This isn't the time to pile on every sweatshirt you own. As your body warms up on your run, you won't need as much insulation, Graman explained. If you're overdressed, you could get too warm and begin to perspire.
"Sweat is your enemy when running in the cold," Graman said. Wet clothes in cold temperatures cause your body to lose heat more quickly, which puts you at greater risk for hypothermia. He recommends dressing as if it's five to 10 degrees warmer outside to allow for a natural increase in body temperature.
Both coaches also suggest wearing layers you can easily take off as your body warms up. (You should remove a layer at the first sign of sweat, Graman added.) Sexton recommends a long-sleeved base layer made from merino wool and an outer layer that zips up (for easy removal) made from a material that's wind- and water-resistant.