On April 21, 1980, Ruiz appeared to win the Boston Marathon's female category with a time of 2:31:56. Her time would have been the fastest female time in Boston Marathon history as well as the third-fastest female time ever recorded in any marathon. However, suspicions mounted about Ruiz almost from the beginning. Men's winner Bill Rodgers, who had just won his third straight Boston Marathon, noticed that Ruiz could not recall many things that most runners know by heart, such as intervals and splits. Other observers noticed that Ruiz was not panting or coated in sweat, and her thighs were less lean and muscular than would be expected for a world-class runner. She later released stress-test results showing her resting heart rate as 76. Most female marathoners have a resting heart rate in the 50s or lower.