Our national rugby and cricket players should follow the lead of Brazilian soccer star Ronaldo and make love the night before big games.
Not only are they likely to have a better chance of winning on the field, they are also likely to boost their immune systems.
Real Madrid striker Ronaldo has gone on record as saying he has sex with his wife Milene Domingues before every match, and believes it is the perfect way for top players to prepare for a big game.
Certainly, research backs up his view, and shows that a good sex life is an excellent method of keeping sportsmen in tip-top condition, in body and mind. It also makes them less vulnerable to colds, flu and other viruses.
Unfortunately, our rugby players in Australia and cricketers in Pakistan are without their spouses and girlfriends. In the case of the Proteas, apart from security considerations, it's because the tour is short, says United Cricket Board corporate relations manager Bronwyn Wilkinson.
The Springboks in Australia took the decision themselves to leave their women at home because "they want to concentrate on the game", says team manager Gideon Sam.
(Their concentration appeared to have been elsewhere when they played England on Saturday. Perhaps the outcome would have been more positive, if they'd been able to cavort between the sheets with wives and girlfriends the night before.)
Still, there's hope, as a few players' partners may join them before the match against Georgia on Friday, but most will be solo for the duration of the World Cup, says Sam.
"That's a real pity," says Dr Linda Friedland, "because sex is not only pleasurable and sustaining for a relationship, it has a potent effect on health and immunity."
Friedland is a Johannesburg physician who specialises in wellness programmes and consults on executive and sexual health.
She says recent American research points to the mechanisms by which a good sex life can ward off illness.
The exact physiology is not clear, but one theory is that the intimate contact alerts the immune system and triggers a heightened "immune state".
The level of natural killer cells and antibodies that fight infection is at least one-third higher in couples who make love regularly, says Friedland.
"Regular lovemakers are thus likely to experience fewer colds, viruses and flu," she says.
Lovemaking is also a great stress-buster, because the stress-hormone, cortisol, is suppressed during sexual arousal. Some research shows that stressful negative thoughts and feelings of guilt disappear - at least for the duration of lovemaking.
As well, sex releases feel-good factors such as endorphins that are shown to lift depression, blunt anxiety and leave participants with a deep sense of wellbeing, she says.
Sex is not only good for the immune system, it can be good for fitness levels and Friedland makes the point that "every part of the body plays some role in the sexual act".
Some experts say that while sex is good for athletes if it is too vigorous, players will expend all the energy of their different body parts, and leave nothing for on the field the next day.
Ronaldo has some advice for that: He says players should simply "let the woman do most of the work". That way the lovemaking will be relaxing and conserve energy.
In relation to sports, sex shouldn't become compartmentalised and relegated to occasional bedroom interaction to prepare for important matches.
Sexuality is an energy that needs to be nurtured, a magnificent force that needs to be honoured and expressed healthily, says Friedland.
"It possesses both a body and a soul; a physical and a spiritual dimension. When this spiritual dimension is absent, sex can become an irrational and destructive force," she says.
Friedland quotes Dr Dean Ornish, Professor of Medicine at the University of California and author of Love and Survival, who says he is aware of no other factor with as great an impact on quality of life and incidence of illness than the healing power of love and intimacy.
The reality in a healthy monogamous relationship is quite different from the media hype, says Friedland.
Effort is required to nurture our sexual energy. It demands communication, relationship building, personal growth and a willingness to express our vulnerability, she says.
Of course, sex is as useful to prepare for individual sports as it is for big team games, says Gauteng athlete Glenn Macnamara.
Macnamara is a national duathlete (running and cycling) and was 16th in the world Power Man rankings at the beginning of this year.
He tells the story of a close friend, a Comrades runner, who had sex with his girlfriend till two in the morning, slept for two hours, then rose at four to get ready to run the famous ultra-marathon race.
"He ran his best Comrades time ever," says Macnamara.
There are others who disagree, and who believe that sportsmen, particularly rugby players, should abstain from sex before important games, to keep levels of the male sex hormone, testosterone, high.
"I don't believe that is necessary or effective," Macnamara says.
He prefers his wife, Niki, to accompany him when he competes internationally, whenever possible. He says the physical intimacy makes him "more relaxed and focused".
He is supported by top European cyclists, especially Italians, who believe sex is helpful to boost athletes' performance on the day.
According to physician Dr Linda Friedland, research shows that:
- A few minutes of lovemaking is equivalent to sprinting 220m.
It is demanding on the body, raising blood pressure, pulse and breathing rate.
- Starting from the top of the head, sexual arousal sparks off the release of neuro-transmitters (chemical messengers) in the brain which begin to stimulate the pituitary gland.
This is the "command centre" for lovemaking, that triggers a "cascade of hormones" to regulate sexual activity.
- The pituitary also sends messages to the adrenal gland which starts to produce sex hormones and within seconds releases adrenalin that increases the heart rate, blood pressure and rapid breathing.
- The genital areas become suffused with blood during lovemaking, to prepare them for the activity. Blood pressure can increase quite dramatically, because the heart is pumping so much faster. The "quick gasps" typical of lovemaking indicate the level of exertion taking place in the lungs, trying to get rid of the excess carbon dioxide.
- Muscle tension increases through the body during sex, and the skin's electrical resistance increases to heighten sensitivity particularly in the erogenous zones.
- Gastric acid secretion is also increased during lovemaking, possibly as a side effect of the adrenalin surge. This explains an increase in appetite after sex.
- After orgasm - as happens after a sprint - muscle tension relaxes immediately. The heartbeat returns to normal and the pituitary switches off the cascade of hormones.