The heat is expected to be a problem during this summer's tournament in North America.
The measures taken by FIFA are not consistent with current science, the researchers, who work in health, climate and sport, wrote in an open letter, according to the BBC.
During the World Cup, there will be three-minute fluid breaks in each half. There will also be climate-controlled benches for substitutes and managers.
The researchers suggest, among other things, that fluid breaks be extended to at least six minutes and that opportunities for players to cool down be improved.
FIFA declined to comment on the scientists' statements, but said the game schedule was designed with the climate in mind.
