December: Slog

   If you had a butt like a penguin's, you'd waddle too. It's a cold-weather butt – a glorious, drooping repository of anchovies, sea fern, and other metabolic fuels that stoke cheery warmth through the season's worst. Nature's inviolate lesson about a penguin's derriere is that we shouldn't run in winter.

   At least, that's my reasoning as I stare at the fitful rain outside the window. The logic fails. A runner burns up to 12 percent more calories in the cold. A hard aerobic workout lifts the season's gloom from mind and mood like nothing else. It forces blood into ever-cold extremities, urging your body to lay new capillaries like modern plumbing in remote rooms of a creaky house. Cold-weather running builds your cardio base and stamina, the benefits of which – often as not – burst upon you with gratifying surprise when temperatures turn hospitable. Besides, winter workouts prevent penguin butt.

   The trick, of course, is to dial back the distance and frequency of your runs during the miserable months while maintaining their intensity. Yes, intensity is key, and cold-weary runners should note that this means interval training. No other workout delivers the efficiency of intervals, which – praise be – return you indoors all the sooner, showered and dialing for an anchovy pizza. Intervals also force discipline on your workouts since they can be counted, timed, and otherwise tallied. Numbers don't lie; backsliders have to confront their shirking resolve.

   Trouble is, you don't want to sprint from your doorstep, even when the chill is biting at your droopy bum. Cold-weather intervals should begin with a languorous warm-up. Running books typically recommend 4 to 8 minutes of slow going before speed work. Double or triple this amount, according to the day's frigidity and the darkness in your heart. Likewise, resist walking during recovery periods between intervals. Instead, slow to a dawdler's jog, giving yourself luxurious amounts of time for your pulse to drop and your breathing to return to normal.

   Competitive runners will scoff at this advice, pointing out that cold-weather cream puffs like me won't get faster until we work a strategic program for intervals, increasing repetitions and distance in systematic doses. They're right. So give them their heart monitors and stopwatches, and let them fly. The rest of us will use deep-winter months for maintenance workouts. The marvel of intervals is that they accommodate almost any kind of running goals.

   They also scale nicely. You may find yourself adding intervals to workouts to spite the season's boredom and gloom. Winter is a good time to change your training course to something closer to home – preferably a loop or a circuit that allows you to add or cut intervals as your ambitions allow. Mind you, running in circles is neither scenic nor audacious. But this is winter. Suck it up. You can waddle across clover fields in the spring.