Miami Heat forward LeBron James answers a question during a news conference on Friday, June 6, 2014, in San Antonio. The team plays Game 2 of the NBA Finals against the San Antonio Spurs on Sunday. (AP Photo/Tony Gutierrez)

When it's game one of the NBA Finals and you have the best basketball player on the planet, one you're paying $19 millon to keep that trophy in Miami, Job One would seem pretty obvious:

Keep LeBron James on the court.

Alas, human physiology doesn't always cooperate, and King James cramped up in the 90-degree heat of San Antonio's AT&T Center Thursday night while everyone from 38-year-old Tim Duncan to 22-year-old Kawhi Leonard survived. James also cramped up earlier in the playoffs against the Brooklyn Nets when no one else seemed similarly affected, and has a history of cramping.

So is James more prone to muscle cramps than most people? And if so why?

"We see this all the time," said Glenn Hardesty, an emergency medicine physician at Texas Health Arlington Memorial Hospital. "In any medical condition, why does it get expressed in one person and not another?"

Earlier Friday, my colleague Marissa Payne did an excellent job of explaining the complex mix of water and electrolytes that go into creating most muscle cramps. Lose too much volume or too much sodium, chloride, potassium and magnesium, and even elite athletes will cramp. (I think in LeBron's case we can rule out muscles that were under-trained for the task, a common affliction of newbie marathoners and weekend warriors everywhere.)

But that can't be the whole story, because LeBron took IV fluids, presumably with salt and other electrolytes, during the game, and again, no one else on the court appeared to cramp.

So let's look at some other factors. For one thing, people lose water and salt at very different rates. "Certainly some people are what we call 'salty sweaters'," said Pamela Nisevich Bede, a sports dietitian with the Swim, Bike, Run, Eat consulting group. "We'll finish a workout and we'll just be bathed in" salt.

And most people vastly underestimate their fluid loss. One study showed that people allowed to consume as much of a sports drink as they wanted every two miles during an extended run replaced, on average, only 30 percent of their sweat loss. In questionnaires after the run, they quite accurately gauged their fluid intake but were way off on their fluid loss.

Acclimation could be a major issue. Runners who train in mild climates for events in hot locations are warned to arrive at their destinations days ahead of time if they want to maximize performance. It takes the human body time to adjust to a change of temperature, and people do that at different rates as well.

Or maybe James just wasn't as prepared for the air conditioning to go out as other players were. "LeBron may start his day pretty well hydrated, but if you're not anticipating that kind of condition, you just might not be pushing the sodium the way you would if you were expecting" extreme heat, Bede said.

Or LeBron could be a victim of his own phenomenal skills. "As a starter, was more demand placed on him than, perhaps, on other players?" Hardesty asked. "Was he in the game longer? Is he faster?"

Unless LeBron's problem turns out to be an actual muscle injury, "I think he was likely exerting more energy and...on the court longer and perhaps...practicing harder," he said.

Then there's the delicious possibility that Powerade, which James endorses, wasn't up to the task of keeping him from cramping up. (Sports drink rival Gatorade didn't miss the chance to point this out, but apologized for its snarky tweets on Friday.)

But when compared the two beverages, they contained very similar amounts of electrolytes. "Gatorade contains 160 milligrams of sodium and 45 milligrams of potassium per serving, while Powerade contains 150 milligrams of sodium and 35 milligrams of potassium per serving. By comparison, Gatorade is slightly superior at replacing lost electrolytes," Livestrong concluded.

In the end, this just may be one of those mysteries no one can clear up, though it probably would be good for the Miami Heat trainers to figure it out if they want to keep their jobs.

"We understand why it happens, but our predictive analytics around who it's going to affect and who it's not are difficult to quantify," Hardesty said. "Some people are just more prone to depletion than others."