing positive for a banned substance and Stevens was elevated to eighth.

Stevens’ coach of more than 20 years Denis Knowles said if it wasn’t for doping, it would have been a very different story for Stevens in China.

“She should have won that Olympic Games,” Knowles said.

Some athletes might rightly feel disenchanted, but for the 29-year-old it’s more fuel to power her drive.

“That is the really rough side of other people choosing to dope but in the end it just fires me up even more,” Stevens said.

Stevens said she’s in the best condition she’s ever been.

“Everything for me is geared towards the Commonwealth Games and then we have the World Championships in 2019 in Doha and then pretty quickly after that we have Tokyo 2020,” she said.

“To be honest, my ultimate lifetime goal is 72 metres.

“I am very excited about these next three years.”

Credits:

Topics: commonwealth-games, sport, athletics, australia, qld

First posted April 11, 2018 06:01:48

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