The researchers measured everything from symptoms to the weight of nasal secretions (discarded tissues were weighed in a plastic bag, and the weight of the tissue and bag subtracted) to determine who became infected.

CNN: Study: Can more sleep help fight off colds?

To make the weight, Mr Ellicock packed a sleeping bag, climbing rope, biology textbook, ankle weights and "random bits of clothing".

BBC: London Marathon: Ex-paratrooper beats backpack record

To make the weight, Mr Ellicock is packing a sleeping bag, climbing rope, biology textbook, ankle weights and "random bits of clothing".

BBC: London Marathon: Ex-paratrooper runs for record