Jamie will be running across Canada during part of their winter, so will encounter Arctic temperatures he has never experienced before.
We took him to Gloucerstershire University's Sport & Exercise Laboratory where they have a chamber in which the temperature can be lowered to minus 20C.
More top news
A couple who lost an unborn baby to complications from twin to twin transfusion syndrome have raised money for research into the condition.
Dorset has a new migrant population - barrel jellyfish are washing up in their dozens on its shores.
The family of one of Britain's oldest poppy-sellers say charities which bombarded her with donation requests were not to blame for her death