Self experimenting

 On Monday I went to the gym armed with a heart rate monitor, a pulse oximeter, a pencil and a sheet of paper. I walked past the weight room and stepped onto a machine I almost never touch — the treadmill. My own poor handwriting lined up my plan for the next hour: Three minutes at 2 mph, three minutes at 3 mph, three minutes at 4 mph, and so on up to 10 mph, with a three-minute walking rest between each faster interval. After 6 mph (which to be honest is about as fast as I ever run outside), I only bumped up a half mile per hour for each increment. It wasn't all that scientific, but I wanted to satisfy my own curiosity in a controlled setting. Could I boost my heart rate to something higher than 160 beats per minute? What is my blood oxygen saturation at a fairly typical aerobic pace? Can I run at six-minute-mile pace for any length of time? I felt as nervous as I used to at the start of races — anxious that I would either shoot off the back of the treadmill or pass out or both.

Standing there, nervous, at 5,100 feet above sea level, my SpO2 was 99 percent and my heart rate was 77 bpm. At 2 mph my heart rate climbed to 88, and my SpO2 dropped to 97 percent. During each interval the oxygen saturation reading continued to fall, in steady increments. 93 percent while jogging at 5 mph with a heart rate of 131 bpm. 91 percent at 6.5 mph with a heart rate of 152. 88 percent while galloping at 8 mph with a heart rate of 171. (171! I haven't seen that in a while.) By the end of the third minute, my heart was still beating strong and my legs felt fantastic, but dizziness was circling around the edges of my mind.

At 8.5 mph, sweat was spinning off my body like a rotating sprinkler. I felt bad for the lady wearing slacks and a nice blouse while walking on the treadmill next to me. At 9.5 mph my heart rate boosted to 181. This felt like an enormous victory. That's my generic maximum heart rate — 220 minus 39. I clasped my left hand around my right wrist to steady it as much as possible. The SpO2 reading was 84 percent. Droplets of sweat spun around me, defying gravity. Dark rings crept into my field of vision. I wasn't nauseated and I wasn't in pain, but damn it, I was definitely going to pass out. I pounded all of the buttons and blindly lowered my speed to 3 mph. For the next three minutes I hobbled along, smudging all of the pencil markings in sweat as I shakily recorded my findings.

"Probably the reason I always feel like there's not enough oxygen in my blood, is because there's not enough &#! oxygen in my blood."

After those three minutes ran out, because I am above all a masochist, I bumped the speed up to 10 mph. Six-minute mile! Six-minute mile! I was only able to hold the speed for two minutes. I couldn't hold my hand still to test my SpO2 with the pulse oximeter. It took every last ounce of concentration just to maintain my position. I mashed at the buttons until the treadmill slow downed down enough to gently nudge me off the back of the machine. I didn't even bother with the planned cool-down. I just stumbled around on the wooden floor, watching late afternoon sunlight stream through the windows, saturated with bliss. Was this hypoxia? The rapture of the deep? As warmth coursed through my blood, I decided I'd just received a dose of the hormone my body doesn't produce as much of as it once did, because there's no real need when my muscles are already conditioned for more than wheezy soft-pedaling ... endorphins.

 The best I can gather from recent research is that doing aerobic exercise with blood oxygen saturation in the 80s isn't the worst thing, but it's not entirely normal, either. The cause could be an exhausting number of things — obstruction in my lungs, an issue with my heart, poor breathing technique, and on and on. I want to gather a little more data and insight before I go down yet another medical road. My endocrinologist and allergist have helped improve important health issues for me, but this one — the one where I breathe poorly and feel badly while exercising — is still in place and as nebulous as it's ever been. I'm wavering between "Just ignore it and maybe exercise a bit less and try to stop complaining so much," and "Spend all the money, see all the doctors."

While I make up my mind, I'll continue to gather data, mainly for my own peace of mind. When it comes to delusions of control over a chaotic world, perceived patterns make a wonderful placebo.

 Boulder's local ski area opened on Wednesday, and I've been feeling a little FOMO for snowy adventures. Election Day was another frazzled mess of work deadlines and fretting, so I was in need of some hypoxic relaxation. I took the fat bike to Rollinsville and set out for what turned out to be a 26-mile, five-hour ride over two mountain passes. I felt refreshingly good — dare I say better than I have in about a month. The weather was sunny, almost calm, and 22 degrees. Just perfect.

 I continued to take SpO2 and heart rate readings along the way, although this outdoor ride at 9,000-11,000 feet with snow resistance is even less scientific than my treadmill test. Still, the readings fairly reliably measured my "feels like" status. When I still felt fierce and strong, I saw numbers in the low 90s. When I felt myself faltering, I started seeing 80s. My heart was working like a champ, though, with plenty of time in zone 3 and even zone 4. Grinding through several inches of snow up a 10-12 percent grade requires that level of effort, hypoxic or not.

 The descent into Pickle Gulch was the epitome of fun snow biking — a solid base masked by several inches of powder, so I could rip at top speed over a surface as soft and silent as water. I'd had a good climb and a fun descent, and was nearing cloud 9 of Jill Heaven, so I wasn't about to stop there. I turned up Apex Valley, a daunting climb even when it's dry summer gravel. There were moments when I thought I might black out or slip off the back of my bike as it crawled up the steep grade, but my heart kept beating, so I kept grinding.

 Near the top I encountered a California couple with a strange armored vehicle. They were standing outside in the sunshine and chatting with a fast-talking local man on a snowmobile. The man rattled off a barrage of facts about this luxury expedition RV he didn't even own, while simultaneously peppering me with questions about my bike. The California couple took this break in their part of the conversation as an opportunity to pack up their stuff and leave. Before they climbed into the cab, they told me they'd tried to drive over the hill, but the snow was too deep, so they turned around. I was surprised, as it seemed like only a skiff of snow covered the road, but I'd also been riding the very good trail that this heavy machine made for me. Apparently this EarthRoamer costs $1.5 million. Looks cozy. It's probably your best chance to survive the Zombie Apocalypse. But can it cover as much ground as a fat bike? No. No it cannot.

 Past the EarthRoamer track, the chatty local's snowmobile track went for another mile. This track was much less rideable, but I gave it my best effort. There was so little wind that it felt almost hot at this altitude, even though temperatures were in the 20s or lower. The air was crisp and dry, and I felt like I was back in Alaska, deep in the Interior, riding the Poorman Road to Ruby. So sublime.

Once I hit the descent, there was no track at all. All that remained was pristine snow, deeply piled in wind-driven waves. I'll admit, I wasn't expecting to have to walk three miles and 1,700 vertical feet downhill, nor was I expecting to continue to gasp for oxygen as I pulled my wheeled anchor and tired legs through thigh-deep drifts so late in my "short" ride. But this unanticipated effort didn't make me any less happy.


If anything, I was even more thrilled, and counted my blessings. When it's summer, this road is a river of babyheads. There is nowhere to look but down, while bouncing over a jackhammer of rocks and hanging on for dear life. When it's winter, walking at 2 mph, I finally noticed all of the stunning scenery. I glanced at my heart rate monitor. 151 bpm. When I was walking on the treadmill at 2 mph, my heart rate was 88. "When I mark this down on my spreadsheet, it's going to kill the pattern," I thought.

 Oh well. I need to get used to the reality that I may never find the answers I seek. The only concept I can easily grasp is that I'm happiest when I'm in motion. Even when I feel physically weak and bad, and even when an expected fast descent falls under some strange microclimate to be utterly buried in snow, I'm still happy. Is this another shot of endorphins? The rapture of high altitude? Maybe, just as some days are inexplicably bad, others are inexplicably exceptional. Just as some descents are effortless and flowing, others are deep and arduous. Maybe there's no logical reason for the difference. Maybe all the experimenting and questioning is meaningless. Maybe I should ... just ride.