Training for a sub-3 marathon

Having unexpectedly broken three hours for a marathon, I am curious to understand how I did it. Since my first marathon, Tokyo 2014, my times have been as follows:

Tokyo	Feb 2014	3:16:18
Kyoto	Feb 2016	3:10:22
Oshima	Dec 2016	3:26:00
Senshu	Feb 2017	3:08:13
Osaka	Nov 2017	3:10:03
Himeji	Feb 2018	3:02:38
Shonan	Dec 2018	2:57:36

I was unable to prepare “properly” for the three autumn races, Oshima (which is very hilly), Osaka, and Shonan, as I always focus on short distance triathlons until early November when the season ends. Apart from the occasional middle-distance triathlon, I generally only run 10 km before my winter running season. This season, I was planning to focus on Kochi Marathon in February, with Shonan just being one step on the way to breaking three hours. So what happened?

After Himeji Marathon in February 2018, almost all my running was around 10 km as I was focussing on Olympic distance triathlons. I did a middle distance triathlon in May and another in June, but only one 20 km training run for these races (a local half marathon race). In the 9 months up to Shonan Marathon, I only did 6 runs over 20 km, as follows:

May 20, 20 km (Nagaragawa triathlon), 1:30:45
Jun 2, half marathon, 1:29:40
Jun 17, half marathon (Goto triathlon), 1:41:17
Oct 14, half marathon 1:25:05
Nov 15, training 37.25 km, 3:04:14
Nov 25, training 22.25 km, 1:44:02

So how on earth did I run a marathon in under three hours? I think the key was my 10k fitness. I ran a slightly long Helsinki 10k in August at 3:45 pace, and then the Gold Coast triathlon 10k in September at 3:54 pace. I followed this with the Namban 10k on Nov 4th at 3:49 pace, and the Miyazaki triathlon 10k on Nov 11th at 3:47 pace, my fastest ever triathlon run. For training, I was mostly running 10 to 13 kilometres, 3 to 4 times a week, as well as swimming 3 times, and cycling 4 to 5 times a week.

This doesn’t look at all like conventional marathon training. I have a few training plans from the internet which all seem to follow the same idea of one long run a week which gradually builds up to something like 35 km, and then lots of somewhat shorter runs. I did something like this leading up to Himeji Marathon last winter when I got fairly close to 3 hours. In the 6 weeks before that marathon, I did a 20k race and two 30k races at 4:15 pace or thereabouts.

In contrast, I did 11 races in the five months up to Shonan Marathon, but mostly shorter distances. Including triathlons, I did the following races:

July – 2 x 10k
August – 2 x 10k
Sept – 1 x 5k; 2 x 10k
Oct – 1 x 16k; 1 x half-marathon
Nov – 2 x 10k

When I look at all this, it doesn’t seem very much quantity. However, it confirms what some people say: you don’t need to do a lot of long, slow running to run a good marathon. I mix trail running in the hills behind my house, with moderate pace running on hilly roads (usually 4:30 to 4:45 pace)…and that’s it. Shonan was the first marathon I have entered with only one long distance training run behind me (an ill-advised 37 km run which damaged my calves for ten days). The main thing that stands out for me is my good 10k times, especially in triathlons. As they say, if you train slow, your will race slow. Pushing yourself hard in 10k races might be more effective than pounding your body in lots of long training runs.

PC170410 One of my favourite runs, along Isshiki Beach