Evidence that shivering and exercise may convert white fat to brown — Garvan Institute of Medical Research

 "We found that exercising for an hour on a bicycle at a moderate level produced the same amount of irisin as shivering for 10-15 minutes," he said.

"We speculate exercise could be mimicking shivering -- because there is muscle contraction during both processes, and that exercise-stimulated irisin could have evolved from shivering in the cold."

Evidence that shivering and exercise may convert white fat to brown — Garvan Institute of Medical Research