After four years of anticipation and endless hours of training, soccer players from 32 countries are doing everything they can to play their best at the World Cup. Among their last-minute preparations in South Africa, the athletes are eating well and sleeping enough. They might also be abstaining from sex — or not… In other studies, sex has had no effect on strength, power or endurance, added Ian Shrier, a sports medicine expert at McGill University in Montreal. "Sex is mild exercise and does not fatigue the body," Shrier said. "Hormonal spikes are controversial. And even if they did occur, it wouldn't matter because they have to affect performance through physical or psychological mechanisms. We know there are no physical effects."