The health and economic benefits claimed by cities hosting the Olympics or other major sporting events are unproven, researchers said on Friday.
Many host authorities justify the spiralling cost of staging a Games by pointing to legacy benefits including increased sporting activity, national pride and economic prosperity such as better housing and improved employment skills.
The organisers of London's 2012 Olympics used these arguments to justify its 9.3 billion pound ($13.34 billion) budget.
But a review of 54 studies written between 1978 and 2008 found "there is insufficient evidence to show that major multi-sport events like the Olympics benefit or harm the health and economy of the host population".
The researchers, who published their findings in the British Medical Journal, went on to say that future events could not be expected to automatically provide benefits.
"Until decision makers include robust, long-term evaluations as part of their design and implementation of events, it is unclear how the costs can be justified in terms of host population benefits," said lead author Gerry McCartney.
Sports participation can increase, as it did around Barcelona's hosting of the 1992 Olympics.
But it fell two percent after Manchester staged the 2002 Commonwealth Games, the research found, and it was mainly elite athletes who benefited from the new sports facilities.
The quality of the majority of studies were poor and at risk of bias, but the more reliable data showed the perceived economic benefits were often misguided, with some accounts indicating negative growth.
Inflation increased ahead of the Games in Barcelona, Atlanta 1996 and Sydney 2000, while health and education capital investment was neglected in Sydney in favour of sports infrastructure, some reports found.
The 1988 Calgary Winter Olympics and Manchester were deemed to have benefited, and there was more stock market activity in Sydney on the back of long-term business networking and improved market access.
House prices rose in Barcelona, Atlanta, Sydney and Athens compared with other areas of the host country.
Tourism showed mixed results with some cities enjoying a lift during Games time while others experienced a fall.
A British government spokesman said it would do all it could to get more people involved in sport, and added that UK-based companies had been awarded 5 billion pounds of direct contracts.
"Seventy-five pence in every pound on the Games is going towards the regeneration of East London and it is estimated that tourism will benefit nationally to the tune of 2 billion pounds," he said.
(Editing by Tim Castle and John Mehaffey;; To query or comment on this story email firstname.lastname@example.org)