According to a Canadian study presented in 2010, running a marathon can temporarily result in decreased function of more than half the muscle segments in the heart's main pumping chamber, but neighboring segments are generally able to compensate. Full recovery is reached within three months. The fitter the runner, the less the effect. The runners with decreased left ventricle function had an average peak weekly training distance of , while those who did not averaged . The marathon was held in weather. According to one of the researchers: "Regular exercise reduces cardiovascular risk by a factor of two or three in the long run, but while we're doing vigorous exercise such as marathon running, our cardiac risk increases by seven."