Los Angeles Chargers said at Fortune’s Brainstorm Health conference on Wednesday his Whoop wristband has helped him train smarter.

By Jonathan Vanian
May 04, 2017

You may think that NFL players’ hearts beat the fastest during intense moments like when trying to score the game-winning touchdown. However, Los Angeles Chargers safety Darrell Stuckey discovered that his heart rate peaks right before kickoff.

Stuckey explained at Fortune’s Brainstorm Health conference in San Diego on Wednesday that a small, Internet-connected wristband created by fitness tech company Whoop has helped him learn things about his body and health that he never would have otherwise known. The wristband and its sensors measure things like an athlete’s heart rate during exercise and rest, body movements, and surrounding temperature.

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From that data, Whoop can calculate how long it takes for athletes to recover from physical stress, said Whoop CEO Will Ahmad.

Stuckey learned that his “heart rate peaked before the game” because of anxiety. However, his heart rate would stabilize during the game as his anticipatory anxiety declined.

It’s this physiological data that has helped Stuckey understand his body so he could train and play better. One of the “the craziest” things he learned is that if he had alcohol before bed, it would take much longer for his body to recover from physical strain.

“Recovery drops dramatically if you have a couple of drinks before bed,” he said.

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Ahmad added that some players have discovered with the wristband that drinking sessions could impact their bodies up to four days later.

“The behavior in lifestyle ultimately affects recovery,” Ahmad said.

This story was originally published on Fortune.com.