To understand football, Nate Jackson says, you need to remember one inherent truth about the game: a human body was not made to absorb that kind of punishment.

"There's no safe way to get hit by a truck," Jackson puts it.

Jackson, author of the football memoir Slow Getting Up, spent six seasons playing tight end for the Denver Broncos. Recounting a lifetime of football-related injuries is nearly impossible, because, as he put it: "You're always kind of battling with something."

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To hurry players back from injury, a cocktail of pain pills and anti-inflammatory injections are typically dispensed. Hydrocodone, Vicodin, Percocet, Toradol, Celebrex, Vioxx (before it was recalled for increasing the long-term risk of heart attacks and strokes) and so on. The widespread use of highly potent prescription pain drugs, some argue, has allowed the NFL to become the multibillion-dollar industry that it is today, but at a price.