At age 90, Margaret Bergmann Lambert seems to defy aging: she stands erect and moves gracefully, she talks with vigor and lives with brio. She jokes about the long legs and size 11 feet that made her one of the best high jumpers of her time.  And she remembers with restrained anger the isolation she felt as a Jewish athlete denied basic rights in Hitler's Germany, and how, despite equaling a national record in the high jump a month before the 1936 Berlin Summer Games, she was excluded from the German Olympic team because she was a Jew.  Gretel Bergmann, as she was then known, had been used by the Nazis to dupe Avery Brundage, the American Olympic Committee chief, and the Amateur Athletic Union into believing that Jews would be on the German team.  ''I can still hear that voice calling from within,'' she says in ''Hitler's Pawn,'' a fascinating new HBO Sports documentary (July 14, 10 p.m.). ''Jump! Continue to jump. Show them what a Jew is capable of doing, of being. ''  In one of the most dramatic moments in the 60-minute documentary, Lambert sits in a chair in her home and reads aloud, in German, the letter from a Nazi sports official that informed her, ''Looking back on your recent performances, you could not possibly have expected to be chosen for the team.'' While she would be provided with a free standing-room ticket, her hotel and transportation expenses to Berlin ''cannot be supplied.''  ''Heil Hitler!'' the official signed off. Lambert looks at the stained sheet of paper with the typewritten rejection. She examines the front, then the back, as if looking for something that makes sense.  ''That's it,'' she says, emits a tiny chuckle, then reminds viewers that the day before that letter was addressed to her, the United States Olympic team boarded a ship and headed to Berlin, oblivious to the notion that the Germans would conduct an elaborate fraud and disinformation campaign to avoid an American Olympic boycott.  That was how they would get rid of her, she says. Not by breaking her legs, but by waiting until the last possible minute, when the Americans were on the Atlantic, to spurn her. But she was a Jew, and to the Nazis, she says, ''We were dirt.''  She was unspeakably angry, but anger made her leap higher. ''A hundred thousand spectators seeing a Jew win,'' she says, ''would've been heaven.''  Heaven, or at least a better life, came after she emigrated to New York in 1937, married Bruno, now 93, a former track athlete who became a doctor, and reared two sons in a house in Queens. She is a compelling, wounded, humorous, plain-spoken, unsentimental woman who has had 68 years to distill Germany's betrayal.  In response to a letter from the producers seeking her cooperation, she wrote back that despite her age ''my brain is functioning quite well,'' but that if they wanted to know all the facts, ''don't wait too long.''  George Roy, the co-producer, said: ''She's easy to like, but for one who has lived her life, you'd think she'd be more emotional. We wondered if her character was going to translate on screen, if people would be smitten by her. But then we just let her talk, and the film pulsates whenever she's on.''  And she evidently grasps what it means to join the HBO family.  '''The Sopranos,''' she said last week after a screening of the documentary before an auditorium filled mostly with her large, extended family. '''Six Feet Under.' 'Sex and the City.' Margaret Lambert. A winning combination.''  Like other HBO Sports documentaries, ''Hitler's Pawn'' is enriched with excellent archival footage, including film of Lambert winning the high jump at the 1934 British Track and Field Championships, photographs and riveting interviews, many of them with other Jewish athletes with whom Lambert trained.  ''Everybody who was there stood in awe of Gretel Bergmann,'' Kurt Altschul, one of the athletes, said of meeting her in Ettlingen, Germany, where the Jewish athletes gathered to train. Yogi Mayer added, ''She reminded me of Nefertiti.''  The producers, Erik Kesten and Roy, also make widespread use of silent re-creations -- actors portray Lambert as a young girl and athlete and play children in her home village, Laupheim, and other athletes. The actress playing Lambert is a ranked high jumper in Germany, Roy said.  Re-creations can be intrusive (more so if they have dialogue), but these are haunting -- almost hypnotic -- especially when deep focus shots tie the elderly Lambert in the foreground to the young Gretel high-jumping in the background.  What, one wonders, would Marty Glickman have thought of this film? In a way, this is his story, too, told by a German Jew. Glickman, a broadcaster who died in 2001, was on the United States team in Berlin, but he was told by his coaches before the final trial heat of the 4x100-meter relay that he and Sam Stoller, both Jews, were being replaced by Jesse Owens and Ralph Metcalfe, who had not practiced for the event. Glickman always believed that the coaches, perhaps through Brundage, were appeasing Hitler.  Glickman and Lambert would find honor in what they were not allowed to do.
Richard Sandomir TV Sports column discusses HBO documentary Hitler's Pawn, which tells story of German high jumper Gretel Bergmann, who was barred at last minute from 1936 Berlin Olympics because she was Jewish; photo (M)