When tailback Clinton Portis sauntered off the field in helmet and pads after yesterday morning's practice, it was difficult to notice any difference in his physique from last season. In both practice sessions -- the other in the afternoon -- Portis exhibited his usual explosiveness and shiftiness.

But Portis said he has gained almost 20 pounds to help withstand the pounding of the regular season as the centerpiece of Coach Joe Gibbs's offense. Portis is listed on the Redskins's official roster at 5 feet 11 and 212 pounds, an increase of seven pounds from last season. But roster weights are fluid and not exact.

Portis claimed he weighs about 225 pounds after playing last season between 205 and 207, the heaviest in his career.

"I picked up 20 pounds getting in the weight room," Portis, 23, said, sweating after the morning practice. "I guess age [contributed]. I'm getting old."

The third-year veteran chuckled, then turned serious.

"Pretty much it was just working [out]. I knew what it was going to take. I knew I needed to pick up weight for the type of offense that we're running. In the two-yard gains, I probably need this weight to turn 'em into four or five."

Last season Portis amassed 1,315 rushing yards, the sixth-highest figure in franchise history. But the scatback-sized runner took a pounding while averaging only 3.8 yards, often running in between tackles like a power back.

"As the season wears on, some of the weight is going to disappear," said Portis, who gained an average of 5.5 yards per rush in his first two NFL seasons. "I think last year, early on, I was probably a little worn down. This year, I'm looking to be in it for the long run. It's going to be physical. There's going to be contact made. And I'm going to be the one making it."

The Redskins have altered their blocking schemes to better accommodate Portis, who prefers open space. But the counter trey -- which requires patience and pounding -- will remain a staple. Unlike other runners his size, Portis, who runs with power and finesse, gains much of his yards running up the middle.

Portis said he increased his girth without any prodding from Redskins coaches. Portis, who impressed his coaches with perfect attendance during the offseason, worked out religiously in the weight room at Redskins Park.

"I just felt like that's what I needed to do," said Portis, who played his first two seasons with the Broncos. "Out in Denver, I didn't need this weight. It was hit or miss. Here, it might be grinding; it might be hit-or-miss. You never know, but just in case it's another grinding period, I'll be prepared."

Several teammates said although Portis appears to be a tad more powerful in his runs, they didn't realize he gained so much weight.

"He looks a little bit bigger," said left guard Derrick Dockery, who is 6-6, 335 pounds.

" I don't know about 20 pounds of muscle. But you know him. He's going to say something that grabs attention.

"But I don't think it's impossible to gain that much. With hard dedication it can be done. If I had to guess, I'd day he gained about six pounds. But I can't doubt him because people say I look about 300 pounds. Who knows."

Arrington Dashes Toward Return

Linebacker LaVar Arrington took an important step toward returning to the field by easily passing a conditioning test, consisting of 14 40-yard dashes. Arrington, who is recovering from a knee injury that required two surgeries, appears likely to participate in limited practice starting next week.

"He passed it with flying colors," said Bubba Tyer, director of sports medicine. "We're real proud of him. He did great. We're getting close." . . .

Gibbs spent considerable time after the afternoon practice with about 25 soldiers who were being treated at the Walter Reed Hospital for injuries suffered in Iraq. . . .

Wide receiver Santana Moss missed the afternoon session with a stomach virus. Defensive end Phillip Daniels (sore wrist) also missed the afternoon session. Cornerback Shawn Springs was back at practice yesterday morning after missing Monday's session with a sore hamstring but skipped the afternoon workout as a precautionary measure.

Offensive lineman Ray Brown (knee) missed the afternoon session, but is expected to practice today.