MEMPHIS — Denny McCarthy sweated out a four-under-par 66 Thursday at the FedEx St. Jude Championship, and, OK, that’s not unusual amid a heat index those rose to 104 degrees at TPC Southwind—a place laden with water hazards and further soddened by copious amounts of perspiration.

In McCarthy’s case, however, the round was cooler than he has experienced in previous years in this FedEx Cup playoff opener and not because of a score that put him among the leaders.

There is no detail too trivial or minute that professional golfers won’t address to reach optimum performance, and in McCarthy’s case, that entails undergoing a “sweat test.” No, that is not a test to measure how one handles pressure on a golf course. It’s literally a test of fluid output through the pores.

Thomas Edison said that “genius is one percent inspiration and 99 percent perspiration,” but in McCarthy’s case, his genius was in realizing that his 99 percent perspiration was potentially holding back that one percent inspiration.

“I worry more about the heat than the test of golf. I sweat a lot. I struggle in the heat,” said McCarthy, who came into the week 45th in the FedEx Cup standings and needs a solid finish to stay in the top 50 and advance to the BMW Championship in Colorado. “I have a hard time getting things dry. I felt like I was preparing for battle this week, really.”

McCarthy struggled last year, finishing T-66 and falling from 24th to 35th in the FedEx Cup standings, essentially leaving himself with an uphill climb into the top 30 to qualify for the season finale, the Tour Championship. He ended up falling short and blamed the hyperhidrosis—the technical term for excessive sweating. He said his experience last year “was brutal every day, and it was hard to focus on my golf.”

So last fall he got “professionally sweat tested,” and the 31-year-old Florida resident said that the exercise has helped him to better deal with the heat.

In addition to more hydration and a change in his dietary choices before he tees off, McCarthy increases his sodium intake significantly.

“Yeah, I wasn’t even close to being properly hydrated. I was drinking things thinking that that was enough last year, and it wasn’t nearly enough,” he explained. “I needed way more salt and way more salt earlier in the day, and at nighttime, too. I was doing things thinking it was the right thing, and it wasn’t. So just a little change there, and that seemed to help today. It seems like it’s going to be hot again tomorrow, so I made sure I was on top of it coming into this week.”

Ranked 40th in the world, McCarthy has endured a frustrating season, slowed by some unspecified nagging injuries. He has posted three top-10 finishes that included a playoff loss to Akshay Bhatia at the Valero Texas Open. Ironically, the heat bearing down on the 70-man field was helpful this time.

“I just haven’t really been able to play the golf that I’ve wanted to,” he said. “Tried to forget about it. The heat actually helps those things loosen up in this kind of weather, as bad as it is for my sweating and whatever. It helps loosen these things up. I had a really hard time in Scotland with the cooler weather, those two weeks, Scottish and British. I had a hard time hitting the ball how I wanted to. It just was really hard. I had a couple things just really biting at me. It feels nice to kind of hit some shots that I know I’m capable of hitting, and I played a nice round of golf today.”

The inspiration had a chance to kick in.