On Wednesday night, LeBron James and the Cleveland Cavaliers suffered a frustrating loss to the Denver Nuggets. After the defending NBA champions lost 126-113, a sense of defeat reportedly dominated the locker room, where James had some choice words on the role of toughness in an athletic contest.

“You can’t preach toughness. You’ve got to have it,” James told the reporters gathered in the locker room. His comment suggests that the team’s loss was due to some inherent failure of individual team members: He implied that toughness is something that must come from within and can’t be taught.

But research on the subject suggests that King James may be wrong.

Can toughness be learned? Lebron doesn't think so, but scientists disagree.

A study published in February in the International Journal of Exercise Science suggests that James is off-base. Researchers at Baylor University interviewed NCAA strength and conditioning coaches on their experiences with players’ mental toughness and found not only that most of them believe that mental toughness is not only important to athletic importance but also that the majority of them believe that mental toughness can be developed.

Another study, published in January in the International Journal of Exercise Science, also refutes James’s belief that athletes simply must possess toughness. The paper’s authors studied college athletes who participated in a variety of sports to find out whether specializing in a sport early in life had an influence on an athlete’s mental toughness. While they didn’t find a relationship between specialization and toughness, they did assert that toughness can be developed through experience. “Mental toughness develops over the years by maximizing athletes’ opportunities and competition experiences, and athletes can develop their mental toughness by choosing to specialize or diversify in sports,” the study’s authors wrote.

While James may be wrong about whether you can preach toughness, he’s right about one thing: Toughness matters in sports.

A 2004 study of top-level rugby players in the journal Personality and Individual Differences found that athletes playing at the highest level of the sport all scored significantly higher than other players on measures of mental toughness.

So yes, LeBron James has one thing right about toughness in an athletic contest: “You’ve got to have it.” But fortunately for the rest of the Cavs, you can, in fact, develop it.

Photos via Getty Images / Harry How, Getty Images / Gregory Shamus