MANKATO, Minn. - Embracing the challenge has always been a part of Adrian Peterson's persona. Bring it on, the star running back has often said with a smile.
He set the NFL's single-game rushing record as a rookie for the Vikings. His swift recovery from reconstructive left knee surgery last season included 2,097 yards rushing and the league MVP award. No matter how rare the feat he's asked about, Peterson will usually insist it's possible.
There's another test he'd eagerly take, one for human growth hormone.
"I can't wait until they draw my blood," Peterson said Friday after the team's first workout.
The NFL and the players union have been working on an agreement for HGH testing procedures. Supplemental HGH is a banned substance that is difficult to detect. It's been used by athletes for what are believed to be a variety of benefits.
"To be honest with you, I've been hoping they did this a long time ago, you know, evening out the playing field and making guys be honest and truthful to themselves," said Peterson, who believes HGH use is common around the league.
"You've got guys out there trying to provide for their families. They're going to try to get that edge, get that advantage."
Raider back on field after near-fatal injury
NAPA, Calif. - Raiders rookie cornerback D.J. Hayden was out on the practice field Friday, taking part in individual drills and even covering receivers in a few 11-on-11 sessions.
Hayden is working his way back from a near-fatal injury that cut his college career short and offseason surgery that kept him out of most minicamps and organized team activities.
Hayden was rushed into surgery in November after colliding with a teammate during practice while playing in college at Houston. He had a tear of the inferior vena cava, the large vein that carries blood from the lower half of the body to the heart. Doctors had to cut through Hayden's sternum to save him. The injury is 95 percent fatal in the field, according to doctors, and is most commonly associated with high-speed motor vehicle accidents.
Hayden worked his way back to health and was cleared by doctors before the draft. The Raiders selected him 12th overall and expressed confidence that the injury would not limit his NFL career.
• An MRI found that Bengals All-Pro receiver A.J. Green has a bruised knee that will force him to miss several days of practice.
• The Chiefs agreed to terms with No. 1 overall pick Eric Fisher on Friday. Fisher is a big right tackle out of Central Michigan.
• Jarvis Jenkins is the eighth Redskins player to receive an NFL drugs-related suspension in 22 months, sanctioned for four games Friday for testing positive for a banned performance enhancing substance.
• Packers cornerback Casey Hayward, who led NFL rookies last season with six interceptions, may miss two weeks of training camp because of a hamstring injury.
Until the Broncos and Ravens meet in Denver to kick off the 2013 season