It's long been known that testosterone levels fall throughout the day, so by your rec league kickoff, you're running low. According to a new study out of the U.K., there's a simple way to slow the testosterone fizzle: A short, intense bout of weight training or sprints in the morning.

Using a semi-pro rugby team as lab rats, researchers took saliva samples to measure testosterone levels and then split the players into three groups: One did nothing in the morning (control), one ran five-by-40-meter sprints (sprinters), and a third bench-pressed and squatted for three reps at max weight (lifters). In the afternoon the team returned, gave another saliva sample and then all did a performance test of a three-rep maximum of back squats and bench presses, a 40-meter sprint, and countermovement jump.

The lifters had the highest afternoon testosterone levels and shined in the afternoon performance test, lifting and sprinting better. The sprinters elevated their afternoon sprints, but didn't perform as well on the lifting. Their testosterone levels were higher than the control group, but not as high as the lifters. The control group brought up the rear in both testosterone and performance.

The short burst in the morning, of an appropriate movement, seem to "prime the body for the event later in the day," says Christian Cook, one of the study authors. And "morning weight lifting appears to be more effective than sprints." But the results come with caveats. "These were all fast, strong guys," he says. "The lower you go down the [fitness] chain the less likely there is going to be a positive effect."

To experience benefits, weekend warriors should scale back intensity on the morning routine, he says, and everyone should only double down on game day.