June progress: improved aerobic capacity and fat oxidation

June continued the high-volume theme from May — 1,049km of cycling, slightly down in total but up in average weekly volume. The month was bookended by the 600km Wander Wye Audax in the middle, which dominated the training calendar. Like all the long events, recovery took significant time — a full week in this case before I felt properly back to normal.

Almost entirely Zone 2

Almost all my sessions this month were low intensity. The 600km event required substantial rest before and after, which meant June was largely structured around that one big effort. The extended low-intensity focus gave a further increase in aerobic capacity — which showed up clearly in the VO2Max lab test results.

VO2Max: lab results vs Garmin estimate

This month produced an interesting and instructive discrepancy. My Garmin-estimated VO2Max held at 48. But a lab test gave a result of 45 — noticeably lower.

The lab test is more accurate. The Garmin algorithm estimates VO2Max based on pace and heart rate patterns, which can be flattering when you're doing a lot of steady aerobic work. The lab test measures actual oxygen processing capacity under controlled conditions.

The drop from my earlier lab result reflects the almost total absence of high-intensity work in recent months. VO2Max responds to Zone 5 training. I've been doing almost none. This is a known trade-off: I've been building the aerobic base at the cost of top-end capacity. For a 1,200km endurance event in August, that's the right trade. But it gives me something to address in the off-season.

Fat oxidation — the real win

The most significant result from June came from the VO2Max lab test: my fat oxidation had improved dramatically. Even at moderate intensities, I'm now burning a much higher proportion of fat relative to carbohydrates compared to my December baseline. This is exactly what months of consistent Zone 2 training is supposed to produce — and seeing it confirmed in lab data was genuinely satisfying.

For a multi-day endurance event, improved fat oxidation is arguably more important than VO2Max. It means I can ride for longer on stored fat before needing to fuel with carbohydrates. The limiting resource in a 1,200km event isn't aerobic capacity — it's how efficiently you can manage your energy stores across multiple days.

Full VO2Max and DEXA scan results →

Strength training

Dropped off again in June. Weight training and high-intensity work continue to be the first casualties when cycling volume and recovery demands increase. Not ideal for bone density or lean mass, but the focus remains on the August event.

Body composition

Weight held at 94kg. The June DEXA scan showed slight improvements in body fat percentage and bone density compared to the December baseline — modest, but in the right direction. Full results in the DEXA scan article.

Looking ahead to July

July will see a deliberate reduction in volume — a taper ahead of the 1,200km Paris-Brest-Paris in August. The aerobic base and fat oxidation improvements are in place. The priority now is maintaining what I've built while arriving at the start line fresh. The one thing I can't afford to neglect in July is keeping some high-intensity sessions going, even at reduced volume.