Asafa Powell's drug explained
The banned drug oxilofrine that top Jamaican sprinters Asafa Powell and Sherone Simpson have tested positive for is a stimulant used to boost the body's ability to burn fat.
The substance helps athletes boost their power-to-weight ratio with more lean muscle and less fat, and so increase their speed. It may also increase the rate at which the heart reaches its maximum performance during exercise, meaning a greater supply of oxygen can get to the muscles earlier.
Oxilofrine is an agent that stimulates part of the nervous system and was previously used to treat low blood pressure. More recently, it has started to appear in combination with caffeine in dietary supplements marketed as weight loss products.
However, the superiority of using oxilofrine over an exercise warm-up to achieve this appears unconvincing. There have been no previous findings in Britain but competitors in cycling, athletics, weightlifting, rugby union and American football have been banned in the last three years.