"If you make four or five sprints you'll know what is the difference in playing at altitude," Dunga told reporters after Brazil's 19-match unbeaten run ended at the Hernando Siles in La Paz, 3,600 metres above sea level. "It's not inhuman to play at altitude, provided you have a period of adaptation.
"If there is time to adapt, there's no problem in playing at altitude, but to play here is not easy,"
There was nothing at stake in the match as Brazil had already qualified for the 2010 finals in South Africa while Bolivia had been eliminated though Dunga, who did not pick Kaka and Luis Fabiano for the match, denied he had not taken Bolivia seriously.
"I lined up the players best adapted to the altitude and we also have an important match at home and we have to rest those players," he added of their final qualifying match against Venezuela on Wednesday.
Brazil, who lost a World Cup qualifier for the first time in La Paz in 1993, supported a 2007 FIFA ban on matches more than 2,750 metres above sea level because of the danger to visiting players' health and an unfair advantage to home sides.
FIFA lifted the ban temporarily in May 2008 following protests mainly from Andean nations and so more research could be carried out.
However, it looks set to recommend a period of acclimatisation of at least two weeks.
Bolivia has countered with medical studies of its own, one of which concluded that teams arriving just before kickoff and leaving right afterwards barely feel the effects.
Coach Erwin Sanchez said Sunday's result was consolation after some poor results.
"But it leaves you with a sour taste because we beat the best (teams) and lost to the national teams we shouldn't have lost to (in La Paz)."
Bolivia won their home matches against Brazil, Paraguay and Argentina but lost to Venezuela, Ecuador and Chile.
