LeBron James ' longevity is often attributed to his exceptional work ethic and his annual investment in his physical well-being. However, while that is correct, many overlook another aspect of LeBron's ability to play this well for so long — his genetics.
In the book LeBron Inc., Brian Windhorst wrote about James' first strength coach in high school, who told him that he'd never seen a teenager's body respond so well to lifting weights as LeBron's. He noted that the "Young King" added muscle so quickly that by the time he was drafted into the NBA, he was already big and strong enough not only to hold his own against grown men but to dominate them.
Adding weight and muscle is almost always the main issue that incoming NBA rookies work on when they start their NBA careers. It wasn't for James. According to accounts, he weighed in at 230 pounds as a junior at St. Mary-St. Vincent High School and then bulked up to 240 after starting weight training.
But adding 10 pounds of muscle mass from the end of his junior year to draft night isn't really spectacular. Remember that Michael Jordan bulked up 15 pounds over the 1990 offseason to get ready for the Detroit Pistons . However, Windy said that while James was in Miami , he added seven pounds during a playoff game, which left even himself dumbfounded.
"This seems impossible and even LeBron can't explain it, other than to say he ate some protein bars at halftime and drank a lot of water," wrote Windhorst.
People often discuss the alleged $1 to $1.5 million that James spends annually to maintain his body and keep it in optimal shape. However, during an episode of the "Run it Back" show on FanDuel TV last March, three-time Sixth Man of the Year winner Lou Williams said that no matter how much money you spend on staying healthy, you're not going to get the results if you aren't genetically gifted.
"Everybody doesn't have the genetics to do that," said Lou Will. "I don't care how much money you throw at it. Listen, 60 percent of these guys can put $1 million into their bodies if they want to, they still ain't going to get these results. It's a credit to his genetics and how he's been able to maintain himself over the years."
Per the Cleveland Clinic , it takes four to 12 weeks to see the first physical improvement in muscle growth. However, factors such as how often one exercises, how much weight is being lifted, strength training, food intake, protein intake, rest and recovery, and most importantly, genetics can alter the numbers.
For mere mortals like you and me, muscle loss is inevitable as we grow older, and it's harder to add muscle mass at an advanced age. However, LeBron at 40 looks better than most of us ever.
He was still an All-NBA second team selection last season, his 22nd year in the league. And so if there is no dramatic drop off in his performance when he returns very soon, it won't be a surprise, and there is no secret juice to it. It's just hard work and God-given genetics.
This story was originally reported by Basketball Network on Nov 14, 2025, where it first appeared in the Off The Court section. Add Basketball Network as a Preferred Source by clicking here.
