French prodigy Victor Wembanyama said Monday he has bulked up significantly as he prepares for the physically demanding rigors of his debut NBA season with the San Antonio Spurs.

The 19-year-old 7ft 3in phenomenon's relatively slender physique was queried by some before he was chosen by San Antonio with the top pick in the NBA draft in June.

But Wembanyama revealed on Monday that he has gained significant weight following his arrival in Texas as he prepares for his first season in the world's most unforgiving basketball league.

"I've gained 10 to 15 pounds," Wembanyama told reporters at the Spurs media day.

"I try not to do too much, too quick. My physical condition is way better than any time in my life. We're good."

Wembanyama's arrival in San Antonio has been greeted with frenzied excitement in the city, with many hoping the player billed as a generational talent can lead the club back to the summit of the NBA.

Wembanyama said that after a brief break to recharge following his selection by San Antonio, he was soon back at work.

"I did get away from pretty much everything for some time, for a couple of weeks. That restored me totally," Wembanyama said.

"I often like to think the best players are the ones that work the hardest but you also need to know how to rest the hardest, and I rested the hardest for a couple of weeks.

"But then I was back here in San Antonio. I've been working better than any other moment in my life.

"Harder, but also smarter. And I think the off season will make a difference, not just for the upcoming season.

"The work we've done is going to impact the next few years I think."