Anne Sullivan and Paula Newnham, Harvard's women's cross country aces, experienced the difficulties of competition at high altitudes Saturday while competing in the women's national cross country championships at Denver, Colorado.

Struggling with the Mile-High City's "thin" air as well as the nation's top 240 collegiate distance runners. Sullivan and Newnham battled to 47th and 59th places, respectively.

Defending champion lowa State captured its fourth consecutive team crown while host University of Colorado's Mary Decker took the individual honors. Ivy-rival Princeton finished 12th in the team standings while the University of Maryland, which tied Harvard last week at the Eastern championships, grabbed ninth.

Running High

"The altitude was my biggest concern going into the meet, coach Robert "Pappy" Hunt said yesterday. "The girls started well--both were among the top 40 at the one-mile mark--but the thin air took its toll during the second and third miles."

Neither Newnham or Sullivan could produce the finishing kick that has characterized their racing styles this season.

Hunt refused to be downcast over the results. "We had two girls in the top 25 percent of the best runners in the country. I'd say that's pretty good," he added.

The experience gained by running against top competition under less than ideal circumstances can only help the pair in future races, Hunt said.

Sullivan, Newnham, and teammate Johanna Forman all will compete in this weekend's National AAU cross country championships in Memphis, Tennessee.