Stress can help women fight flu more effectively, according to researchers at Birmingham University.
A short exercise or mental activity session has been found to boost their immunity to the flu virus, causing their bodies to produce more anti-bodies to tackle the infection.
The study, the first of its kind on humans, showed women who rode an exercise bike or did mental arithmetic for 45 minutes immediately before being given a flu jab recorded higher levels of antibodies than those who sat and read magazines for the same time.
Antibodies are produced by the body and contained in the blood to combat disease. A higher increase in antibody levels indicates higher immunity.
The findings, published in the current issue of Brain, Behaviour and Immunity, revealed that while chronic stress can suppress the body's immune system, acute stress can enhance it.
Dr Kate Edwards, of the university's School of Sport and Exercise Sciences, said: "We're suggesting that the effect of stress could all be in the timing.
"What we think is that the acute stress is activating the immune system; it's preparing it for a challenge. "It's perfectly possible that this response could prime the body's immune system against other common ailments and infections as well, although we would like to try similar tests on a group of elderly people, who are most vulnerable to viruses and so on.
"Chronic, long-term stress over many months and years is very bad for the body's immune system, but something like exam stress or first date nerves can actually raise the antibodies to fight infection."
A team of 60 healthy male and female students were recruited for the study, each was randomly asked to take part in one of three activities. After completing the task, each person received a flu vaccination.
Their antibody levels were measured after four weeks, and again 20 weeks later. These readings revealed women in the physical and mental stress groups had more antibodies to the A/Panama flu strain than those in the controlled reading group.
However, no change was noted in the male subjects, with each activity having little or no effect on their immune system. The exact mechanism of the immunological boost remains unclear.
Dr Edwards added: "This preliminary study has thrown up some interesting results, and we now want to look into whether stress tasks of different natures, durations, and timings in a variety of populations, may also have an immunity-boosting affect.
"If further studies support our initial findings, we may be recommending that something as simple as walking to the hospital or clinic to get a vaccination might help boost their immunity."
To read a full version of the paper visit www.sciencedirect.com/science