SONY DSCProfessional sports, especially high impact sports like football, put a heavy toll on the human body which often requires constant medical attention by team doctors. Despite being injured, many football players continue to go out on the field and are able to perform with seemingly little discomfort. On Sunday, federal drug agents conducted surprise inspections of National Football League team medical staffs as part of an investigation into suspected prescription drug abuse in the league, The Washington Post reports.

The Drug Enforcement Agency (DEA) is conducting the investigation with cooperation from the Transportation Security Administration; the agency believes that NFL teams dispense drugs illegally to keep players on the field in violation of the Controlled Substances Act, according to the article. Agents conducted bag searches and questioned team doctors while on the road playing away games, multiple teams were inspected but the DEA would not specify which ones or where.

A San Francisco 49ers spokesman confirmed they were inspected by federal agents following their game against the New York Giants. “The San Francisco 49ers organization was asked to participate in a random inspection with representatives from the DEA Sunday night at MetLife Stadium,” said Bob Lange, team spokesman, in an e-mailed statement. “The 49ers medical staff complied and the team departed the stadium as scheduled.”

The DEA confirmed that the investigation comes in the wake of a class-action lawsuit filed in federal court by more than 1,300 retired NFL players. The suit alleges that NFL team medical staffs violate federal and state laws on a regular basis with powerful addictive narcotic opioids, the article notes.

“The DEA has a responsibility under the Controlled Substances Act to ensure that registrants who possess, prescribe and dispense controlled substances are following the law,” said Rusty Payne, a DEA spokesman. “Doctors and nurse practitioners are held to very high standards when handling and dispensing controlled substances.”