(CNN) — Here’s a look at performance-enhancing drugs in sports.
The use of performance-enhancing drugs by professional athletes, or “doping,” has been acknowledged as a problem since at least the 1960s.
The issue has gained prominence in the last 10 years as a result of the Bay Area Laboratory Co-Operative (BALCO) investigation, tell-alls by former professional athletes, a 2007 report on drugs in professional baseball and a scandal involving Russia’s 2014 Olympic team.
About Performance-Enhancing Drugs:
There are several types of performance-enhancing drugs, including: anabolic steroids, stimulants, human growth hormone and diuretics.
Anabolic steroids are natural and synthetic substances that help build muscle mass, enabling athletes to train harder and recover quickly from strenuous workouts.
Tetrahydrogestrinone, also known as THG or the Clear, is a powerful steroid purportedly used by such high profile athletes as track star Marion Jones and baseball player Barry Bonds.
Stimulants, including amphetamines, impact the central nervous system, increasing alertness and decreasing appetite.
Human growth hormone (HGH) is available only by prescription and is administered by injection. Athletes take it for improved endurance and strength although there is no definitive proof that it boosts athletic performance.
Androstenedione is a supplement that was sold over-the-counter until the FDA took action in 2004. It is banned by the NFL, Olympics, NCAA and MLB. The supplement is an anabolic steroid precursor, meaning that the body converts it into testosterone.
1967 – The International Olympic Committee (IOC) establishes a Medical Commission in response to an increase in the usage of performance enhancing substances.
1981 – After American discus thrower Ben Plucknett tests positive for steroids, he is banned from participating in future events by the International Amateur Athletics Federation (IAAF) and he is stripped of his world record.
1987 – The National Football League (NFL) begins testing players for steroids.
1988 – Congress passes the Anti-Drug Abuse Act, which makes possession and distribution of anabolic steroids for non-medical purposes a crime.
1990 – Congress strengthens the 1988 law by classifying anabolic steroids as a controlled substance.
1999 – The World Anti-Doping Agency (WADA) is established.
2000 – The U.S. Anti-Doping Agency (USADA) is established.
2002 – Federal authorities launch an investigation into BALCO, a California lab that is suspected of selling performance enhancing drugs to elite athletes. (See BALCO Fast Facts for more details).
2003 – Major League Baseball begins testing players for steroids.
February 2005 – Retired baseball star Jose Canseco publishes an autobiography, “Juiced: Wild Times, Rampant ‘Roids, Smash Hits and How Baseball Got Big.” In the book, Canseco recounts his own steroid use and implicates other players.
March 2005 – Six former and current Major League Baseball players testify before the House Government Reform Committee about drugs in baseball. They include Mark McGwire, Sammy Sosa and Canseco.
March 2006 – MLB Commissioner Bud Selig announces an investigation of steroid use among pro baseball players. Former U.S. Sen. George Mitchell will lead the investigation.
August 22, 2006 – The USADA bans sprinter Justin Gatlin for eight years after he tests positive for banned substances a second time. Gatlin is also forced to forfeit his 100-meter world record.
May 2007 – 1996 Tour de France winner Bjarne Riis admits using performance-enhancing drugs to win his title. Race organizers tell him to return his yellow first-place jersey.
September 20, 2007 – Cyclist Floyd Landis is stripped of his 2006 Tour de France title and he is banned for two years after a positive test for synthetic testosterone.
December 13, 2007 – The Mitchell Report is released. MLB players named in the steroid report include Barry Bonds, Roger Clemens and Andy Pettitte.
February 2008 – Former New York Mets clubhouse employee Kirk Radomski is sentenced to five years probation after pleading guilty to distributing steroids.
February 2009 – Alex Rodriguez admits to using performance-enhancing drugs while playing for the Texas Rangers.
January 2010 – Mark McGwire admits to using steroids during his career.
February 2012 – Three-time Tour de France winner Alberto Contador is stripped of his 2010 title for doping.
June 2012 – The USADA confirms that it is opening proceedings against Lance Armstrong and five former teammates. Armstrong denies the charges. (For more details about Armstrong’s case, visit Lance Armstrong Fast Facts).
August 2012 – American cyclist Tyler Hamilton is stripped of his gold medal from the 2004 Olympics after he admits to doping.
January 2013 – MLB announces it will begin random testing for HGH.
July 2013 – Ryan Braun of the Milwaukee Brewers is suspended without pay for the rest of the 2013 season for violating the league’s drug policy.
August 2013 – MLB suspends Kansas City Royals player Miguel Tejada for 105 games for amphetamine use.
August 2014 – Anthony Bosch, the founder of a Miami anti-aging clinic, surrenders to the Drug Enforcement Administration. He later pleads guilty to a charge of distributing steroids to athletes. His sentence is four years in federal prison.
September 2014 – The NFL and NFL Players Association reach an agreement regarding the league’s performance-enhancing drug policy. The agreement calls for HGH testing and an overhaul of the drug program.
January 2015 – Kenya’s Rita Jeptoo, a three-time Boston Marathon champion, is banned from competition for two years for doping.
September 2015 – The DEA announces that 90 people have been arrested and 16 underground steroid labs have been shut down in a sweeping drug bust called Operation Cyber Juice.
November 9, 2015 – A WADA report details evidence of doping in Russian athletics and a “deeply rooted culture of cheating at all levels.” Russia is provisionally suspended as a member of the IAAF in response to the doping allegations.
March 2016 – At a press conference, tennis player Maria Sharapova admits to failing a drug test at the Australian Open. She is suspended for two years.
July 2016 – A WADA report alleges Russia ran a state-sponsored doping program during the 2014 Sochi Winter Olympics.
August 4, 2016 – The IOC announces that 271 athletes from the 389-member Russian Olympic team have been cleared to participate in the Games. The rest of the team – 118 athletes – are banned in the wake of the doping scandal.
August 7, 2016 – A swimmer from the Chinese Olympic team tests positive for a banned substance called hydrochlorothiazide, a blood pressure drug that doubles as a diuretic.
August 11, 2016 – John Anzrah, a sprint coach for the Kenyan Olympic team, is sent home after allegedly posing as an athlete to take a drug test. He is the second Kenyan running coach to face allegations that he tried to help athletes cheat on doping tests. Michael Rotich, the team’s track and field manager, reportedly tried to bribe undercover journalists posing as coaches, offering to pay them in exchange for advance warning about drug tests.