Strike Two for Ben Johnson : Track and field: He is found guilty of breaking performance-enhancing substance rules again and could face lifetime ban.

For the second time in less than five years, Canadian sprinter Ben Johnson was found guilty Friday of violating track and field’s regulations against the use of performance-enhancing substances.

The high level of the male hormone testosterone in his system during a recent test was “clear cut” evidence, the International Amateur Athletic Federation said Friday after a meeting in Paris of its five-member doping commission.

Pending appeal, Johnson, 31, could be suspended for life for a second offense. He served a two-year suspension after testing positive for an anabolic steroid when he finished first in the 100 meters in the 1988 Summer Olympics at Seoul.

“The 1988 Olympic Games doping offense by this athlete was a tragic embarrassment to the world amateur sport movement and to Canada,” said Paul Dupre, president of Athletics Canada in a statement.

“This second doping offense by Ben Johnson, while tragic in human terms, is equally serious. Now, this former athlete, alone, must assume the burden of this latest embarrassment.”

Johnson, who within the last two months seemed to be on the verge of regaining the form that allowed him to set two world records in the 100 in 1987 and ‘88, was unavailable for comment Friday, but his lawyer denied any wrongdoing by the runner.

“Mr. Johnson stands by his earlier statement that he has taken no prohibited substances and has engaged in no improper practices,” Terrence O’Sullivan said.

The IAAF’s general secretary, Istvan Gyulai, said in a statement that an “excessive level” of testosterone was discovered in the urine sample that Johnson submitted during a test after an indoor meet Jan. 17 at Montreal.

Testing for the male hormone is controversial because it is naturally produced. But sports governing bodies, such as the IAAF, determined 10 years ago that it was necessary to develop a test for testosterone because athletes believed injecting extra dosages into their systems would improve their performances.

Although doctors contend that the normal ratio of testosterone to epitestosterone in the body is 1:1, sports governing bodies have trod carefully, declaring a test positive only if the ratio is higher than 6:1.

Since last year, they have ruled that cases in which the ratio is between 6:1 and 10:1 should be subject to further review, even though studies have shown that the odds of a person having a ratio of greater than 6:1 are one in 10,000.

According to the IAAF, Johnson’s test revealed a ratio of 10.3:1. Two earlier tests, one on Jan. 15, were negative, indicating to the IAAF that he took the substance within two days of the meet at Montreal.

“This is a clear-cut case of testosterone doping,” said the IAAF medical commission’s chairman, Dr. Arne Ljungqvist of Sweden.

Johnson is the second Canadian track and field athlete to test positive for testosterone this winter. Triple jumper Oral O’Gilvie was the first.

“I predicted in ’89 testosterone would be the drug of choice, and most likely it is,” said Edwin Moses, the former hurdler who served for four years as chairman of the U.S. Olympic Committee’s medical commission.

Critical of the trend toward leniency for athletes whose testosterone-epitestosterone ratio is higher than 6:1, he said, “If I had been an athlete who was going to use drugs, that would have been a green light.”

But the IAAF had little choice but to present Johnson with a red light.

“I’m not totally surprised,” his former sprint rival, Carl Lewis, told the Houston Post. “Ben was at the point in his career that he either had to run better or look for a job.

“I’m not going to . . . kick him while he’s down. What I will say is this: If he used drugs, I’m glad he got caught. I don’t think anything is that important in life.”