Inigo San Millan, Tadej Pogacar, and the Case for Going Slower
Inigo San Millan served as head of performance at Team UAE Emirates and worked directly with Tadej Pogacar across the Tour de France victories of 2020 and 2021. His research interest, developed over two decades, is metabolic fitness — the specific cellular adaptations that occur at low exercise intensity. His work, popularised by longevity physician Peter Attia, has produced one of the most significant recalibrations in popular exercise thinking in twenty years: the case for going uncomfortably slow.
Zone 2 is defined precisely. It is the highest exercise intensity at which lactate concentration in the blood remains stable rather than accumulating — typically 60-70 percent of maximum heart rate, or the pace at which you can hold a conversation with some effort. At this intensity, fat oxidation is maximised and mitochondrial biogenesis is most powerfully stimulated through sustained PGC-1 alpha pathway activation. The protocol San Millan validates for non-elite athletes is three to four sessions per week of 45-60 minutes at genuine Zone 2 intensity, producing measurable improvements in fat oxidation rates, lactate threshold, and mitochondrial density within eight to twelve weeks.
Why Most Recreational Exercisers Miss It
The practical challenge: most recreational exercisers who believe they are doing easy aerobic work are actually in Zone 3 or 4. Running pace that feels comfortable is frequently above the Zone 2 ceiling. Confirming Zone 2 requires either a lactate meter targeting 1.7-2.0 mmol/L or a heart rate monitor set at 70-75 percent of maximum, and the initial experience of maintaining Zone 2 — often embarrassingly slow — is what produces the adaptation. The 80/20 training distribution that elite endurance coaches now use means 80 percent of weekly volume in Zone 2 and 20 percent in high-intensity intervals, a ratio that athletes who trained at comfortable moderate intensity for years find profoundly counterintuitive but measurably superior.