Miami Researchers Find Link Between Cardiovascular Fitness and Hearing Sensitivity

Recent advances in medicine and changes toward healthy lifestyles have challenged some long held assumptions about inevitable aging changes, including hearing loss. Hearing loss in old age has always been considered to be an expected corollary of aging.

Although significant hearing loss is present in approximately one out of every three Americans aged 65 years and older, researchers at Miami University have learned that hearing sensitivity can be maintained very well into old age if people avoid exposure to loud noises at work or home for long periods of time, wear ear protection when exposed to loud noises, don't take certain medications that are ototoxic to the ear, and maintain a healthy cardiovascular fitness level. The exception to these findings would be a hearing loss with a genetic component and a family history of hearing impairment.

Research at Miami and at several other laboratories in the U.S. has consistently reported a positive relation between the cardiovascular system and functional ability of the organs and tissues in the inner ear. Much of the explanation behind the protective effects of cardiovascular fitness lies in enhanced circulation of blood that is needed to supply the bones and muscles of the inner ear.

When blood flow is impeded, the nutrients, antioxidants, and protective heat shock proteins, among other helpful components, will not be available. Blood flow can be impeded by cholesterol build-up in the walls of the artery and by vasoconstriction that occurs with high blood pressure, smoking, stress, and some personality types.

Miami's research over the past decade on more than 1,000 subjects ages 8 to 88 years old has resulted in several conclusions. First, hearing loss occurs with age, but noticeable hearing loss does not appear until after age 50. Also, having low cardiovascular fitness at any age is associated with worse hearing sensitivity compared to those with medium or high level cardiovascular fitness. Finally, people older than 50 who have moderate or high cardiovascular fitness levels maintain their hearing sensitivity comparable to people in their 30s. Kathleen Hutchinson, Speech Pathology and Audiology, and Helaine Alessio, Kinesiology and Health, speculate that the association of hearing loss and cardiovascular fitness are related by the common mechanism of blood circulation.