Oscar Pistorius. My Thoughts.

Written 7/2/08


Example 1: Wheelchair Marathon

First, an example of an athletic competition where disabled athletes perform better (i.e., faster times): the wheelchair marathon. The wheelchair allows the athlete to move at a higher speed and at a superior energetic cost of transport. The wheelchair can be thought of as a passive orthotic device, and although it may be a poor orthotic for many terrains (uphill, grass, uneven surfaces, etc), it is a very good orthotic for a marathon road race and provides a huge competitive advantage over an able-bodied runner.

Example 2: Leg Length

Who is to say how long our legs should be? Individuals of the same height may still have very different leg lengths. Prothetic legs allow an individual to arbitrarily set the length of his legs. For certain races, it may be advantageous to have longer legs, which would therefore facilitate a longer stride. Perhaps this could provide a significant advantage over able-bodied athletes who have no control over their own leg length.

Example 3: Leg Mass

The shank (lower part of the leg below the knee) and foot are made up of bones, muscles, tendons, ligaments and other tissues. Therefore, the shank/foot have some finite mass that must be carried along with the rest of the body during any type of locomotion. If you design a prosthetic shank/foot weighing less than the natural limb, you have successfully reduced the load that must be carried by the individual; thereby giving an advantage to the athlete who is carrying the lighter load.

Example 4: Metabolic Energy

The human body consumes internal metabolic energy in order to generate the mechanical motion, forces necessary to locomote. In vigorous athletic competitions, such as the 400m dash, much of the metabolic energy must come from anaerobic pathways since aerobic (oxygen) pathways are not fast enough to keep up with the body’s intense energy consumption need. The drawback to anaerobic energy is that it is exhausted very quickly; then your cells need rest in order to replenish the resources needed to fuel the anaerobic activity. In the case of a passive mechanical device such as the Cheetah prosthetic foot, the athlete’s affected limbs are no longer bounded by this anaerobic metabolism limitation. There is no graded decline in energy/performance capability in the prosthesis as there likely is in the natural limb -- in this sense its potentially advantageous to use the prosthetic feet.

Again, these simple examples are meant to spark thought and conversation. They are not fully investigated or formal scientific arguments, nor am I using them as a basis to make any conclusions about running prostheses.

In conclusion, I cannot say anything definitive about the present advantages/disadvantages of running prostheses. The reality is that presently we do not know enough about our own bodies to make a conclusive scientific comparison, nor is there an agreed upon method or protocol for quantifying the net advantages and disadvantages of using a prosthesis. I will however say this: the human leg is designed to do many different tasks -- running, walking, jumping, skipping, spinning, cutting, etc. Fundamentally, if we just want to design a leg/foot for a single task (such as running), there is no reason to believe that we cannot create a prosthesis that is better or more efficient than the human leg. Whether or not the technology is currently available, whether or not it can be accomplished passively (no active electromechanical components) and whether or not we can effectively couple/integrate this prosthesis with the human body are yet to be determined. But in theory, there is no reason to believe we cannot achieve a superior prosthetic running leg/foot.

In the near future, I fully expect the prosthetic technology to advance beyond the capabilities of the natural, biological limbs. Prostheses can constantly be upgraded, using the newest, best actuators, sensors and materials. Prosthetic limbs will not be bound by biomechanical or physiological limitations related to power or speed or metabolism or fatigue. Similar views have been expressed by leading experts in the fields of biomechanics and prostheses. MIT professor Hugh Herr led the most recent (IAAF/CAS sanctioned) investigation of Pistorius and the Cheetah feet; ultimately leading to a reversal of the previous IAAF Pistorius ban. Nevertheless, Herr has publicly stated that within 20-30 years, he predicts the Paralympics will be faster than the Olympics (60 Minutes, September 2007). To the Boston Globe he further commented that ``Even today, some people pity those with disabilities. In the future, [the disabled] will be physically more capable. And then, being physically unique will no longer inspire pity. It'll be unique. And even sexy."

I would love to discuss these topics at further length. If you have any comments, feedback or questions, please email me at kzelik@umich.edu. Although not included in the descriptions above, I would also be happy to go into further scientific detail about how Oscar and the running prostheses are evaluated, what the scientific evidence indicates so far, maybe more importantly what the research does not say and also why it is so difficult to conduct accurate, meaningful and conclusive research on intact versus amputee running.

External Links

Court of Arbitration for Sport: Official Decision

IAAF Release - January 14, 2008

The Science of Sport Blog

ESPN Release - CAS Decision, Video


A double-leg amputee since infancy, Oscar Pistorius (“the fastest man on no legs”) has run the 400m dash in 46.56 seconds, just one second off the Olympic qualifying standard of 45.55 seconds. In a culture where disability bears a connotation of inferiority, this accomplishment is almost unimaginable. In my book, Pistorius is one of the greatest competitors of our time (along with Kobayashi, Lance Armstrong and Michael Jordan). To overcome such adversity, to persevere and to become such a tremendous quarter-miler...in one word, AMAZING. But should he be allowed the opportunity to try to qualify for the Olympic Games? To compete against able-bodied athletes?

Its easy to come up with reasons why an amputee might be at a disadvantage in running (or any athletic competition). Its hard NOT to empathize with Oscar’s struggle, with his incredible story.  But for scientists, this controversy has brought to the forefront some very fundamental, yet heavily debated questions:

- in sport, what exactly constitutes an “advantage”?

  1. -could an amputee actually hold an “advantage” over an able-bodied athlete?

  2. -does current prosthetic foot technology provide an “advantage” for the amputee?

  3. -how do you go about measuring or quantifying an “advantage”?

In track and field, how could it possibly be an advantageous to be an amputee?! Outrageous, right? Well, this is the question I am most often asked. My objective below is NOT to argue for or against the scientific evidence that has been presented to the IAAF, IOC or CAS -- because quite frankly I do not know the correct answers. Rather, my objective is to present some simple, intuitive examples that may help you see a different perspective, and perhaps better understand why this is such an intriguing and heavily-disputed topic.




Pistorius Update: July 2, 2008

With the Olympic games about a month away Pistorius is running out of time to qualify -- no pun intended. He competed in Milan, Italy earlier today (7/2), but only ran 47.78 seconds, well off the Olympic A Standard (45.55 seconds) that he needs. He has two more meets to try to qualify, July 11 in Rome and July 16 in Switzerland. He himself admits the 2012 Olympics are a more realistic goal. In all likelihood he will not qualify for the 400m individual event; however, if he can improve in the next two meets he may have chance to compete as a part of the South Africa 4x400m relay team. Also, to put his performance in perspective, he is one of the top quarter-milers in South Africa, but in the U.S. he would not have qualified to participate in the Olympic Trials (top 28 U.S. competitors).

AP Release on Pistorius’s race in Milan

US Olympic Trials Qualifying Standards