Sex Machine

Should you snog before you jog? Athletes traditionally abstain from sex before big competitions. Muhammad Ali wouldn't do it from six weeks before a fight, while footballers in the 1970s adopted the mantra: 'Nothing after Wednesday if you're playing on Saturday.' New evidence suggests, however, that the celibate may be missing out on athletic benefits. Here's the lowdown on why you should nip upstairs for a quickie the night before your race...

All about chemistry

Testosterone is the hormone both of sexual desire and competitive aggression. But does sex really deplete your reserves, as athletes have traditionally feared? Rubbish, says Emmanuele Jannini, Professor of Endocrinology at the University of L'Aquila, Italy. In fact, pre-race sex can give you a hormone high: Jannini's studies have proven that sex raises testosterone levels, which boosts competitive spirit. Jannini's prescribed dosage? "Complete, satisfactory sexual intercourse the evening before race day."

Girls on top

There's even better news for female runners. According to research at Rutgers University in the US, sexual stimulation in women creates powerful pain-blocking effects that could help to sooth post-run muscular pain. It is thought that this is because female sexual arousal blocks the release of a pain-transmitting neuropeptide called substance P. Israeli physician Alexander Olshanietzky took this theory one step further, claiming that female runners and high jumpers also experience an energy boost after sex. "The more orgasms, the more chance of winning a medal," he famously claimed before the Atlanta Games in 1996.

Calorie count

There's no need to worry about sex zapping your energy before a race. Scientists say that the average bout of nookie expends a similar number of calories as climbing two flights of stairs. This means that "sex the night before does not affect strength, endurance or the capacity to utilise oxygen", according to Dr Ian Shrier from the Department of Family Medicine at McGill University, Canada. He points to one study in particular, in which male athletes were made to run on a treadmill 12 hours after having had sex. They showed no decline in stamina, or mental and physical performance.

On the brain

Although little is known about the psychological effects of sex on athletic performance, many believe it stimulates a mental buzz. Sports therapist Anna Couser agrees: "I advocate athletes indulging in sex the night before a big event. They should be as relaxed as possible, as this allows them to perform better under pressure." After winning the US 10K title in 1993, American three-time Olympian Lynn Jennings attributed her victory, in part, to having had sex the night before. She claimed that it had "solidified [her] core feeling of happiness".

Sexual healing

Sex can also help you sleep - if you're a man, at least. The male orgasm induces relaxation and sound sleep, boosts the immune system and helps to repair damage to muscle tissue. This, together with the cocktail of endorphins and serotonin that are also released during sex, means that athletes are more likely to wake up feeling energised, optimistic and balanced.