John Sherwood was advised to run 14 years ago after a heart attack and a bypass surgery landed him in the hospital.

His doctor recommended a regular exercise routine, so Mr. Sherwood, then 58, began running. He continues to run on the treadmill a few days a week and even regularly works out with weights.

But Mr. Sherwood began to have second thoughts about this exercise regimen this fall when he learned about the death of "Jogging" Joe Shafran, who had written a column about running in the Maryand Gazette. Mr. Shafran, 81, was running on Jennifer Road when he collapsed and later died.

Mr. Shafran's death made Mr....