Science of running in black and white

Cape Town - Black athletes are known for their superior running and endurance when it comes to marathons regardless of weather conditions, but new research has shown that low levels of oxygen in the air may well be putting them at a disadvantage.

The study, published in the International Journal of Sports Medicine, was done by researchers from UCT and the Medical Research Council research unit for exercise science and sports medicine.

They found that while black and white runners seemed to perform similarly in normal oxygen levels, black runners did poorly when there were low concentrations of oxygen (hypoxic) in the air.

Physiological differences, including the size of their bodies and their ability to retain lactic acid (a molecule that contains fuel for the body) meant white athletes seemed to be more tolerant of hypoxic conditions than their black counterparts.

The study analysed a small sample of 14 black and white competitive South African marathon runners.

While researchers couldn’t ascertain why white runners outperformed black runners, they associated their better performance to the fact that white runners had bigger bodies, and high concentrations of lactic acid in their bodies compared to black runners.

Whites, however, had greater oxygen deficiency in their arterial blood. While low oxygen levels were associated with poor performance or potentially limiting for athletes, in this study researchers were puzzled to observe a better performance among whites despite their significantly lower oxygen levels.

Lead researcher Dr Jordan Santos-Concejero said the results suggested “a remarkable tolerance” in white runners to the lack of oxygen, not matched by black runners.

“This may be due to difference in oxygen delivery in the tissue.”

While blacks were found to have low lactic acid levels, they achieved a higher heart rate during the fatigue-resistance runs.

Despite their poor performance, black runners presented high oxygen saturation in their bodies at 72 percent compared to only 64 percent of white runners.

Additionally, recovery period after a fatigue-resistance test was significantly lower in the black runners than in white runners.

Santos-Concejero said while the specific mechanisms for this apparent performance advantage for whites in poor oxygen levels remained unclear, the study demonstrated “for the first time that performance-matched black runners display performance and altered sensitivity compared to white runners during running in hypoxic conditions”.

But Santos-Concejero cautioned against applying his findings to the elite African runners, including those from Kenya and Ethiopia, who had a prenatal and chronic exposure to high altitude, where there was less oxygen in the air.

sipokazi.fokazi@inl.co.za

Cape Argus

• DNA profiling helps athletes peak

• Burst of energy behind world's fastest man

• Barefoot running theory put to the test

• Creating the super soldier