A man from Napa County died last week while biking at Boggs Mountain Demonstration State Forest in Lake County. Jeffrey Harrington, 61, suffered a medical emergency and despite help from his friend and medics, he could not be revived. Deputies responded to the 11000 block of Forestry Road in Cobb, California, where medics were performing life-saving measures on Harrington. His cause of death has yet to be determined. A study of deaths during recreational mountain biking shows that more than half were caused by non-traumatic cardiac issues, possibly due to the challenging nature of the sport.