The ending came quietly. On New Year's Day, after 13 seasons, Jim Kleinsasser played his final NFL game, spending the three last hours plowing into whatever defenders got in his way. The Vikings tight end never touched the ball. He simply did what he'd been conditioned to do over the 181 games of his career: Sacrifice his body for the good of the team. As part of that routine, before suiting up to be a battering ram, Kleinsasser took a pregame painkilling injection of the anti-inflammatory drug Toradol. He learned long ago that the ideal NFL survival strategy requires a macho mentality. Suppress the pain, stay available -- no matter what it takes. "It's like a badge of honor to play through your pain," he said. "You're seeking validation and respect from your teammates and coaches. So you fight through it. And no, it doesn't feel good. But it feels rewarding that your teammates look at you like, 'Hey, this is a guy we can count on.' " As national debate over football's safety intensifies, the unrelenting pressure that players feel to perform is drawing new scrutiny. And the extensive use of the medications they commonly take to fight through all the pain is raising new alarm. The National Football League Players Association is pressuring the league to make changes to the game and its culture. Too many players, the union contends, are drifting toward drug misuse and abuse to stay on the field. It also wants players to be better educated by team doctors and trainers on the potential consequences of the painkilling drugs they often receive in the locker room. "We cannot kid ourselves, though," said DeMaurice Smith, NFLPA executive director. "The structure of the NFL calendar, for years, has perpetuated the use of these painkillers. The system of practices and games has required players to use these medicines to perform." For many players, the pain often calls for pregame injections of Toradol, a legal non-steroidal, anti-inflammatory drug that is non-narcotic and non-addictive, yet has several potentially serious side effects. Narcotics, like Vicodin or Oxycodone, also are sometimes required. Ambien is occasionally prescribed to aid sleep and help take the edge off. And over-the-counter medicine such as Tylenol, Aleve and Advil are used regularly. Adolpho Birch, NFL senior vice president of law and labor policy, said the league has great confidence in the talent and ethics of the medical staffs of all 32 clubs, warning not to blame team doctors and trainers for addiction problems players may develop. "It's a fact that the team physicians that are utilized by NFL clubs are among the best in the world at what they do,'' Birch said. Players agree that their own stubborn persistence to stay on the field contributes to a culture of playing in pain that then leads to the need to medicate. Kleinsasser rewinds to the 2002 season and the tibial plateau fracture he suffered after taking a direct helmet-to-knee shot early in the year. That injury, which typically has a recovery time of up to three months, cost him only two games. He was 25 and in a contract year. So he returned in a blink and played through the pain for the season's final 12 weeks. He did so, he says, to retain job security; to feed his passion for the game while the opportunity still existed; to make sure he didn't let the team down. "You miss a practice or a game and you're going to hear it. 'Awwww, are you OK? You gonna make it, Barbie?' Part of that helps and forces guys to reconsider, OK, maybe this injury isn't as bad as I'm thinking. We get ourselves into a mindset of, 'Hey, I can get through this.'" Kleinsasser played in every Vikings game over his final seven seasons - 112 consecutive contests. And before nearly every one since 2007, he says, he enhanced his durability with pre-game Toradol shots. "Sometimes I think about it and it's ruthless," he said. "But for our generation, that's just the way we were brought into this." Rage and regret While active, most NFL players rarely question protocol. But many former players are speaking out now, expressing outrage over the pressure-packed environment that, they say, put their health in jeopardy. Former Pro Bowl receiver Joe Horn, whose 12-year career ended in 2007 and included stops in Kansas City, New Orleans and Atlanta, is convinced that he too often put his long-term wellbeing in danger. He alleges that team personnel who could have helped protect players -- trainers and doctors -- instead found the quickest and quietest ways to make players available. That culture, Horn believes, preys upon the biggest weakness that just about every NFL player will admit to: A willingness to do anything in order to play. "By any means necessary," Horn said. "That's what drives you. It's a fear for job security. It's the enjoyment of the spotlight. The hype. The money. It's all that mixed into one."

In 2010, a study by researchers in Washington University's School of Medicine in St. Louis interviewed 644 former NFL players who had retired between 1979 and 2006. The research found that 52 percent of those players had used prescription painkillers while playing. And 71 percent indicated they had misused the drugs. The NFL continues to assert its concern for player safety. League spokesman Greg Aiello said NFL policy is "that medical decisions always override competitive ones.'' Horn doesn't buy that. He's hoping to create change by suing the NFL. He has joined 11 other former players, including past Vikings Chris Walsh and Sean Berton, in a suit filed last December in U.S. District Court. The chief accusation: The NFL, with a priority on profit, has been designed predominantly to get players back on the field as fast as possible with little regard for their health. More than 2,100 former players have filed dozens of lawsuits against the NFL, alleging that the league hid information that linked football-related head trauma to permanent head injuries. Those suits were consolidated into one master complaint in late May. In response, the NFL has cited the numerous health programs it maintains for current and former players, and medical benefits for players once they leave football. "The NFL has long made safety a priority and continues to do so,'' the league said in a statement. All 12 plaintiffs in the suit involving Horn maintain they suffered concussions during their NFL careers that could have been prevented and treated with greater care. According to the litigation, Berton now suffers from anxiety, depression, short-term memory problems, severe migraines, sleeping problems, light-headedness and dizziness because of the injuries he incurred over two seasons with the Vikings and one with the Giants. Walsh, a Vikings receiver and special teams gunner from 1994 until 2002, has similar problems and contends in the suit he was rarely warned about the dangers of returning to action too quickly. That's something he did too often, he believes, at times given a boost with a game-day dose of Toradol. Horn said that during his career hordes of players were persuaded to use Toradol without sufficient warning of possible side effects, which according to medical authorities include kidney failure, liver damage and gastrointestinal bleeding. One of Toradol's greatest advantages and biggest risks is that it can quell pain all over the body, making it possible for players to suffer serious injury, including concussion, without feeling it immediately. Furthermore, Toradol use can increase the risk of brain bleeding if a head injury is incurred, according to medical experts. "The doctors weren't telling us that," Horn said. "They weren't going to tell us that. Because if they knew it could get us on the field, they'd administer it." The Saints declined to comment on Horn's allegations. Attempts to obtain responses from the Chiefs and Falcons were unsuccessful. And five or six hours after games, with Toradol still in players' systems, Horn said postgame painkillers were easy to obtain, often distributed by trainers and medical personnel of the teams he played for, with few warnings. "Vicodin," Horn said, "was like popcorn." Behind the curtain The curtain concealing pain in the NFL is not often drawn. But it is evident, players say, on the plane rides back home from road games, creating scenes that Kleinsasser says are "far from glamorous." Some players deal with postgame pain by stuffing ice bags up their suit pants and beneath their shirts and ties. Aisles can be congested with other players receiving IVs. Occasionally, the quiet on the flight will be interrupted by the agonizing scream of a player in a full-body cramp. "One second you look over and a guy is sound asleep," Vikings defensive end Brian Robison said. "The next second, he's jumping up and acting like he's been stabbed. It's bad.'' Current players acknowledge the increased sophistication of medicine-free treatment available to them from team medical staffs -- from therapeutic ultrasound and massage therapy to ice baths and pain-relieving creams like IcyHot. But with discomfort ever-present and often worsening week after week, year after year, it's no wonder many players seek extra medicinal assistance -- from anti-inflammatories to sleeping pills to Toradol injections to painkilling narcotics. "That's one of the reasons there can be problems with prescription drugs," Vikings punter Chris Kluwe said. "Guys get injured. Or it may just be the cumulative wear and tear on your body. And after a while that adds up. You have these consistent nagging injuries that won't go away. So sometimes maybe you just need something to sleep. Sometimes you need something to dull the ache just a little bit longer. It's unfortunate. But it's one of those things that is going to be a part of football for as long as it's played."

Tony Richardson, a former Vikings fullback and longtime member of the NFLPA's executive committee, has become more vocal with calls for change. His 17 pro seasons included stints with the Cowboys, Chiefs, Vikings and Jets. He admits recognizing painkiller dependency among teammates over the years, guys, he says, who "literally would take pills every single day just to get to practice." The longer Richardson stayed active on the executive committee, the more his conversations with player reps and other players, past and present, opened his eyes. "You start realizing a lot of guys are self-medicating," Richardson said. "And not only are guys doing it during the season, they're doing it out of the season as well. ... I've played with a handful of guys who I've watched hit rock bottom. They'll self-medicate with painkillers. Then it's a snowball effect. They're taking the medication. Then they're drinking alcohol. Depression sets in and then all of a sudden everything around you is falling apart." Your job or health? Linebacker Barry Gardner played 110 regular-season games for the Patriots, Eagles, Browns and Jets. He is now the director of client development for the Minneapolis-based agency the Institute for Athletes, where he helps players transition into the NFL, and later, into retirement. He admits taking his share of Naprosyn, Vicodin, Oxycodone and Toradol when needed, although he says he steered clear of painkiller addiction. Those experiences allow him to relate to the pressures inherent in the profession. His career ended during the 2006 preseason when he broke his leg playing for New England. Thirteen screws and a 12-inch metal plate were surgically inserted to stabilize his ankle, fibula and tibia. Two years earlier, while with Cleveland, Gardner suffered a torn rotator cuff and torn labrum in his shoulder yet insisted on playing. With the aid of painkillers when the soreness became excruciating, plus game-day injections of Toradol, he said he played the final eight games of 2004, a contract year, with those injuries. "If you get hurt badly enough on Sunday, come Tuesday they've got five people at your position working out," Gardner said. "You can see that. And they make sure you can see that. You're in there on the training table trying to get back on the field and here come five dudes through the training room to take your position." The logical next step? "You pop pills," he said. "Some guys take Toradol before games. Playing with pain is something everyone does." Now 35, Gardner knows nagging pain will forever be a part of his life. He has that steel rod in his leg. His shoulders and hips ache on a daily basis. His neck is constantly stiff. But by surviving, Gardner says he made enough money to help several family members and invest in his own retirement income. So his advice to athletes is more pragmatic than preachy. "My biggest advice to guys would be to be available on Sundays," he said. "I'm serious. The NFL is just that competitive, man. ... You've got really, really good football players on the street that can't get jobs. So if you're hurt and in the training room, you're opening the door for somebody else to take your job. "What you have to come to grips with is this: Is your health more important than your job?" 'All about pain' Birch, the NFL senior vice president, warns against blaming teams for the misuse of drugs by players, but acknowledges that finding new ways to protect players has to be a league priority. He admits that the general public appears to have "a broad mistrust of what's going on [between team medical staffs and players].'' "But if you really dive down and talk about the individual relationships between the doctors and the players on a particular team,'' he said, "generally there are few if any serious issues." Birch said the framework for protecting players from misuse of drugs is already in place, pointing to strict written policies that dictate how controlled substances are to be stored, dispensed and administered by teams. Those guidelines, the league says, are not available to the public but compliant with Drug Enforcement Administration rules. Throughout the year, teams are also required to file regular reports detailing the inventory flow of prescription drugs. That data is funneled to Dr. Lawrence Brown, an NFL medical adviser specializing in substance abuse. Brown reviews it and looks for troubling signs. In 2009, the Vikings received an award from the league honoring their adherence to the NFL's Prescription Drug Program. Unlike most teams, the Vikings do not store medications on site at their Winter Park training facility. Instead, according to head athletic trainer Eric Sugarman, all prescriptions must be called in to the pharmacy the team uses. And at that point, the pharmacy delivers the exact prescription to Winter Park where it is directly given to the player for whom it is intended. Kleinsasser said the Vikings locker room bears no resemblance to scenes from the raucous 1970's pro football movie "North Dallas 40,'' in which drug abuse was prevalent. "Those painkillers, the Vicodin and all that stuff, isn't just handed out for any old reason -- at least with the Vikings,'' he said.