Carl Zimmer examines them:
Del Percio’s team has...measured brain waves of athletes and nonathletes in action. In one experiment the researchers observed pistol shooters as they fired 120 times. In another experiment Del Percio had fencers balance on one foot. In both cases the scientists arrived at the same surprising results: The athletes’ brains were quieter, which means they devoted less brain activity to these motor tasks than nonathletes did. The reason, Del Percio argues, is that the brains of athletes are more efficient, so they produce the desired result with the help of fewer neurons. Del Percio’s research suggests that the more efficient a brain, the better job it does in sports. The scientists also found that when the pistol shooters hit their target, their brains tended to be quieter than when they missed.
Vaughan Bell adds his two cents.