These are the cells which carry oxygen around the body to keep tissues alive - a child with severe thalassaemia will become anaemic, fail to thrive, and, if left without treatment, can die in childhood.

BBC: Q&A: Test-tube lifesaver

The speed with which your body can clear the acid byproducts of metabolism and carry oxygen to your mitochondria are affected by cardiovascular training to be sure (confirmed), but there is a basic inequality set up by our very genetics.

CNN: Why Oscar Pistorius deserves to run