"Pep pills"--as tested on 57 Harvard undergraduates--have a significant effect upon athletes, the American Medical Association reported yesterday. The study, under way for the past two years, showed that up to a four per cent improvement in athletic performance results from use of the drugs.

Although the testing did not involve any intercollegiate athletic contests, the undergraduates performed under conditions simulating these meets. Weight throwers, swimmers, and runners participated in the controlled experiment, and registered "improvement" following dosage.

The 57 athletes, given either the drug amphetamine or a placebo, were tested nearly 800 times. Drs. Gene M. Smith and Henry K. Beecher conducted the Harvard study, which was correlated with similar work done at Springfield College, and with a national survey of coaches.

"In all three classes of athletes," the researchers' report stated, "the majority of subjects performed better under amphetamine than under placebo." Over three-quarters of those receiving the drug did better than when performing with a placebo dose.

Following the publication of the survey, the A.M.A. strongly criticized the use of "pep pills" in any sort of contest. The nationwide poll showed, however, that only one per cent of coaches administer such drugs to their athletes.

Drs. Beecher and Smith checked swimming times, running speeds, shot-putting, and weight-throwing in their study. Weight-throwers registered the greatest improvement, with a three to four per cent increase in performance after dosage.