Too much exercise could lead to bad decisions, according to a new study in the journal Current Biology.
The study had athletes overtrain for three out of nine weeks and then compared them to a control group that did a normal nine-week training program. The overworked athletes performed worse on a physical test and failed tests of temptation.
For example, they were more likely to say they wanted $10 now instead of $50 in six months.
Scientists behind the study say that could explain why some athletes make the decision to use performance enhancing drugs.
One warning when extrapolating the findings of the study: Scientists say the study was done on elite endurance athletes. They said it's interesting information that suggests dedicated athletes should focus of regular exercise, but it may not apply to the average Joe.