By Dr. Jack Daniels
There are several considerations relative to outdoor running in cold weather.
Has there been snow on the ground and have sidewalks or streets plowed for snow? The problem here is that it is usually safer to run on a couple inches of snow than on a plowed or scraped surface which can be slippery. Stay off of ice when possible.
Relative to cold air: with any out-and-back running, run against the wind going out so the return home is warmer. Problem with going with the wind to start is that it might get warm enough to lead to some sweating so the trip home against the wind is likely to be freezing (wind against the wet surface).
Breathing cold air is not so bad. People sometimes think the cold air will freeze the lungs, but our lungs are great at handling cold air (freezing tissue not likely, but cold air can be very dry and heavy breathing of cold, dry air can cause drying of some tissues). Avoid rapid breathing rhythms and try a 3-3 rhythm (3 steps breathing in and 3 steps breathing out). When working harder the rhythm will have to speed up to 2-2 rhythm.
I’m not sure what temperature I would suggest avoiding relative to outside running. I don’t have specific data, but temperatures in the 20’s and 30’s Fahrenheit are not real problems (I do it often here in Upstate NY). Consider cross country skiers who certainly compete and breathe hard, often in very cold conditions. Skiers may be the ones to ask for further advice as they certainly deal with it during all types of workouts.
Consider treadmill training. I realize some people think negatively about treadmill running but it can be very beneficial. I once coached a marathon runner who had run a few 2:12 marathons and moved to an area where long runs outside were not fun. He ran a 20-mile run on his treadmill once a week for 12 weeks. He eventually went on to New York City and ran 2:09 (2nd place overall). If you can mentally handle 2-hours each week of treadmill running, 26.2 miles outside will fly by, I am sure. I used to have my college XC teams (in upstate NY) do a couple treadmill workouts each week for 6-weeks and they ran great.