Nine people were killed in the tornadoes that swept through central Oklahoma during the weekend, the state's chief medical examiner said.
The victims included two children and seven adults, said Amy Elliott, a spokeswoman for the medical examiner's office.
More top news
Charities warn that sitting down too long can lead to health risks such as type 2 diabetes and cardiovascular disease.
The Labour leader will use a speech to set out the differences between his party and the Conservatives with particular emphasis on the NHS.
Kate will join Prince William on a tour of the Stephen Lawrence Centre before visiting a charity working with disadvantaged young people.