Prologue: New block, new language — from %Max HR to %LTHR
This training block starts with one important change. I’ve shifted my Garmin training zones from percentage of maximum heart rate (%Max HR) to percentage of lactate-threshold heart rate (%LTHR).
Why bother changing something that has worked for years?
Max HR tells me where my ceiling is. LTHR gives me a better reference for where my working limits actually are. For marathon training, that makes the zones more individual: recovery stays genuinely easy, aerobic work sits below LT1, and tempo/threshold sessions can be prescribed relative to LT2 rather than percentages of a maximum.
There is a catch.
My old Garmin Zone 2 and my new Zone 2 don’t mean the same thing anymore. Runs that previously looked almost embarrassingly slow may now fall exactly where they should. And LTHR itself isn’t carved in stone—it needs to be validated and adjusted as fitness changes.
So this block begins with a small experiment: less obsession with pace on easy days, more attention to physiological effort.
Week 1: Building the Engine
Week 1 is done. 19 to go.
The objective was simple: build the aerobic engine without trying to prove that I already have one.
59.2 km of running, plus 2 strength sessions. Most of the week was deliberately easy—proper easy, where pace is allowed to leave its ego at home and heart rate decides the effort.
Tuesday added 4 × 200 m hill repeats after the aerobic work: a little strength, mechanics and speed without turning base building into race preparation too early.
Wednesday was recovery. Very easy. The kind of pace at which Garmin probably wonders whether you’ve accidentally selected “running.”
Saturday was the first real test: 14 km aerobic + 3 min recovery + 4 km continuous at marathon effort.
The final 4 km came at 5:00/km, almost exactly around the 4:58/km required for a 3:30 marathon, despite Pune generously providing 86% humidity.
The encouraging bit wasn’t the pace.
It was reaching marathon effort after 14 km and still being able to run controlled, rather than forcing it.
Week 1 takeaway
Speed isn’t the project yet.
Durability is.
Over the next 19 weeks, the objective is to gradually make 4:58/km feel less like a pace I can run—and more like a pace I can keep running.
There will also be another metric worth watching: whether the same easy effort gradually produces more pace, and whether marathon pace gradually demands less cardiovascular effort.
That, more than one fast workout, will tell me whether the engine is actually getting better.
59 km down. Ahmedabad is still a long way away. Exactly as it should be.
