-class athletes and was pronounced clear of the most common banned substances in independent tests.To help you stay the course in top physical condition, this month we are giving 60 subscribers two tubs of 60 SportFlex capsules – together worth £17.98.For your

. If your BMI drops below 18.5, you're at risk of becoming weaker and slower. WEIGHT LOST 5K 10K HALF-MARATHON MARATHON 900g 12.4 secs 25 secs 52 secs 1:45 2.3kg 31 secs 1:02 2:11 4:22 4.5kg

successor, Usain Bolt, is not, but that is because he's 200ft tall and runs on wheels. How elite athletes' BMIs comparePaula RadcliffeHeight 5'7" Weight (kg) 54BMI 18.0 (Underweight) Haile GebrselassieHeight 5'4" Weight (kg) 56BMI 20.5 (Normal Weight

has been studying questions like this for more than 20 years, in between running 58 marathons (with a 2:37 PB) and ultra-marathons. He is also a doctor of public health and a professor of exercise science at Appalachian State University in the USA. I

nutshellOur 1400-article archive covers training, racing, injuries and health, shoe and gear reviews and buying advice. Our one aim: that the most nervous beginner and the zippiest racer alike will be able to find a useful answer to almost any running

Vitamins are essential for good health. This much we can agree on, but then things quickly become murky. There is so much information, contradictory research and advertising out there about the vitamin needs of endurance athletes, and how

of nutrition, it ranks foods based on their effect on blood sugar levels.The rise in sugar levels is graded from 0 to 100; the higher the number, the faster the absorption of carbs. Foods such as oatcakes, strawberries and cashew nuts have a low GI (under 55

, I have calculated the correlation for the ‘over two years' experience’ group. The correlation came out as -0.342. A perfect correlation would be +1 or -1. We therefore cannot say that increased running will always lead to reduced stress, but we can

and decrease levels of C-reactive protein in the blood, which is a marker of inflammation. "Cocoa powder contains no added sugar and, compared with dark chocolate, less saturated fat," says Susan Kleiner, author of Power Eating (Human Kinetics, £13.99).Eat

, as in lowered mortality and heart-disease risk. Which isn’t to say walking does nothing for you (it does). Running simply does more, as two major studies have proven recently:Regular vigorous activity reduced mortality risk significantly among 17,000 men