Cardiology.

The Exercise Paradox

The risk of sudden death is 14-45 times greater during vigorous exertion than during rest or light exertion, but paradoxically that risk is blunted in people who exercise regularly, reported Dr. Christine M. Albert of Brigham and Women's Hospital, Boston, and her associates.

They analyzed data from the Physicians' Health Study and found that there were 122 sudden deaths among the 21,481 study subjects during 12 years of follow-up. Approximately 19% of the deaths occurred during or within 30 minutes of completing activities such as jogging, sports, and heavy yard work or home repairs.

In men who rarely engaged in vigorous activity, the relative risk of such death was 74, compared with a relative risk of 11 in men who exercised at least five times per week. "Despite the high relative risk, the absolute excess risk of sudden death during any particular episode of vigorous exertion was extremely low," they noted, adding that the benefits of exercise clearly outweigh this small risk (N. Engl. J. Med. 343[19]:1355-61, 2000).

Exertion may trigger sudden death by destabilizing plaques or by activating the sympathetic nervous system and decreasing vagal activity; raising susceptibility to ventricular fibrillation. However, regular exercise both protects against plaque rupture and improves basal vagal tone.

Congestive Heart Failure Tx

Experts now agree that [beta]-blockers are a key part ...