Golden State Warriors star Stephen Curry uses an underwater treadmill as part of his conditioning routine, allowing him to maintain his fitness while reducing the physical stress on his body.

Curry’s trainer explained that exercising underwater helps the veteran guard complete additional workouts without placing the same pressure on his joints as traditional on-court training.

“By going underwater, it provides less pressure on the joints so we can continue to do some fitness, get him moving, do more than we would on court without the pounding that is required for an athlete who’s been going for 17 years. Typically, if we go rep by rep, every rep, he’ll likely have a higher heart rate or a similar peak, but the recovery window, it tends to become less of a recovery every rep. If his rest period is active, which it is, or if it’s challenging.”

The trainer also discussed how Curry’s heart rate changes throughout the workout, explaining that the exercise allows them to monitor his conditioning and recovery between repetitions.

“That recovery period, if you see a really good drop in heart rate, that shows an indication that he’s recovered or aerobic fitness. But if he’s passively resting or he has a longer rest period, that helps. But this is a 1 to 1 ratio. And he’s still running in between. So we’re likely going to get a similar spike, 150, 160, maybe 65 near the end. But his heart rate before he starts his next rep is probably going to be a little bit higher because he’s still trying to recover from the workload.”