Finding his feet

The name is an obvious takeoff from the 1982 Hollywood science-fiction cult classic

Blade Runner,but there it refers to a special police operative assigned to hunt down genetically engineered organic robots called replicants

THE BLADES

Flex-Foot Cheetahs are manufactured by Ossur,an Icelandic company,and have been worn by amputees since the late 1990s but none have approached Pistoriuss speeds

In 2007,the IAAF sought to bar Pistorius on the ground that Cheetah blades are springs,but a court of arbitration ruled that a natural human leg is itself a spring

Fox-Foot Cheetahs are neither bionic nor motorised,but they have passive-elastic springs designed to emulate biological legs

Socket

The leg fits into a sock and snugly rests into a carbon fibre composite socket

Attachment

The connection between the foot and the socket is high enough on the back of the socket to accommodate a long foot

Foot carbon composite

The entire curved component is called a foot; there are spikes on the underside of the tip

ABLE-BODIED vs AMPUTEE
1. Burst from the blocks

Pushes off using feet,hips and calf muscles. Keeps legs tucked under torso to stay low and produce as much power as possible.

Must immediately stand up to start running. Hips produce all the force to to bring the knees up to the chest.

2. The stride

Power-producing contractions

Energy-absorbing contractions

Stabilising contractions

Hip muscles help stabilise the knee and generate speed. Pistoriuss hip has been described as a giant,giant engine.

Quadriceps,knee,calf and ankle work together to absorb energy.

Blade compresses,storing energy. Pistorius cannot stiffen his Cheetah blades just before contact,the way an able-bodied runner can with his lower legs. They are softer,so his blades are in contact with the running surface longer. He compensates by repositioning his limbs faster than most others.

Stride vs stride Pistoriuss website quotes IAAF spokesman Nick Davies as confirming that Pistoriuss stride length was the same as that of his nearest competitor in Rome in 2007. It cites studies as demonstrating that Pistorius takes shorter strides than his non-amputee competitors.

3. Mid-stance

Power-producing contractions

Stabilising contractions

Nearly all the leg muscles create a forward force.

Hips must generate nearly all the contractions of an able-bodied sprinter.

Knee begins to extend up while the ankle is pushing off.

Stored energy in the blades reaches the front edge.

Limb vs limb Single amputees cant transmit as much force on the ground with their artificial limb as they can with the biological leg; double amputees cant transmit as much force with either leg,as per studies cited on Pistoriuss site.

4. take off

As the foot pushes off,the lower leg generates more than twice the energy that was stored when the foot struck down.

Energy in the blade releases like a spring,propelling the runner forward. Only 80 of the energy stored in the compression phase is released.

Leg swing time Pistoriuss website says studies on 100m in Beijing Olympics show Walter Dix bronze ran with a leg swing time of 0.274 sec; faster than Pistoriuss swing time of 0.297 sec while winning 100m in Paralympics.

PISTORIUS vs OTHERS

45.07 sec

Pritoriuss best in 400 metres

2.4kg,a Cheetah blade and its hardware combined,compared to 5.7kg for the intact leg and foot of someone of Pistoriuss build

0.28 sec Time needed by Pistorius to reposition his limbs,20 faster than most athletes with intact limbs,as per study by two us professors

0.34s Average limb-repositioning times of Ben Johnson,Carl Lewis,Maurice Greene,Tim Montgomery and Justin Gatlin

15.7 Thats how much faster Pistorius is than these five in repositioning limbs

11.9 sec Pistoriuss advantage over the five sprint legends over 400m,according to a calculation by Peter Wyeand and Matthew Bundle,the profs who did the study

43.18 8211; 11.9: Would Weyand and Bundle predict that Michael Johnson 400m world record-holder would run 31 sec if he had both legs amputated? Hugh Herr of MIT

45.07 11.9: would pistorius,unaugmented,need 57s to run 400m,making him a non-factor? weyand says yes

Factfile

Born: November 22,1986,in Johannesburg

Hometown: Pretoria

Uniqueness: Born without a fibula in either leg. The fibula runs between the knee and the ankle,beside the Tibia

Age 11 months: Both legs amputated just below the knee

13 months: Fitted with prostheses

17 months: Starts walking

2004

Jan 1: First sprint session

Jan 28: First competitive 100m race for Pretoria Boys High School,time of 11.72 seconds

June: Invited to US for trials of Flex-Foot Cheetahs

September: Paralympic medals T44 200m gold in world-record 21.97 seconds; T44 100m bronze in 11.16 seconds

2005-06

More success in events for amputees,also contests events for able-bodied athletes

2007

March: 400m in 46.56 sec at South African Championships

March 26: IAAF Council introduces amendment regarding technical aids

July 13: Finishes second in the Golden Gala event at the Olympic Stadium in Rome; IAAF installs HD cameras around track to analyse his running style

December 20: IAAF sends Pistorius report saying he has an unfair advantage

2008

January 11: After Pistorius responds,IAAF ratifies decision to ban him from all able-bodied athletics competition findings were that his bouncing locomotion was an advantage and that he required less oxygen and fewer calories than able-bodied runners going at the same speed

May 16: Court of Arbitration rules in Pistoriuss favour,and that the data showed that he used the same oxygen amounts

September: T44 100m,200m amp; 400m Paralympic golds in Beijing

2010-11

More triumphs in both fields,the high point being the 400m gold against able-bodied rivals in Lignano,Italy,where his 45.07 sec qualified him for bigger events

2012

Selected in South Africa team for London Olympics

Compiled from NYT reports and http://www.oscarpistorius.com