Altitude and running
Running introduced me to a health and fitness measure I had never heard of: VO2max.
My Garmin tracked all sorts of things. Heart rate showed up immediately, while other numbers appeared only after the watch had gathered enough data. One day the app announced a VO2max of 48. Was that good or bad? I had no idea. A month of daily runs later, it read 52. Up seemed good, but I decided to find out what the number actually meant. I felt like Alice in Wonderland: every answer led to something stranger, and my watch seemed to know the rules better than I did.
The more I read, the more interested I got. Some of it connected with things I already knew.
Go above 3,000 meters in the mountains and you may encounter altitude sickness. The air is thin: less oxygen reaches your blood with each breath. You breathe faster and still can't get enough. Headaches, vomiting, dizziness, disorientation. The strain goes beyond breathing. Your blood and circulation have to adapt, too, with changes in red blood cells and hemoglobin affecting how oxygen reaches the rest of the body. Given time, your body adjusts to the new conditions and copes better with the shortage. It also remembers the experience: a second or third mountain trip can feel easier than the first, with a quicker, less painful adjustment. That's why you climb in stages. Reach a new altitude, sleep there, and let your body adjust. Then climb again, and spend another night.
The higher you go, the harder it gets. Around Everest Base Camp, at roughly 5,340 meters, the available oxygen pressure is about half what it is at sea level. Keep climbing and it keeps dropping. At extreme elevations, supplemental oxygen can make an enormous difference. A few steps, then more breathing.
Not every climber uses it. Some carry cylinders; others manage without. I read about the American mountaineer Ed Viesturs, who climbed all fourteen 8,000-meter peaks without supplemental oxygen. The skill and nerve were impressive enough. Having a body that could cope without extra oxygen must have made him the envy of plenty of climbers.
People who live high in the mountains, including Tibetans and Nepalese Sherpas, have genetic adaptations to those conditions. Their breathing and blood respond differently to altitude, and they grow up living with less available oxygen. That's why Sherpa porters can work for so long without oxygen cylinders and still feel reasonably well.
So our ability to cope with limited oxygen depends a great deal on our genes. Like many other abilities, it can be trained. But each of us has a ceiling we were born with.
In running, VO2max describes the maximum rate at which the body can use oxygen. It's one part of endurance potential, and partly a genetic lottery. Yet training can help us develop the capacity we have.
The name breaks down neatly: V for volume, O2 for oxygen, and max for maximum. VO2max is the maximum volume of oxygen your body can use in a given time.
The thrills of VO2max
Here's a little more detail. Relative VO2max is measured in milliliters of oxygen per kilogram of body weight per minute: ml/kg/min. It describes the maximum rate of oxygen use during intense exercise. Watching it rise can be one way to follow improvements in fitness.
Beginners often start from a relatively low level, so early training can bring a noticeable increase. Progress eventually slows. Then you hit a plateau, and even a small improvement can take a lot of work and more focused training.
A laboratory exercise test is the most reliable way to measure it. A sports watch estimates it. The estimate is less precise, but I can still follow the trend: up, down, or steady.
My watch's estimate rose from 48 to 59 in the first six months. As I increased the load during the second half of the year, it fluctuated between about 56 and 58. Hard, fast runs often sent it down; easing off brought it back. That seemed to be where I had leveled off.
Experienced, gifted athletes may reach the sixties or seventies, with some elite competitors above eighty. I read of exceptional individuals recording figures of 84 and even 96 ml/kg/min.
Running more, especially at an easy pace, helped the estimate rise, up to a point. Intervals, proper rest, sleep, and nutrition mattered too. A falling number made me wonder whether I was training too hard or recovering too little. Since the figure is expressed per kilogram, changes in body weight affect it too.
I wanted to know how to improve VO2max beyond the usual advice to train and rest. One option is Billat 30-30, named after physiologist Véronique Billat: thirty seconds of fast running, then thirty seconds of easy jogging, repeated in a series.
Still, relax. It's only an indirect measure. Compare different athletes' VO2max scores and you won't know who's fastest or who has the most endurance. Only a race shows how people use their potential. Elite athletes improve their results without changing VO2max. Your colleague who smokes might have the genes for a VO2max of 90 and still fail to run a couple of kilometers. In another life, they might have been a champion.
The carousel
On a long run, thoughts go round and round. We talk about racking up miles, and sometimes we're literally running in circles. Wheels turning, a potter at work, runners circling a track: there's something mesmerizing about going round and round.
I found a mental trick for long distances. I imagine a vast carousel rotating beneath me, carrying me along. Running is simply how I stay aboard. Instead of hauling myself through space, I'm being carried by something larger. The thought is calming. Some turns of the carousel even feel easier than others. My seventh, eleventh, and seventeenth kilometers often feel easier. Knowing that, I look forward to them.
Sometimes that carousel pops into my head on its own. Sometimes I picture it before I start. I tell myself the seventh turn will be easier, and somehow the seventh kilometer brings a little burst of energy.
A ride on an imaginary running carousel is worth trying at least once.
Cadence
The cheetah is the fastest land predator. Over a short distance, it can outrun anything else on land.
An experiment comparing cheetahs with racing greyhounds found that the cheetahs could speed up by increasing their stride frequency. Greyhounds relied more on lengthening their stride, and couldn't match the cheetahs for speed. Something for a runner to think about.
The number of steps per minute is cadence: how often a runner's feet touch the ground. That little word held a clue to speed.
I knew about cadence already, but hadn't taken it seriously enough. After reading about cheetahs, I checked my data. On my best runs it sat remarkably close to 163, with a step length of 130 to 135 cm. Nothing unusual for a recreational runner. On slower runs the cadence was lower, on faster ones higher. There was the clue.
Running speed can be reduced to a simple relationship:
Speed = average step length × average step frequency.
To go faster, I could lengthen my steps, take more of them per minute, or do both.
Unfortunately, my usual response to wanting more speed was to reach farther with each step. A common mistake. What works in sprinting doesn't necessarily suit a marathon. I picked up several minor hamstring strains without gaining much overall speed.
Many coaches cite 180 steps per minute as an ideal. At the 1984 Olympics, coach Jack Daniels - memorable name, very famous coach - observed forty-six distance runners and found only one with a cadence slightly below 180. The others were above it. Recreational runners often turn their legs over more slowly.
Bodies and circumstances differ, of course. Still, that nice round number, 180, became a kind of gold standard for runners.
Working on cadence is slow, dull work. It can look pretty funny, too. One moment I was running like a normal person, reasonably graceful if not particularly fast. The next I was shuffling along, feet a blur of tiny steps.
If I had no interest in speed, I might have left it alone. But I wanted to experiment, so I tried running to a fixed rhythm above 170 steps per minute. A metronome app clicks away, and I match each footfall to a click. Shorter steps, quicker turnover.
Your app or watch probably measures cadence. Take a look. Somewhere around 130 to 160? Then jumping straight to 180 steps a minute probably isn't going to happen. Work up to it in stages. Start with about a 5% increase and get comfortable at that rhythm. As you improve, try a little more, then a little more again, until you find your own limit.
Why bother? I wanted to waste less energy with each step so I could hold my pace longer.
Running with a metronome
A metronome isn't music. It's repetitive and boring. I doubt anyone falls head over heels for this workout.
A few sessions, though, can plant the rhythm in your head. Your feet start to remember it, too.
I set the tempo and a timer, then tried to make each step land on the beat. I set it a little faster than my cadence on my best runs.
I won't forget that sound. The metronome chirped like a mechanical cicada, completely indifferent to how fast I was going. Somehow I was running much faster.
Long afterward, that mechanical insect was still ticking away in my skull.
To escape the clicks, I could use music sorted by tempo: 160 or 170 bpm, for instance, on Apple Music or another service. I doubt many people play those mixes at dinner, but they do the job. If all I want is a beat to follow, though, I'll take the metronome.
I don't have to use a target cadence throughout every run. I can choose one stretch for deliberate practice and spend the rest running at a comfortable natural rhythm.
I have no idea what Kipchoge listens to. In my imagination, though, it's a metronome.
The extra mile
In business, going the extra mile means giving more than promised: three designs instead of two, an unexpected cookie with the coffee, a job delivered sooner or better than the customer imagined. Doing a little more feels good on both sides. In running, you can take the expression literally. I set out to run 10 km, feel surprisingly good, and add another 500 meters, perhaps a kilometer, perhaps a whole extra mile - about 1.6 km. I've surprised myself. It doesn't always have to be spontaneous. It might be a modest weekly target of 50 km instead of 48, something I doubted I could manage and then did.
The distance isn't really the point. The extra effort is. Can I do more than I expected, or am I just checking a box? Can I surprise myself, stop putting things off, and go a little farther?
That feeling of getting past my own resistance is a wonderful reward. From time to time, I give myself an extra mile. A little treat. A little surprise.