And, for comparison's sake, here are the numbers from the Garmin GPS. Running versus snow biking up Blue Mountain:
Saturday Sled Run
Sunday Snow Ride
(Today on my run: A quick Monday morning jaunt up to South Sentinel Summit. The temperature was -5 degrees with light windchill. I was wearing most of the clothing I'm blogging about today, staying comfortably warm but a little too sweaty. Plus, my hat got soaked. I wonder how that happened?)
Certain types of insulating clothing can often protect against a wide range of weather. But there is a monumental difference in a body’s needs when you add time. I can complete my 20-minute bike commute to work when it’s 10 degrees outside wearing only jeans, regular shoes, a cotton hoodie, thin shell, hat and fleece gloves, and still feel fairly comfortable when I arrive at work. But if I was going out for an eight-hour bike ride in 10 degrees, you can bet I’d be encased in fleece and Gortex, with huge winter boots and three layers of socks. If I wore my commuting clothes on an endurance ride, I would probably die. But why is something that’s good enough for 20 minutes not good enough for eight hours?
But the problem remains — bodies start out warm, and because thermoregulation isn’t a perfect system, will eventually cool down over time. Physical activity helps stoke the furnace (like gasoline on kindling.) But even with an unlimited source of calories, muscles and motivation wear down over time, and the body is forced to slow to a more sustainable pace (big logs, slower burn.) Therefore, the practical way to dress for long periods in the cold is to start out as lightly dressed as possible, burn through the kindling, and then add layers to protect the slow burn as the body cools down.
It makes sense in theory, but in practice, I detest the layering and de-layering process on the trail. I like to keep moving, so I tend to start hot, shed an excessive amount of sweat, and then fight for hours to keep my suddenly damp furnace from fizzling out. Simple folk logic dictates that "sweat kills," but it's never a cut-and-dry situation. There are degrees of manageability, especially when sweat gathers and refreezes on the inside of a Gortex shell, where it limits the fabric's (dubious) breathability but otherwise doesn't do much harm. It’s certainly not ideal but I manage to make it work for me most of the time, by favoring moisture-rejecting synthetic layers and vapor barriers. I can wring the warmth out of lightly damp fleece layer for eight or 10 hours, but as I learned last year in the White Mountains 100 and previous Susitna 100s, this doesn’t work so well for 20 hours or more. As time burns on, my body just keeps cooling, and after a while I am just really, really cold.
Thus, my “one-size-fits-all” Susitna system for a decidedly not-one-size-fits-all world. This is an event that, if I finish, will take at least 30 hours and as many as 48, in temperatures that could range from -40 to +40 degrees, from dry Arctic cold to rain. Temperatures will likely fluctuate ~30 degrees or more during the event, and I'm more likely than not to see some precipitation.
This has become a weekday routine for me, the Rattlesnake Corridor, dragging a heavy sled that sounds like a far-away airplane as it grinds over the icy snow, punching footprints in the soft slush until my legs sink to my knees and I can hardly move anymore. This forced stopping point always happens at nearly the same distance, 5.5 miles. I leave at 5:30 p.m. under the last gray streaks of what feels like hard-earned January daylight, which fades imperceptibly to dark gray and then black above the thick tree canopy. At first I can run "fast" at nearly 6 mph but as the trail deteriorates I "run harder" for a quad-and-hamstring-burning 3.5 or 4 mph, and then, as most trail use fades, finally a full-calf-and-ankle-shredding-1.5 mph slog.