SAN DIEGO -- Ryan Mathews, the heir apparent to LaDainian Tomlinson, made it to training camp in time to take part in the San Diego Chargers' first practice in full pads.

"The adrenaline was rushing and I learned a lot of new stuff," Mathews said Sunday evening, hours after signing a five-year, $25.65 million contract, with just more than $15 million in guaranteed money. "Everyone is going 100 miles an hour -- safeties, linebackers coming at you a little harder in pads. It's football and I love to play it. It's all fun."

Mathews missed seven practices, including three for rookies and selected veterans last week.

"I've got a little bit of making up to do, but that will happen in the next couple of days," he said.

San Diego moved up 16 spots in the draft to take Mathews with the 12th pick overall. He'll replace Tomlinson, the 2006 NFL MVP who was released in the offseason and then signed with the New York Jets.

Mathews is San Diego's first new featured back since Tomlinson was a rookie in 2001. Tomlinson missed most of training camp that year during a holdout but ran for 113 yards and two touchdowns in the season opener.

"Myself, I'm just here to help the team win," Mathews said. "That is the No. 1 thing why they drafted me. That is all I can say. My role on the team is just to run the ball and help the team do what it can to get to the last game of the year."

General manager A.J. Smith didn't return calls seeking comment.

Mathews rushed for 3,280 yards in three seasons at Fresno State, scoring a school-record 39 touchdowns and averaging 6.1 yards per carry.

Last season as a junior he rushed for 100 yards against three Top 25 teams, Cincinnati, Boise State and Wisconsin. He ran for 234 yards against Boise State, scoring on runs of 69, 60 and 68 yards.

The Chargers still have three holdouts. Linebacker Shawne Merriman, left tackle Marcus McNeill and Pro Bowl wide receiver Vincent Jackson are unhappy about their status as restricted free agents.

McNeill and Jackson are expected to stay away through the first 10 games of the season, returning for the final six games in order to accrue a season toward unrestricted free agency. It's not known when Merriman will report.