Locally developed algorithm to ensure Sanlam Virtual Cape Town Marathon “fair play”

Running a marathon will leave you breathless, but running that distance at altitude, where there is less oxygen in the air, will leave you positively gasping for breath!

So, the application of an altitude factor to the Sanlam Virtual Cape Town Marathon on Sunday (October 18) will play an important part in ensuring “fair play” for the elite athletes participating in the race. Elite events are taking place simultaneously in Cape Town, Pretoria and Potchefstroom.

Sports Science Institute of South Africa’s Prof Ross Tucker has provided the race organisers with an algorithm which will allow times set by athletes in Potchefstroom and Pretoria to be compared directly with those achieved in Cape Town. 

 “There are scientific models that describe how performance is negatively affected by altitude for situations where people travel from sea level to altitude and then either compete right away or adapt for a short period (1 to 4 weeks) before competing,” explained Prof Tucker. “However, there are no models for what happens in people who are permanently adapted to altitude, or who have lived at altitude for their whole lives.”

“It is known that altitude natives are affected far less by altitude than sea level natives. Therefore, all the known models had to be adapted to make a valid prediction for Pretoria and Potchefstroom, under the assumption that the athletes running there would be altitude natives and adapted to altitude as a result.

“If this adjustment is not done, then all the models will vastly over-estimate the typical effect of altitude on performance and give too much of a handicap to the altitude events. So we eliminated models that are too aggressive or too conservative, and concluded with a model that lies between these extremes for race use.

“To develop a (theoretical) model it is possible to estimate, from first principles, how performance would be affected as altitude increases.  This method uses the known finding that VO2max (maximum uptake of oxygen by the athlete) increases linearly above 300m, and that a certain physiology is required to run a marathon in a given time.”

Prof Tucker and his team then ‘ground-truthed’ the theoretical model with a ‘real world’ application by comparing Kenyan athletes’ best 5km, 10km, half marathon and marathon times run at altitude and their corresponding sea-level performances within a two year period. These ‘real world’ data were then fed back into the models to calculate the implications for marathons and determine best outcomes for use in the Cape Town Marathon on Sunday.

Prof Tucker found that using a ‘first principles model’ a 2 hr 10 min 00 sec marathoner should be given a 5 min 31 sec handicap at altitude.  The Kenyan ‘real world’ method reduced this to just 1 min 33 sec.

An interesting example is that of former South African marathon record-holder, Bernard Rose, whose 2:14:45 win at Sun City, at the time the fastest marathon in the world recorded at altitude, compares with his best at the coast of 2:12:10 at the Peninsula Marathon.

Recognising that Kenyan athletes are ‘super-adapted’ to altitude, likely beyond that of South Africans living at altitude, Prof Tucker’s new combined model provides for a 3:30 handicap for a 2:10:00 athlete running at altitude and a 4:19 for a 2:40:00 marathoner. The same factor applies for Pretoria and Potchefstroom, with both cities situated 1340m above sea level.

Podium positions and prizes will be awarded to leading athletes across the line at each of the three venues, but the most prestigious award will be the “best overall performance” of athletes from all three centres, corrected for altitude using Prof Tucker’s algorithm.

Prof Tucker and his team did not stop at altitude, however.  In the interests of levelling the playing fields still further, they analysed the parameters of each course with respect to twists and turns.  A right-angled, and even more so a 180 degree turn around can cause an athlete to lose rhythm and time.  The course in Potchefstroom was judged to be approximately 90 seconds slower than the Cape Town one, with Pretoria approximately a minute slower than Cape Town.

Course differences and other uncontrollable variables, such as weather on the day, will not impact on the calculations for best performance, however, but will provide interesting talking points and will likely feature prominently in the commentary team’s patter on Sunday.

The race will be televised live on SABC 3 and will also be live-streamed to Africa and the world through the Sports Network Africa streaming site, spnafrica.com

Model for use in Cape Town Marathon

For typical men’s performances

For typical women’s performances