Broken bones. Torn ligaments. Subpar performances.
They all combined to sideline some of the NFL's biggest stars a year ago, a lost season for several players who spent most of the year in the trainers' room.
Rob Gronkowski, Percy Harvin, Julio Jones, Robert Griffin III and Sam Bradford know all about that. So do guys such as Arian Foster, Doug Martin, Jeremy Maclin, Reggie Wayne, Malcom Floyd, Brian Cushing and Geno Atkins.
"I was rehabbing every day and it was miserable," said Gronkowski, the New England tight end who is still working his way back from a vicious two-year stretch in which he has had four forearm surgeries, a back injury and torn knee ligaments.
"Hopefully that never happens again," Gronkowski added. "And I don't wish anything on anyone like I had these past few years."
Harvin got a jumpstart on his comeback in February on the NFL's biggest stage. After missing most of the regular season and the playoffs with a surgically repaired hip and then a concussion, Harvin returned the opening kickoff of the second half of the Super Bowl for a touchdown in helping Seattle beat Denver.
"I don't know if any football player can say they're fully healthy playing football, but this is the best I've felt in a long, long time," Harvin said as the Seahawks opened training camp.
Philadelphia's Maclin tore a knee ligament in training camp last year and missed the entire season. But after an extensive rehabilitation process, the Eagles are counting on their speedy wide receiver to make big plays again.
"He was out there every day in the offseason program and it's just a matter of him getting his timing back," Eagles coach Chip Kelly said.
Wayne was off to a terrific start last year with 38 catches for 503 yards in seven games for Indianapolis. A torn ACL kept him out the last half of the season. Even at 35, he says he is ready to rebound.
Jones also was on his way to another Pro Bowl season with 41 catches in five games for the Falcons, but a broken right foot sent him to the sideline. He had a special cleat designed for him by Under Armour, a wider shoe that features a steel shank at the bottom for added support.
"I feel explosive, I still feel fast," he said. "I still feel like I can beat one-on-one matchups."
San Diego's Floyd missed almost all of last season after spraining his neck after making a reception at Philadelphia last Sept. 15.
Foster, one of the NFL's top running backs when healthy, considered retirement after a back injury limited him to eight games for the Texans.
"People die on the football field," Foster told ESPN. "This is a really brutal sport. Going through an injury like that, being 27 years old, I'm young, still I'm at the prime of my career. Is it worth it to try to come back?"
Martin, one of the league's rising running backs, ran for 1,454 yards and 11 touchdowns for Tampa Bay as a rookie in 2012. Last year, he struggled early, injured his shoulder and his sophomore season was done after just six games.
Another of the NFL's top rookies two years ago wasn't quite the same last season. After tearing his ACL in Washington's playoff loss, Griffin struggled a year ago to be the electrifying playmaker he was in his first season. With the Redskins out of the playoff hunt, then-coach Mike Shanahan ended Griffin's season and plugged in Kirk Cousins for the final three games.
"For me, personally, obviously, not having to come off of a knee surgery is a big boost for me," Griffin said, "having an opportunity to work on my craft during the offseason."
Philadelphia's Mark Sanchez could have a shot, too, after missing all last season with the Jets because of a shoulder injury — but he's Nick Foles' backup.
Griffin and St. Louis' Sam Bradford, who tore an ACL last season, might be front-runners for the AP Comeback Player of the Year award. Since it began in 1998, 11 of the winners have been quarterbacks — including the last six.
The award usually goes to a player who has overcome an injury, but San Diego's Philip Rivers bucked that trend last year when he won it for bouncing back from a season in which he didn't play up to par. There are a few quarterbacks other than Griffin who could fit that description this year: Baltimore's Joe Flacco, the Giants' Eli Manning, Oakland's Matt Schaub and the Jets' Michael Vick — already a previous winner — if he overtakes Geno Smith for the job.
A few defensive players could be in the running, too. Cincinnati's Atkins (torn ACL) and Leon Hall (torn Achilles tendon), Houston's Cushing (broken leg, torn ligament) and Denver's Demarcus Ware (career-low six sacks) are all contenders.
Then, there's also Ware's new Broncos teammate Von Miller, who was suspended six games for a drug violation and then lost after nine games with a torn ACL that caused him to miss Denver's Super Bowl run.
"I feel like I've been ready mentally back when the Super Bowl was here," Miller said. "But the competitor in me is definitely ready to go."