Marathon running places huge demands on the body
A team from Liverpool John Moores University have teamed up with Cancer Research UK to monitor the effects of the 26.2 mile race on a sample of amateur runners.
Thousands of ordinary people regularly run marathons raising millions of pounds for charities.
However, very little research has been done into the physiological impact of their exertions.
This year a number of volunteers running for Cancer Research UK have been keeping detailed records of their training programmes, sleep patterns, injuries and levels of fitness and motivation.
Heart tests
Dr Ben Edwards, of Liverpool John Moores University, said: "We will be looking at levels of success between the various ages and sexes of those taking part.
"For example do men or women take the training most seriously? Who paces themselves best on the day? And who is likely to be motivated enough to keep up all that good work after Sunday?"
Dr Edwards said the 200 runners taking part in the tests would be also be asked to keep a diary of their training habits after the big event to determine if they had slipped back into bad habits or whether marathon running had inspired a fitter lifestyle.
More detailed tests on a smaller sample of charity participants will examine physiological affects such the impact on the heart, and body temperature.
Dr Edwards added: "In last year's London Marathon a large percentage of people taking part were running for charity. We are looking at how their bodies cope.
"It is a massive holistic view looking at training, motivation, goals as well as the effects of running the race and what happens afterwards. We hope our findings will be ready for next year's marathon."
Up to 41,000 people are expected to line up for this year's Flora London Marathon which gets under way at 0900 BST