There’s science behind why you make dumb decisions after the turn – but you can do something about it.

A study by the french Institute of Health and Research explored how cognitive thinking is impacted when your brain has been sufficiently taxed. Its testing revealed that an overworked brain is no different than cramping leg muscles in the final kilometres of a marathon – the simplest tasks become arduous. “The cerebral gears start slipping and impulsiveness kicks in,” a summary of the study said.

If you play a lot of golf, this should come as no surprise. Floundering on the back nine is a tale often told over beers at the 19th hole. It happens to the pros, too. Rory McIlroy’s putting mishaps on Sunday at the US Open could be chalked up to brain fog. Prior to the first of two misses inside four feet in the closing holes, he had made 496 consecutive putts from three feet and closer.

Also, don’t forget that Phil Mickelson double-bogeyed the 18th hole to lose the 2006 US Open and Jordan Spieth put two shots in the water on the 12th hole to surrender a commanding lead in the 2016 Masters.

Coincidences? Maybe. But their personalties and the situations at hand seem to support the study’s findings. McIlroy, Mickelson and Spieth are three of the more cerebral pro golfers and each was faced with a complex assortment of challenges. McIlroy was closing in on his first major title in nearly a decade. Mickelson had meticulously analysed every hole at Winged Foot in search of his first US Open. And Spieth was trying to extend a streak of seven consecutive rounds with the lead at Augusta while also clearly fighting his swing.

So what can you do to avoid crashing like them on the back nine? Here are five helpful tips.

1. Your conditioning matters
The better your fitness, the less likely fatigue will cloud your decisions. “Give yourself a chance to not be as gassed as early as you would be,” says Selena Samuela, a Peloton instructor and golf-fitness trainer. “If you’re tired by the 12th hole, you’re in a battle with yourself.”    

2. Build in breaks
A stressful round doesn’t need to be stressful the whole time, says Matt Cuccaro, a golf performance coach: “Whether it’s being social or enjoying the environment, anything that takes you out of the task and be lighter is going to help you stay fresh.”

3. Rely on sound fundamentals 
Stress compromises your swing. Golf Digest Teaching Professional Michael Breed says understanding the basics of your setup (posture, grip, alignment) gives you something to rely on when things get foggy.

4. Conserve brain power 
Don’t get bogged down by stuff that is out of your hands, Cuccaro says. For example, focus on where you want the ball to start, not finish. “The finish is largely out of our control,” he says.

5. Be your own caddie
Just knowing your decision-making isn’t great at the end of a round allows you to prepare, Cuccaro says. If you were your caddie, what would you be telling yourself in these fatiguing moments to avoid a meltdown? 

Photo: kevin c. cox/getty images