RIO DE JANEIRO >> Late in 1983, months before they announced a boycott of the Los Angeles Olympics, sports officials of the Soviet Union sent detailed instructions to the head of the nation’s track and field team.

Oral steroid tablets were not enough, they said, to ensure dominance at the 1984 Summer Games. The team should also inject its top athletes with three other kinds of anabolic steroids.

Providing precise measurements and timetables for the doping regimens, the officials said they had a sufficient supply of the banned substances on hand at the Research Institute of Physical Culture and Sports in Moscow, a division of the government’s sports committee.

The potent drugs were critical to keeping up with the competition, they wrote in the instructions.

The document — obtained by The New York Times from a former chief medical doctor for Soviet track and field — was signed by Dr. Sergei Portugalov, a Soviet sports doctor who went on to capitalize on a growing interest in new methods of doping.

Now, more than 30 years later, Portugalov is a central figure in Russia’s current doping scandal. Last fall, the World Anti-Doping Agency named him as a key broker of performance-enhancing drugs in Russia.

Revelations of the recent schemes compelled the international governing body for track and field to bar Russia’s team, usually a fixture on the medals podium, from the Rio Games.

The 1983 document and the account of Dr. Grigory Vorobiev, the former chief medical doctor, who spent more than three decades with the Soviet track team, provide new evidence of how far back Russia’s state-sponsored doping stretches.

Vorobiev’s career in Russian sports medicine lasted through the 1990s. In deteriorating health, Vorobiev, now 86, left Moscow five years ago for Chicago, where his son and grandchildren live.

Over two days of interviews in an assisted-living complex there, Vorobiev recounted his career. He spoke at the encouragement of his son, who said he wanted his father’s life documented in light of the recent doping revelations.

Vorobiev was one of the Soviet Union’s first full-time sports doctors. He specialized in improving coordination, strength and flexibility among elite athletes, with expertise in foot injuries.

Speaking Russian that was translated by his son, he described a system in which winning at any cost without getting caught was paramount. As a member of the medical commission of track and field’s global governing body, he policed doping at international competitions while knowing that many of Russia’s top athletes were using banned substances.

Vorobiev said he was not sure whether the doping scheme detailed in the 1983 document was carried out. Regardless, the communication captures the results-oriented mentality of the nation’s sports committee.

Not everyone chose to use illicit substances, he said, defending Soviet sports as not uniformly tainted. But low doses of oral steroids were common among top track athletes, Vorobiev said.

The anti-doping movement was in its infancy at that time. Still, anabolic steroids had been banned by the International Olympic Committee, and testing for them debuted at the 1976 Games, making the regimen that Soviet officials proposed for Los Angeles unambiguously prohibited.

The 1983 letter — addressed to Vorobiev’s boss, the head of Soviet track and field — cited competition as a main motivation for adding injections to the “special pharmacological profiles” developed for national athletes after a meeting of the country’s sports committee on Nov. 24, 1983. (The letter was translated independently from the original Russian by The New York Times.)

“A range of data,” the letter said, “proves that the main opponents of Soviet athletes will use the aforementioned injection form of anabolic steroids at the upcoming Olympic Games.”

The letter — signed and archived by Portugalov, and bearing the signature of a colleague at the Institute for Physical Culture, Roshen D. Seyfulla — said top athletes with chances of winning medals were prime candidates for injections.

Drawn into the plot, according to the document, was the Soviet anti-doping lab, which the officials — mindful of Olympic drug-testing — had recruited to determine how long the steroids in question would linger in the system.

In May 1984, about five months after the document outlining a doping plan was circulated, the Soviet Union withdrew from the Los Angeles Games, citing the “anti-Olympian actions of the U.S. authorities and organizers of the Games” in a statement.

But the fixation on beating the competition by using banned substances did not end, Vorobiev said, and Portugalov’s profile continued to rise.

For decades, Portugalov was a little-known figure outside Russia. Inside the country, however, he was a “fairly authoritative and very knowledgeable” figure who was not shy about advertising access to the best performance-enhancing substances, according to Vorobiev.

Vorobiev said that his own philosophy on developing elite athletes was not aligned with that of Portugalov’s, and that he preserved the document over several decades because he considered it proof of how Portugalov was masterminding the Soviet sports-science program.

Portugalov came to global prominence in 2014 when two Russian whistle-blowers identified him as a linchpin distributor in Russia’s state-run doping scheme. In the wake of a damning report published by the World Anti-Doping Agency last fall, Portugalov was suspended from Russian track and field and from his post at Russia’s sports research institute.

Portugalov could not be reached directly by The New York Times. A spokesman for WADA said the Russian Ministry of Sport had told the agency that Portugalov no longer worked for the government.

Investigations into his work, meanwhile, are continuing; last month, the global governing body for swimming appointed a lawyer to look into claims that Portugalov provided drugs to Russian swimmers.

Dick Pound, former president of the anti-doping agency who led last year’s investigation, called the 1983 document an unsurprising indication of the long history of Russia’s doping program.

“It shows the foundation on which a lot of this has been built,” he said. “The system we encountered is not new. It’s a continuation of the Soviet days.”

© 2016 The New York Times Company