Does training for a marathon make you healthier?
I have four months to train for the BYD Singapore Marathon, a five-hour target, a Garmin full of estimates, and Dr. Varun Reddy keeping the science straight. We are tracking what happens to my fitness, muscle, strength, recovery, and health—and publishing the useful parts, including the mistakes.
Where the training actually stands
Day 2 of Week 8, Build phase. 0 of 5 planned sessions and 0 of 46 km logged so far this week.
What's been written so far
The plan starts Monday — and it already changed once
Before I ran a single step, I re-read my own training plan next to the numbers a physiologist would use, and didn't love what I saw. What changed, and why the doctor review isn't even the reason.
Why I'm doing this
A marathon has a finish line. Health doesn't. This is the premise, the five-hour number, and why I'm treating my own body as the data set.
Why a marathon needs a second opinion
I can put together a training plan that looks correct on paper. I can't tell you what it does to a 40-year-old's blood pressure. That gap is why Dr. Varun Reddy is involved in this project.
What's actually being measured
The athletic goal is simple: 42.2 km in 5:00. The health outcome is not. VO₂ max might improve. I might lose muscle. Some numbers may do nothing interesting at all. Those are all valid results. The job is to measure carefully, adapt the plan when reality intervenes, and resist turning one person's story into a universal prescription.
The plan is already a v3
Current plan: Version 3, the adaptive plan, effective 10 Aug 2026 (Week 1, adopted retroactively). Latest revision: v2 → v3, after an exercise-physiology critique and a coaching critique of the starting plan. Short reason: v2's peak put two-thirds of a week's mileage into a single long run — the classic recreational-marathoner injury signature — so v3 caps the long run by time, spreads load across a midweek medium-long run, and adds quantified green/amber/red gates.
What I thought → what Dr. Reddy thought → what we did → what happened
The recurring framework for when Dr. Reddy and I materially disagree. Here's the first instance — still short one voice, because his review of the plan hasn't happened yet.
What VO₂ max is—and what my watch is about to guess
My Garmin will start estimating VO₂ max the moment it has enough run data, using an algorithm, not a lab. Before those numbers show up on the dashboard, it's worth knowing what they actually mean — and what they don't.