Last week, I wrote up a summary and analysis of John Korir’s training for the 2025 Boston Marathon. He has a public Strava profile, so it’s all out there for someone with the patience to comb through it.
One thing that I wasn’t able to see previously, though, was the details of his Tuesday workouts. Most of his activities loaded fine on the Strava website – with a map, splits, and details. But most of his Tuesday workouts just didn’t look right.
I realized later that if I went into the mobile app – because Strava presents slightly differently on the mobile app and the web – the workout details were available. The only annoying this is that you can’t navigate directly to an activity. You have to literally scroll back in time from today.
But last night, I sat on the couch while my wife watched TV, and I wrote up the details and took some screenshots of all of these workouts. And with that, I put together the details of 16 weeks of workouts from December 31 through April 15.
Keep reading for the details below.
A Recap and Some Context
First, a brief recap of his overall training to provide some context. You can read the full summary here.
In a typical week, Korir ran 120 to 140 miles. He spent about six or seven weeks at peak mileage before taking a longer, gradual taper.
In a typical week, he ran six days a week with Sundays off. Tuesdays were for workouts. Thursdays were for fartleks or tempo runs. Saturdays were long runs (5:XX/mi). The rest were easy runs to fill in the mileage.
Almost every day included an easy double – around 6 or 7 miles. During peak weeks, Mondays and Wednesdays also included an easy triple – also around 6 or 7 miles. His main easy run for the day (~13 miles) would be at a faster pace (6:XX/mi), but these extra miles would be much slower (8:XX/mi).
He typically did a 2 mile warm up and cool down before workouts at a slow pace.
With that context in mind, let’s walk through his workouts during this training block.
Based on his previous personal bests – 2:02:44 at the 2024 Chicago Marathon and 58:50 at the 2024 Ras Al Khaimah Half Marathon – a pace of ~4:40-4:45/mi would be roughly marathon pace and a pace of ~4:30/mi would be roughly threshold pace.
B-15 Weeks: 3x3000m Threshold
Korir was coming off of an extended break in December, and at the end of the month he was building his mileage back up. This was one of his first workouts after that break.
The workout was 3x3k with around 70s rest between reps. His pace got progressively faster – starting out around 4:40/mi and working down to 4:30/mi towards the end.
So this is basically a threshold workout with cruise intervals. Relatively speaking, this was a lighter workout for him – as you’ll see with the weeks to come. The total volume is around 9k of work in less than 30 minutes.
B-14 Weeks: 10x1600m Threshold
The following week, things got tougher. This was one of the few workouts where had actually labeled the workout in the Strava activity – 10x1600m.
He did 10 reps, with an average pace of around 4:30/mi. His watch auto-laps at the kilometer mark. In most of the reps, you can see that he starts out closer to 4:30 and in latter part of the mile he sped up closer to 4:20/mi. The rest was about 60 seconds, jogging.
So this was another threshold workout. Shorter intervals than before (1600m vs 3000m), more total work (16k vs 9k), and a slightly more aggressive pace.
B-13 Weeks: 10x1000m Threshold
This next week was the first of his big 140 mile weeks. The workout was similar to the week before, but slightly less volume and a slightly more aggressive pace.
10x1000m, 45 seconds jogging rest. His pace started around 4:30/mi for the early reps, and it increased to ~4:25/mi for the last few. So maybe a touch faster than threshold, but in the same range.
B-12 Weeks: Double Threshold-ish
This was the only day that he logged two workouts in one day.
Both workouts were out on the road. They were longer sessions with periods at around marathon to threshold pace. The reps didn’t follow a simple pattern, so you might call this more of a fartlek. But that’s just semantics.
The first run was a total of 17.5k, with reps varying between 1.5k and 2k in length. Between each rep, he slowed down for a 60 second jog. This route was very hilly, and the pace varied between 4:35/mi and 4:55/mi.
Later in the afternoon, he did a shorter run. This one was 7 miles long, and the intervals alternated between 0.5 miles and 1.0 miles. Still 60 seconds of jogging rest. And the pace was a little more aggressive – 4:25-4:35/mi.
B-11 Weeks: 10x1000m Progression
This week, Korir did another 10x1k workout. But this time, he started off a little slower and progressed down to a faster pace.
The first couple reps were around 4:40/mi – closer to marathon pace. He got faster in the middle, and the last few reps were below 4:20/mi pace. At that point, he’s likely closer to 10k pace than threshold – but not quite all the way down to VO2 max pace.
In this workout, he took 45s of jogging rest between reps.
B-10 Weeks: Tempo Run
Usually, Korir did tempo runs on Thursdays – this was the one week that he did one on Tuesday.
After a two mile warm up, he did 18k at tempo over a hilly route. The route started uphill, and his pace early on was ~4:45/mi. The second half of the run was net downhill, and his pace was closer to ~4:30/mi.
With the hills, you could probably net that out to roughly marathon pace effort. He finished up with a two mile easy cooldown.
B-9 Weeks: 16x1000m On/Off
In this workout, he alternated between marathon pace and an up-tempo easy pace.
The full workout included 16 1k intervals. The first rep was around marathon pace (~4:45-4:50/mi). Then he took a 60s walking rest. Then he did another 1k interval at ~5:25/mi. This pace is closer to his long runs – slower than marathon pace but much faster than a typical easy day.
He repeated eight sets of that for a total of 16k.
B-8 Weeks: 8x2000m MP to Threshold
For this workout, Korir ran 8 intervals of 2km each. In each rep, he started off a little slower – closer to 4:40/mi – and throughout the rep he picked up speed – finishing closer to 4:30/mi.
In between reps, he took a little under 60s of rest – a mix of walking and jogging.
At 16km of total work, this is one of his longest workouts (similar to the 10x1600m from earlier).
B-7 Weeks: 4 Sets of 1600m, 800m
For this workout, Korir first ran 1600m, took 75 seconds jogging rest, and then he ran 800m, and then he took another 75s jogging rest. He repeated that for four sets.
Each set is 3200m – for a total of 12,800m of work. A little less volume than the previous week, but his pace was more aggressive today – ranging from 4:30/mi to 4:20/mi.
This was also the last of his big peak weeks. He ran 145 miles this week, and he slowly tapered off from here.
B-6 Weeks: 400m Repeats
This workout was just a massive set of 400m repeats – 25 of them. I guess it only adds up to 10km of work, and he did some bigger workouts than that. But counting the laps, it just seems like a ton of work.
Between each rep, he took about 40 seconds of rest. So this was low rest – shorter than his other workouts. And his pace was around 65 to 70 seconds per quarter.
Overall, it probably averaged out to roughly threshold pace – but some were a little faster. So this was short reps, but not a super fast speed workout.
B-5 Weeks: 6x2000m
This week it was back to longer cruise intervals – 6 x 2000m reps. 60 seconds rest between each rep.
His pace today was closer to 4:40/mi. So a little slower than some of the other days. He also took the rest of this week off following this workout – so maybe he was a little burnt out here.
B-4 Weeks: 10x1000m
If he was burnt out the week before, he was back at it the following week. After taking most of the previous week off, he ran 120 miles this week and did 10x1000m.
He started out around marathon pace (4:45/mi) and progressed down to threshold pace (4:30/mi). He took ~65 seconds rest between reps.
B-3 Weeks: 8x1600m
At this point, Korir was clearly starting to taper down. He ran 105 miles this week and capped it off with a 19 mile long run (down from his usual 22-25 miles).
His Tuesday workout was 8x1600m. The pace was a little faster than threshold – 4:30 to 4:20/mi. And he took 60 seconds rest.
B-2 Weeks: 5 mile tempo run
This week, he took his mileage down to 78 miles and ran a 15.5 mile long run.
Instead of a track workout or fartlek, Tuesday was simply a short marathon pace tempo. After his usual warm up, he did five miles at ~4:40/mi.
B-1 Week: 10x1000m
And here it is: the final workout.
10x1000m. 60 seconds rest. Threshold pace or slightly faster (4:30-4:20/mi).
This was the first workout I saw when I started looking through his Strava history. Someone on Threads had commented that he never ran faster than 8:00/mi the entire week before Boston.
And that was true of the rest of the week. But he slipped this little workout in the Tuesday before Boston. Just a little speed before the big day.
Common Threads and Takeaways
Although things varied a little bit from week to week, there’s a lot of consistency here. And it’s really pretty simple.
For the most part, he targeted threshold pace. Some days were a little slower, closer to marathon pace. Some days were a little faster. Some days started out slow and progressed to the faster end.
But he rarely had a rep that was faster than 4:20/mi. And there was nothing in this series of workouts akin to a VO2 max or faster workout.
He did a lot of volume. It helps that he’s fast, so he can knock them out quickly. But his workouts typically ranged from 10k to 16k of total work. That’s just under 30 minutes on the shorter days and just about 45 minutes on the longer days.
Time wise, that’s about the same as some of the beefier workouts in Jack Daniels 2Q plans. But it’s a lot more distance, because he’s covering those km’s at ~2:45/km.
Notably, he didn’t do any extended tempo runs at threshold pace. I’m a fan of the Jack Daniels style cruise intervals, Korir’s training seems to fit that pattern much more than the longer threshold runs in Pfitz.
During the workouts, he mixed up walking and jogging rests. Some were clearly walking (~15:00/mi), while others were either a very slow shuffle or a walk that turned into a jog. But it never appeared that he took standing rest at all – he kept moving.
When you put it all together, here’s the basic recipe for his training:
- Run a lot of miles, two or three times a day
- Do a threshold workout every week, mixing up shorter and longer cruise intervals
- Do a tempo or fartlek on Thursday (marathon pace, give or take)
- Do a long run on Saturday (uptempo, but nowhere near marathon pace)
- Take easy runs at a moderate pace (6:XX/mi)
- Run all the rest at really slow paces (7:XX-8:XX/mi)
And that’s about all there is to it.
Clearly, the rest of us can’t just copy and paste his training. If you’re not already a 2:10 marathoner, you’re simply not going to be able to put in this kind of work at these kinds of paces.
But the basic playbook is definitely something that we can all implement:
- Run as many miles as you can handle
- Incorporate threshold running and some tempo work each week
- Do an up tempo long run
- Run everything else easy
And really, that’s the takeaway from reading either Pfitz Advanced Marathoning or Jack Daniels Running Formula. They each put a little different spin on things, but at the end of the day this is what their philosophies look like in practice.