Issue 43
The Long Walk Up
Training for 14000 Feet
As a young distance runner, I worked with coaches who taught me something I’m still using: fitness is discipline applied to a particular goal. Not fitness for its own sake — fitness for something.
Today, that something is getting up peaks as high as 4,250 metres with a camera when I need to. Not winning races. Not maintaining a gym selfie. Getting up, making the work, getting down.
I know I can manage 21 km a day in the back country and handle peaks up to 3,000 metres. The difference between there and 4,250 metres — a 15% drop in available oxygen — puts me in the zone where altitude sickness becomes a real concern, aerobic capacity falls off, and acclimatisation time matters. That gap requires capacities I need to build.
Now, in mid-life, I have the self-awareness to know that more than a few ships have sailed — and that some were never even in the harbour. I have no interest in gym memberships or the high-intensity programmes that look like a never-ending dopamine rush. What I’ve built instead is a routine that is sustainable, flexible, and based on what I know works — supported by good research. I pared back the excess. I don’t need a yogi’s flexibility. I need my body to process oxygen efficiently.
I
Zone 2 is the heart of my routine.
It’s the highest exercise intensity at which blood lactate remains stable — around 1.5 to 2 mmol/L — and the point at which fat oxidation is maximised. Most athletes define it by heart rate: 60–70% of your maximum. For mountain walking, the lactate-based definition is more useful. If you don’t have a lactate meter or a coach, it’s the intensity where you can hold a conversation, but not effortlessly.
This measure is not fixed. The longer you train, the higher your lactate threshold rises relative to your age-dependent heart-rate zones. That’s the point.
Zone 2 matters because a long day in the mountains — especially loaded with camera gear — is almost entirely spent at this intensity. The better my mitochondrial function (the efficiency of the power stations inside my muscle cells), the more fat I burn, the slower my glycogen depletes, and the less fatigue I carry into the descent. Training here builds a bigger furnace.
Crucially, I can maintain this load without special diets or recovery protocols.
II
The current fashion is to go hard on strength training. And why not? You look terrific and can talk about reps and maximum lifts and other esoterica. The problem is one of balance.
Too much of one thing limits time for what actually matters: maintaining your aerobic base. Peterson et al. (2010), surveying the research on strength training in bodies over fifty, found that frequency and volume do not significantly predict strength gains — intensity does. Most studies focused on one to three sessions per week. I choose two.
Getting up a hill does not require enormous strength. Getting down one without injury does. Downhill, your muscles lengthen under tension — eccentric loading — which puts considerably more stress on your legs than the climb. The risk of injury is higher on the descent, which is also when you’re most tired.
Targeted eccentric training — Bulgarian split squats, Romanian deadlifts, slow step-downs, and the like — both builds muscle mass and lengthens the fibres, preparing them for the specific demands of descent.
III
VO₂ max — the ceiling of what my body can take in, deliver and use in terms of oxygen — matters even though hill walking never approaches it. The logic is straightforward: the higher the ceiling, the easier everything beneath it becomes.
A higher VO₂ max means a steep section at 3 mph sits at a smaller fraction of my total capacity: less lactate, slower glycogen depletion, faster recovery between pitches. At 4,250 metres, where effective VO₂ max drops roughly 1–2% per 100 metres of elevation above 1,500 m, that headroom is not a luxury. On a long day at altitude, it is the margin between working comfortably and working at the edge.
I don’t need an elite number. I need it high enough that the hills aren’t pushing me into Zone 3 for extended periods — a comfortable aerobic margin on steep ground and thin air.
I get there by swapping one weekly Zone 2 run for a Norwegian 4×4 session: four minutes at 90–95% of maximum heart rate, three minutes of active recovery at 70%. If I’m tired, or if no big walk is coming, I skip it and keep the steady work. The emphasis is on longevity and having the conditioning when it counts — not on grinding out sessions for their own sake.
I choose 4×4s because the research supports them as one of the more effective protocols for improving oxygen uptake. Alternatives exist — 15/15s (15 seconds hard, 15 seconds easy) work well too. You don’t need a smart watch for any of this. If you can speak after the first four minutes, you’re not going hard enough. Or find a hill.
My running coach had me doing something similar decades ago, before the research existed to explain it. He called them 400-metre splits. I ran a lot of them — until my legs failed or I puked up my lunch, whichever came first. The benefit of the recent science is that it tells you which methods work best and, crucially, how much is enough. My coach never seemed to have a limit in mind.
One warning: warm up properly before any interval work — a slow jog or ten minutes with a skipping rope. Cool down afterwards, stretch hips, quads and calves. I use a foam roller. Forty minutes to an hour covers the lot.
This sounds like a lot. It isn’t. The routine takes about four hours a week. Juno and I are not training to be elite athletes. We want to get up that peak and down safely — and make some good images along the way.
A necessary caveat: if you’re unfit or managing a pre-existing condition, talk to a specialist first, and find a good coach. Beyond a certain age, injuries don’t heal on your schedule. You end up on the bench for uncomfortably long stretches. What works for me may look nothing like what works for you.
But the principle holds: science lets you build a tailored plan that supports the life you actually want. The cost is modest. The alternative is hoping for the best, which — in the mountains — is not a strategy I’d recommend.
A Question for You
What would you need to be fit for?
— Johan du Preez
References
On Zone 2 Training
Assessment of Metabolic Flexibility via Lactate and Substrate Oxidation by San Millán, I. & Brooks, G.A.
Peter Attia Podcast — San-Millán explains his full six-zone model and Zone 2 physiology in detail.
High North Performance — good breakdown of San-Millán’s Zone 2 framework with references.
Much Ado About Zone 2 — a 2025 narrative review in Sports Medicine that critically examines the Zone 2 evidence base (a useful counterbalance).
Zone 2 Intensity variability study — cites the San-Millán & Brooks 2018 paper directly in a Zone 2 context.
Episode 201 – Deep dive back into Zone 2 | Iñigo San-Millán, Ph.D. (Pt. 2).
Appropriate Strength Training
Resistance Exercise for Muscular Strength in Older Adults by Peterson, M.D., Rhea, M.R. & Alvar, B.A. 2010.
Eccentric Exercise as Potential Intervention for Downhill Locomotion by Vogt, M. & Hoppeler, H. 2014.
Improving VO₂ Max
Aerobic high-intensity intervals improve VO₂max more than moderate training by Helgerud, J. et al. 2007.