Goal: I’ll be 50 this year, so let’s do something 50’ish…
we need to build endurance for this, so i’ll focus on z2 training
i register at local gym, i start with 1/2h biking, 1/2h rowing every day, 1 day rest. In the meantime i follow Decathlon training plan “hilly trails” where i replace every easy runs by z2 workouts.
In 3 weeks, i already see progress: I can run on a treadmill for 1h at z2. A run done in august at 50% in z4 is done in February with only 30%time in z4.

I use intervals.icu for data analysis. Following fitness graph, monitoring load and fatigue. I soon realize that z2 workout + 1 big run during the weekend is not sufficient to maintain proper load and enhance fitness. (fitness is seldom in the green). So i crank up the daily workout a little.
Apparently the deal is to have daily load equivalent to fitness goal, evenly spread throughout the week. I find it difficult to fit my week-end big fun run…
I end February with a test marathon : i take a train to Villefranche-sur-Saône and run back home following the river. Unfortunately, i am unable to stay in z2 ( i got lured in a faster pace by the easy flat surface), at 20k legs are dead, the rest of the run is a real struggle. Still manage to set a PB.
So far i am doing a daily 1/2h biking, 1/2h rowing and 15min z2 running to get used to that slow easy pace. My rest HR is slowly going down.