LOS ANGELES -- They observe in jerseys, and for those who can, they participate in controlled spring conditioning drills, walk-throughs, and mental preparation. Some even walk the steep steps of the Coliseum from bottom to top and back down again.

But no matter what they do, USC's walking wounded aren’t remotely in the same condition as their healthy brethren, who are fit enough to stretch the limits of their physical being in Steve Sarkisian’s nonstop practice pace.

Sarkisian, USC's first-year head coach, is a great believer in muscle memory, which basically means one learns from doing rather than watching. In his incredibly fast paced, no-huddle offense and rotating defense, muscle memory must also go hand-in-hand with muscle conditioning.

Despite watching their teammates practice and condition at a pace not seen on Howard Jones/Brian Kennedy Fields, there is an uneasiness that come regular season camp, in the heat of summer, the currently rehabilitating players could be in for a major conditioning shock.

Sarkisian feels that his available players in spring ball are now rounding into the type of shape needed for the regular season, and spring ball has been a catalyst to being in the type of condition needed for fall competition.

“That’s why we practice the way that we do,” Sarkisian said. “That’s why we make it as hard we can throughout practice. This prepares our guys for a game-like atmosphere.”

Come practice in August, Sarkisian expects his healthy players to return ready to go from a conditioning standpoint, and he also knows the conditioning challenge is even more pronounced for those rehabbing.

“The guys [who] are injured have their work cut out for them when they get back,” Sarkisian said.

Here are six rehabilitating players being held out of spring ball (for the most part) who are expected to be key contributors in 2014. They all will be faced with the challenge of getting into “Sarkisian shape” by early August:

• RB Justin Davis: Given the sophomore’s early track record of success on and off the field, Davis -- who suffered a season-ending broken ankle in 2013 -- figures to be ready with an indisputable work ethic and relentless motor. Expect him to enter fall camp in top condition.

• LB Lamar Dawson: Recovering from a left knee injury, this senior will not only battle junior Anthony Sarao for his starting inside linebacker position, but he will have to be in the type of shape that Sarao knows all too well. Sarao has really come on and plays with a high motor and intelligence, so Dawson has his work cut out for him in more ways than one.

• WR Steven Mitchell: The redshirt freshman is an electrifying player when healthy. Recovering from tearing ligaments in his right knee during the summer of 2013, Mitchell says he is still on the mend but expects to be in ready to go in August. A hard worker, the former Bishop Alemany star’s return would be a major addition for the currently ultra-thin receiving corps.

• OG Jordan Simmons: With his size (6-foot-4, 335) and the pace of the offense, will the sophomore be able to come into camp in the type of shape needed for the no-huddle offense? Simmons, recovering from knee surgery, could very well be a key and the final piece of the offensive line. So far Simmons is still potential and an unproven talent.

• TE Randall Telfer: With Xavier Grimble leaving early for the NFL draft, it appeared that Telfer would step right in. The senior might still do so, but he has been held out of spring ball with a knee issue, and his absence has opened the way for an impressive March and April by junior Jalen Cope-Fitzpatrick. It would behoove Telfer to be in the best condition of his Trojans career to hold off Cope-Fitzpatrick and the incoming presence of true freshman talent Bryce Dixon.

• OG Aundrey Walker: There are those both within the team and onlookers who say that Walker, now a senior, has the talent. But does he have the motivation? The Ohio native has spent spring practice observing and going through “soft” drills, but one wonders how the 6-foot-6, 300-pound guard will cope with the physical and mental conditioning demands to play in Sarkisian’s never-take-a-breath offense.