Marathon Training

The 21-Day Rotating Marathon Training Block

This simple marathon training plan ensures that you get in all essential workouts while optimizing recovery time between key sessions.

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When you’re getting ready to race a marathon, your two main tasks are simple: Expanding the limits of your raw aerobic endurance, and improving your ability to maintain goal pace in the latter stages of the race. To be maximally prepared for these tasks, you need a solid base of mileage, long runs, and regular, specific, high-volume workouts. But what’s the best way to set these up?

With marathon training, managing a burden of ongoing running fatigue while still getting in quality sessions is perhaps the biggest hurdle the event presents to challengers. One effective way to manage this balance is to spread workouts out in a 3-week, 21-day training block.

The Core Concept

While I was training for the 2001 Boston Marathon, a typical New Hampshire winter compelled me to derive most of my higher-end speedwork at indoor all-comers meets in Boston or sneaking in some 400s when the local outdoor track permitted. I was arranging these infrequent sessions somewhat sparsely around a backbone of long tempos, marathon-pace efforts and long tune-up races.

When I later reviewed my training for the race that stands as my lifetime best of 2:24:17, it suggested a system that touches on all of the training paces in a way intended to optimize two training variables: The distribution of the running done at different intensities, and the recovery time between key individual sessions.

This produced a 21-day block, or mesocycle, that includes nine “critical” sessions, seven of which feature a speed element. Not only is it simple – though not easy – to follow, but based on your current fitness level, you can decide how many “blocks” you need before your goal marathon and plan for that race in a surgical way.

I began applying this idea schematically in the early 2000s, when a runner I was coaching from Indiana followed it in qualifying for the 2004 Olympic Marathon Trials and setting a PR at the Trials race itself. More recently, a local runner in Boulder has used the program twice, running 2:47 and 2:46; both times he exceeded his expectations based on his shorter-distance races, but his results fell nicely in line with the long, steady marathon-pace sessions he’d done at altitude.

The Basic Structure

Apart from the core components of 1) sufficient basic endurance (i.e., enough mileage) and 2) long runs of some sort, the three most important elements of a marathon-training program are marathon-pace work, tempo-type running, and faster speedwork, often on a track. While a track racer’s more intense training would slant toward the latter two, as a marathoner, you need to go heavy on the first two without completely neglecting high-end speedwork altogether.

Once a week, you do a speed session totaling about three miles of reps in the range of 3K to 5K race pace. The other key days of each week are a midweek medium-long run, which may include either an embedded tempo run or a fast finish, and a long run, which may include marathon-pace work or a fast finish.

This rotating scheme allows for a total of seven “hard” days every three weeks, with one additional medium-long run and long run at an everyday pace mixed in. This sees you touching on every race pace from 3K to marathon pace, with a heavy emphasis on running fast when you’ve already got some miles in your legs that day.

The 21-Day Marathon Training Block

Week M Tu W Th F Sa Su Mileage
1 MLR SS LR + FF Lower
2 MLR + T MS LR Moderate
3 MLR + FF LS LR + MP Higher


  • Tempo (T): Running done at anaerobic threshold; this is between about 5 and 7 percent faster than marathon pace for most runners.
  • Medium-long run (MLR): A run of 10 to 14 miles, depending on ability and experience. In this scheme, tempo running is embedded into these.
  • Long run (LR): Any run of 15 miles or longer.
  • Fast finish (FF): From 1.5 to 3 miles (or 10 to 20 minutes based on your current fitness) of running at the end of a MLR or LR, progressing from about 10K pace down to about 5K pace in a MLR and from about T pace to about 10K pace in a LR.
  • Short speed (SS): Reps of 200 to 400 meters (about 30 seconds to two minutes) at about 3K (two-mile) race pace.
  • Medium speed (MS): Reps of 600 to 1000 meters (about two to five minutes) at 3K to 5K race pace.
  • Long speed (LS): Reps of 1200 to 2000 meters (about five to seven minutes) at 5K race pace.
  • Marathon pace (MP): Your realistic goal race pace, held continuously for about 8 to 18 miles.

Note that tempo and MP are spaced as far apart as possible, ten or eleven days. Medium-long and long runs of the “fast-finish” variety are also maximally spaced apart.

Also, each week’s three key elements – the medium-long run, the speed session and the long run — are scheduled for the same day each week. Four of the six longer runs include specific, higher-end (i.e., MP or faster) pace assignments.

Walk-Through Example

A runner aiming for a 3:30 marathon (about 8:00 per mile) would have a 5K pace of about 7:00, a 10K pace of about 7:20, and a tempo pace of close to 7:30. Most tempo runs would be 3 to 6 miles, at the end of or within a MLR. Her everyday runs, including the unstructured MLR and LR, would be done at around 9:00 per mile, but this is less important.

The FF running, would, after a long or medium run at a conversational pace, start at about 7:20 pace and proceed down to about 7:00 pace. Track reps would be done at around 6:45 to 7:00 pace — that is, at about two-mile to 5K race pace.

The touchstone of the cycle, the marathon-pace run, peaks at a length of 15 to 18 miles, depending on your goals and experience. It’s helpful to be able to do these as races, provided you stick to the pace assignment.

How Many Cycles?

Assuming you have a base of six plus uninterrupted months of mileage that’s reasonably close to the volume of your previous marathon build-ups, you’re ready to transition into the program. That is, if your typical marathon training has included 60 miles a week and you’ve been at least three-fourths of that (40–50 miles) for six months of longer, you’re prepared to begin.

You should do at least three and at most five dedicated 21-day cycles, followed by a two- to three-week taper. Any more than that, and a risk of staleness or outright injury increases substantially. The last MP long run should fall three weeks before the big day.

To create a series of workouts that fit seamlessly into this scheme, you should err on the side of slightly conservative pacing, especially for the shorter sessions. No one workout is especially taxing, but if you can manage the juggling act, you should be more ready to roll than ever — especially in the final third of the race — when the gun goes off.