20-Week Clarence DeMar Marathon Training Plan

Keene, NHSeptember 26, 2027

Start around May 9, 2027. The calendar below gives each phase a real date, then the course guidance shows where to make the build specific to Clarence DeMar Marathon.

The Clarence DeMar Marathon starts at 7:00 a.m. in Gilsum, New Hampshire, a village of a few hundred people, and finishes 429 feet lower on Appian Way at Keene State College. In between it runs past Surry Mountain Dam and Bretwood Golf Course, and it spends miles 22 to 24 inside the Greenlawn and Woodland cemeteries, where the road climbs.

Race day
September 26, 2027
Start window
May 9, 2027
Runway
20 weeks
Course
Downhill · Point to Point
Plan choice
Current training

Does this window fit your starting point?

Use the longer window to make the early build calmer, not to add five months of hard training. The plan should begin close to your current load, hold most running easy, and delay the biggest race-specific work until the middle of the cycle.

  • You want a longer foundation phase before marathon-specific training.
  • Your current mileage is steady but below the load you expect to carry later.
  • You prefer gradual long-run growth with regular step-back weeks.
  • You can sustain a five-month routine without turning every week into a peak week.

The 20-week Clarence DeMar Marathon calendar

These dates define the job of each phase. Your current mileage, recent longest run, experience, goal, and available days still decide the actual workouts inside them.

Foundation

Weeks 1–6

May 10, 2027–Jun 20, 2027

Set the routine, grow easy volume gradually, and finish each week with enough control to repeat it.

Build

Weeks 7–13

Jun 21, 2027–Aug 8, 2027

Extend the long run, introduce race-specific terrain, and keep recovery weeks on the calendar.

Peak

Weeks 14–17

Aug 9, 2027–Sep 5, 2027

Complete the most demanding race rehearsals and settle fueling, pacing, shoes, and clothing before taper begins.

Taper

Weeks 18–20

Sep 6, 2027–Sep 26, 2027

Reduce the load, keep familiar running in the week, and let the work from the previous four months show up on race day.

Make the window specific to Clarence DeMar Marathon.

Build general durability first. Add the race's hills, flat sustained running, downhill exposure, heat, or humidity in layers after the weekly rhythm is stable, then make the final long runs the most course-specific.

Read the full race guide

How to train for the Clarence DeMar Marathon

Train for the Clarence DeMar Marathon as a downhill race with an uphill finish, which is an unusual combination and the reason a generic plan fails here. You need quads that can absorb about 1,100 feet of cumulative descent and still produce force on climbs at miles 22 and 24, when most runners have nothing left to give.

Start downhill work early, at least eight weeks out, and build it slowly. Descents cause eccentric muscle damage and the adaptation to it is slow, but it's real. Run repeats on a moderate grade at goal effort with a short quick stride and no heel braking. Then, and this is the part almost everyone skips, put a climb at the end of your long run.

A good session for this course looks like two hours of rolling running, a sustained descent through the middle, and two short hard hills inside the last twenty minutes. That's race day compressed into one workout. If you can hold your form on those closing hills, the cemeteries at mile 22 will feel like something you already rehearsed.

Clarence DeMar Marathon course facts

Course
Point to Point · Downhill · Road/Pavement
Elevation gain / loss
706 ft gain, 1,135 ft loss
Highest / lowest point
928 ft / 495 ft
Marathon finishers
308 in 2025 (small field)
Boston qualifier
Certified Boston qualifying course
Finishers running a qualifying time
14.3% in 2025
Typical race morning
51°F at the start, 88% humidity, clear
Race day high / low
68°F / 42°F on average

Sources

Let your current training decide the actual plan.

Current mileage, recent longest run, marathon experience, goal, and available days determine which plans rank first. After you choose and subscribe, Stride dates every workout through September 26, 2027.

Build My Plan

20-week Clarence DeMar Marathon plan questions, answered.

When should I start a 20-week Clarence DeMar Marathon plan?

The 2027 Clarence DeMar Marathon is scheduled for September 26, 2027, so the 20-week window opens around May 9, 2027. Treat that as the outside edge of the window, then line week one up with the plan's normal weekly rhythm.

Is a 20-week plan long enough for the Clarence DeMar Marathon?

Use the longer window to make the early build calmer, not to add five months of hard training. The plan should begin close to your current load, hold most running easy, and delay the biggest race-specific work until the middle of the cycle. The course does not change the opening load you can handle, so choose from your current mileage and recent longest run before adding race-specific terrain.

How should I prepare for the Clarence DeMar Marathon course in 20 weeks?

Build general durability first. Add the race's hills, flat sustained running, downhill exposure, heat, or humidity in layers after the weekly rhythm is stable, then make the final long runs the most course-specific. Train for the Clarence DeMar Marathon as a downhill race with an uphill finish, which is an unusual combination and the reason a generic plan fails here. You need quads that can absorb about 1,100 feet of cumulative descent and still produce force on climbs at miles 22 and 24, when most runners have nothing left to give.

What if the 20-week Clarence DeMar Marathon window has already started?

Do not double weeks or cram missed mileage into the remaining calendar. Use your current mileage, recent longest run, experience, goal, and available days to choose a plan that can enter at an appropriate point while preserving the taper.

Is the Clarence DeMar Marathon downhill?

Net downhill, yes, by about 429 feet from Gilsum to Keene. But it isn't a straight descent. The organizers describe mostly gentle rolling hills through the first half, a long climb at mile 15, and steeper climbs at miles 22 and 24, so the hardest running comes late rather than early.

Is the Clarence DeMar Marathon a good Boston qualifier?

Yes, one of the better small-race options. 14.3% of finishers ran a Boston qualifying time in 2025 and 11.3% in 2024, with rates near 20% in 2021 and 2022. The course is USATF certified and its net drop is not large enough to trigger the BAA's downhill adjustment.

Put the 20-week window against your actual race.

Each page counts back from race day, maps the 4 phases to real dates, and applies the window to that course and its typical conditions.