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SWEAT SCIENCE

The next frontier of sports data analysis: bioanalytics
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PLAYER EFFICIENCY RATINGS, win shares and true shooting percentages—the advanced analytics of today—may soon seem quaint to basketball quants. This season the NBA's developmental league is taking the scientific approach one step further by embracing bioanalytics. On courts around the G League (née D-League), you might see players wearing what appear to be bandages on their forearms. You may watch scientists collect the strips, remove the gauze with tweezers, then drop the pads into labeled plastic bags. Stick around after the game, and you could find someone weighing water bottles on a scale and recording each measurement.

With the league signing a new partnership with Gatorade—which put the G in G League—teams will now have access to the resources of the Gatorade Sports Science Institute, the company's research branch, and its team of dietitians and advisers. "We're just trying to expose these guys to every aspect of how they can get better," says Nate Reinking, 43, coach of the Canton (Ohio) Charge, the Cavaliers' G League affiliate.

Before making the switch to coaching in 2013, Reinking, a point guard for four years at Kent State, had spent more than a decade as a pro overseas, mostly in the U.K. He also played for Great Britain at the 2012 London Olympics, and while training with the national team, he was introduced to the kind of sports science the Charge will now undergo, including sweat testing.

To determine how much players perspire, they are weighed before and after each game or practice. "If we know the duration of the practice and we measure how much fluid they're taking in, we can get a measure of sweat rate per hour," says Kortney Dalrymple, a senior scientist at GSSI who will be traveling to games and workouts to test players this season. (If nature calls between weigh-ins, that fluid has to be collected and weighed too.)

So much for quantity; by analyzing the sample in the gauze pad, scientists can determine the quality of the sweat. Each specimen will be put through a sodium analyzer, which measures the salinity of the fluid. Sodium is the main mineral lost in sweat—along with potassium, calcium and magnesium—and thus the most important electrolyte athletes need to replenish.

Knowing both fluid losses and sweat salinity allows sports scientists and dietitians to prescribe personalized hydration-strategy reports—what each player needs to drink during workouts and games, and how much. "To maintain performance," says each report, "you should lose no more than 2% of your bodyweight and avoid over-drinking."

Damien Wilkins, a nine-year NBA swingman, went through a comprehensive sweat test at the GSSI laboratory in Bradenton, Fla., last season, while on the roster of the Greensboro Swarm, the Hornets' affiliate. He used his results to better understand his body, and after four years without an NBA contract, Wilkins, 37, signed a one-year, $2.1 million deal with the Pacers in August. Says Wilkins, "I've made a lot of sacrifices through my career ... in order to have this opportunity again. I'm just so grateful for it."