PITTSBURGH (AP) _ An entertainer who says she created the idea of exercising to polka music is suing in federal court to have a businessman change his tune and quit using the name PolkAerobics.

Elena Goriscak of North Caldwell, N.J., charged trademark infringement and deceptive trade practices against Andy LoRusso in a civil suit originally filed in New Jersey and transferred to U.S. District Court here March 25.

''He's capitalizing on all the hard work I've done. This was my idea,'' said Mrs. Goriscak, who says she came up with the concept in 1983 and registered the name Polkarobics as a U.S. trademark on Sept. 3, 1985.

In her suit, Mrs. Goriscak said the competitor was ''so similar to my name that it will be virtually impossible for consumers of records, cassettes and entertainment performances to distinguish ... between Mr. LoRusso and myself.''

She asked the court to order LoRusso to quit using the name, pay her all gains and profits from his sales, and pay punitive damages. She sells an album and casette of polka songs and an exercise routine set to the three-step music.

LoRusso, who has been teaching PolkAerobics classes for the past year, says he came up with the idea in 1981 and has a 1983 copyright on a cassette tape he has been selling.

''I can prove first usage. There's no way I will stop doing what I'm doing. I promoted this thing for a lot of years. We have a very strong feeling these people picked up on what we were doing,'' LoRusso said in a telephone interview.

The polka, a snappy folk dance first performed 150 years ago in villages of what is now Czechoslovakia, has become chic after decades of popularity at ethnic weddings and beer halls. The National Academy of the Recording Arts and Sciences presented a Grammy for the first time this year for best polka album.

Mrs. Goriscak, a nightclub entertainer, said audiences responded so well to the polka she decided to pursue it as an exercise routine. With her daughter, Lynne, she gets crowds to bounce, clap, stretch, stamp, twist and wiggle.

''When we did the polka, it was so infectious. We are exercise buffs, and it is an aerobic dance. It's a workout. It's good, wholesome music anybody can have fun with,'' said Mrs. Goriscak, a coal miner's daughter who was raised in Buck Run, Pa.

LoRusso, also a former nightclub entertainer who once had a workout show on a Los Angeles cable TV station, said his idea was an offshoot of other workouts set to music.

''People hop and sweat to the polka at weddings and beer halls. I figured why not package it as a way to get in shape,'' LoRusso said.