Piddock contain luminous chemicals
Britain's sailing squad has an extra weapon going into the Olympics - an extract from a sea creature which could help keep them ready to race.
They have been using a blood test using luminous chemicals taken from the common piddock, a marine mollusc.
Its developers, a husband and wife team of scientists based in Plymouth, claim it can detect the earliest signs of infection, or even overtraining.
This could allow treatment to be started, or extra rest taken, they say.
The piddock is a clam-like creature that burrows into rocks around the British shoreline.
It contains a protein called pholasin, which gives off light when it comes into contact with "free radical" chemicals.
High concentrations of these are normally released by white blood cells as a counter-measure against infection, and as such, they can be present even if no symptoms have yet been felt.
The test uses a pinprick of blood, which is mixed with pholasin in a test tube, and the resulting light levels emitted measured.
Dr Jan Knight, who has been working on the chemical with husband Robert for the last two decades, said that she was "excited" by the thought of it helping British Olympians.
She said: "What it allows them to do is, if an athlete is feeling tired, to carry out a test which can reveal if an infection is likely to be present.
"This could allow antibiotics to be started earlier than normal, if that is appropriate."
She said that full clinical trials of the technology were planned, and said that the test could even reveal, with some confidence, athletes with abnormal white blood cell activity due to overtraining.
She said: "We are becoming more and more confident in the accuracy of the results."
Knight Scientific, their company, also produces tests which can reveal the antioxidant levels in other substances, such as foods.
It owns two "farms" where piddocks are bred for the extraction of the chemical.
Professor Benjamin Chain, from University College London, said he had not encountered the test before, but that it was a "reasonable" way to investigate free radical levels.
He said: "This would be a useful way to measure white blood cell activity.
"The cells, in response to infection, are releasing an 'oxidative blast' of free radicals which aim to kill everything in that area, including themselves."