High-impact aerobics enthusiasts may be jolting their inner ears into episodes of vertigo and inviting hearing loss from loud workout music.

Dizziness, ringing in the ears and loss of balance were found among aerobics teachers and others who do the popular form of exercise frequently, Michael I. Weintraub of New York Medical College reported in a recent issue of the New England Journal of Medicine.

Five recent cases prompted Weintraub to question 37 high-impact aerobics instructors at two fitness clubs; results suggested a link between the exercising and shock to the ears that could be causing damage to the inner ear, he said.

Among the five cases that alerted Weintraub was a 29-year-old aerobics teacher who suffered vertigo, skewed balance that caused her to inadvertently veer to the right and hearing loss.

In another case, a 20-year-old aerobics enthusiast suffered vertigo and general dizziness after exercising. A 42-year-old instructor suffered reduced hearing in one ear. And a 35-year-old instructor reported a muffled sound in one ear and sense of imbalance that worsened after exercising.

"The hearing loss . . . was thought to be related to exposure to the loud music played during the exercise routine," Weintraub wrote.

The injuries came despite the use of specially cushioned shoes, said Weintraub who said that the possible dangers of high-impact aerobics, a more intense form of jumping and running in place, need more study.