Thursday, June 6, 2013

The Nose Don't Lie

Over the last few years, Alison and I have become enamored with our noses. As it turns out, oxygen moves in through your nose, which is quite a handy feature for us endurance folk. Certainly everyone who has ever run, biked, skied, or swam with a head cold knows the perils of shutting your nose out of the process of aerobic respiration: you get fatigued quicker and your pulse rate increases.

But until recently, I never imagined my nose would guide me in a methodical way with my endurance training. It all started two winters ago; while traveling on racing trips I would usually get out the door in the evenings for a 30 minute light jog. I've found a nice run in the evening really loosens me up and flushes out whatever junk I acquired over the course of the day, whether from traveling, racing, or sitting around in a hotel room watching America's Next Top Mode...err, American Choppers. Anyway, a few seasons back I started doing these runs with my mouth closed. Initially it was because I was in central Maine or Northern Wisconsin in early January and the thermometer had a hard time cracking double digits, and I wanted to preserve my lungs somewhat. Breathing through my nose warmed the air more before it got into my lungs, saving me from hacking myself to sleep later that night. I found through this method that I could still run pretty darn quickly; I figured I could run as fast as I wanted with my mouth closed, because I would be inherently limited in that I could only bring in a certain amount of oxygen when only my nose was the conduit. This led to these evening runs being pretty quick.

I kept this up through the end of the season, and when I started my spring training that next May, I found my running pace during longer runs was indeed quite a bit faster. I did some research and talked with my coach about my findings. Turns out, what I had stumbled onto in a rather bumbling manner (isn't that how most training methods are discovered?) is what physiologists call your Aerobic Threshold (AeT). Essentially, this is the point below which you are in a fully aerobic state of metabolism: lots of oxygen coursing through your system, and your respiratory rate can handle the offloading of the CO2 which is produced through your body's metabolic processes, without trouble. Above this AeT however, you slowly begin accumulating lactate in your bloodstream as your respiration can no longer effectively expire the CO2 being produced and a higher degree of glycolysis (carbohydrate metabolism) must ensue to meet the workload. Don't sweat the science too much.

My mistake in these early explorations was believing that the limiting factor in nose-breathing was my nose's ability to INSPIRE fresh oxygen, when in fact the real limiter was its ability to EXPIRE the CO2 from my body. What this nosebreathing "threshold" (i.e., the upper-most intensity you can train while only breathing through your nose) then represents, is your Aerobic Threshold: the point at which your body can no longer maintain a fully-aerobic state of metabolism, and it must shift to a higher degree of glycogen metabolism. Pretty groovy, huh? You can use your nose in place of a $400 lactate meter, or a $20,000 ventilation analyzer, and it's damn near as accurate. Point in fact: when I got my testing done at Seattle Performance Medicine this spring, they marked my AeT (by ventilatory data) at 162bpm; I had been operating on the premise (based on field data by nosebreathing) that it was 165bpm - quite close!

So why is all this useful for the endurance athlete? Spending a significant amount of time at or near your aerobic threshold will allow you to train faster and harder while still maintaining very low amounts of lactate in your blood. And it improves with time and efficiency! Imagine this: today you can run a 9:30min/mile for an 8-mile run; in other words, that's your sustainable "aerobic" pace. But what if you could run that same eight miles at an 8:30min/mile pace, or faster, for the same effort? Interval and high intensity training have one major flaw: you can only do small portions of them, on the scale of 10-15% of your total training volume. But AeT training can occupy a much larger portion, and the returns are probably much greater for the average endurance enthusiast.

How do I gets myself a piece of this magic formula, you ask? First, go out for a run/bike/ski, and close your mouth. Now find the pace you can sustain while only breathing through your nose. Don't fudge it; you shouldn't be breathing overly-rapid or in a ragged way during this - it should be even, sustainable breaths. Chances are this pace will be slower than you're hoping for, but have faith. If you do some nosebreathing training every week (start with 30-40% of your total volume, and increase it with time and comfort), you'll see rapid improvements. Soon, for the same amount of aerobic energy you'll be going farther and faster!

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