Foundation
Weeks 1–4
Jan 25, 2027–Feb 21, 2027
Establish repeatable weeks, keep most running easy, and begin extending the long run without forcing the pace.
16-Week Colfax Marathon Training Plan
Denver, COMay 16, 2027
Start around January 24, 2027. The calendar below gives each phase a real date, then the course guidance shows where to make the build specific to Colfax Marathon.
Every mile of the Colfax Marathon is run above 5,000 feet. The course sits between 5,172 and 5,533 feet as it works through Denver's City Park, Sloan's Lake and downtown, starting at 6:00 a.m. on the east side of Ferril Lake. The terrain is gentle. The air is the difficulty.
- Race day
- May 16, 2027
- Start window
- January 24, 2027
- Runway
- 16 weeks
- Course
- Rolling Hills · Mostly Loop
- Plan choice
- Current training
Does this window fit your starting point?
Use this window when you have a running base and want several weeks before the hardest marathon-specific work begins. The extra month over a 12-week plan creates more room for gradual long-run growth and recovery.
- You run consistently enough that week one is a continuation, not a restart.
- You want a distinct foundation phase before the biggest long runs.
- You can protect your planned run days for roughly four months.
- Your race date leaves the full window without forcing skipped weeks.
The 16-week Colfax 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.
Build
Weeks 5–10
Feb 22, 2027–Apr 4, 2027
Increase the weekly load, preserve step-back weeks, and introduce the terrain and effort the race will require.
Peak
Weeks 11–13
Apr 5, 2027–Apr 25, 2027
Complete the biggest race-specific weeks and use long runs to lock in fueling, pacing, and equipment.
Taper
Weeks 14–16
Apr 26, 2027–May 16, 2027
Bring volume down while keeping the weekly rhythm familiar. Training is finished before race week begins.
Make the window specific to Colfax Marathon.
Use the first month to establish consistency, then make long runs progressively more specific to the race's terrain and conditions. The course rehearsal should grow with the plan, not appear all at once in peak week.
Read the full race guideHow to train for the Colfax Marathon
Train for the Colfax Marathon by building aerobic ceiling and by setting an honest altitude-adjusted goal. If you live near sea level, the 693 feet of climbing is not your problem; running 26.2 miles in air a mile up is. Plan for a slower goal pace than your flat-course fitness says you have earned.
In practice that means more volume at easy effort and fewer sessions chasing exact paces. Threshold work run by feel travels to altitude much better than threshold work run by watch. If you can get to elevation at all in the final block, even for a weekend, take it.
Two logistics that are really training. A 6:00 a.m. start means eating at around 3:30 a.m., so rehearse that breakfast on long runs rather than improvising it. And dry Colorado air pulls fluid out of you without the soaked shirt that normally warns you, so drink on a schedule instead of by thirst.
Colfax Marathon course facts
- Course
- Mostly Loop · Rolling Hills · Road/Pavement
- Elevation gain / loss
- 693 ft gain, 694 ft loss
- Highest / lowest point
- 5,533 ft / 5,172 ft
- Marathon finishers
- 2,917 in 2026 (mid-size field)
- Boston qualifier
- Certified Boston qualifying course
- Finishers running a qualifying time
- 2.5% in 2026
- Typical race morning
- 46°F at the start, 73% humidity, partly cloudy
- Race day high / low
- 68°F / 40°F on average
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 May 16, 2027.
16-week Colfax Marathon plan questions, answered.
When should I start a 16-week Colfax Marathon plan?
The 2027 Colfax Marathon is scheduled for May 16, 2027, so the 16-week window opens around January 24, 2027. Treat that as the outside edge of the window, then line week one up with the plan's normal weekly rhythm.
Is a 16-week plan long enough for the Colfax Marathon?
Use this window when you have a running base and want several weeks before the hardest marathon-specific work begins. The extra month over a 12-week plan creates more room for gradual long-run growth and recovery. 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 Colfax Marathon course in 16 weeks?
Use the first month to establish consistency, then make long runs progressively more specific to the race's terrain and conditions. The course rehearsal should grow with the plan, not appear all at once in peak week. Train for the Colfax Marathon by building aerobic ceiling and by setting an honest altitude-adjusted goal. If you live near sea level, the 693 feet of climbing is not your problem; running 26.2 miles in air a mile up is. Plan for a slower goal pace than your flat-course fitness says you have earned.
What if the 16-week Colfax 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.
How does altitude affect the Colfax Marathon?
It is the defining factor. The Colfax Marathon runs entirely between 5,172 and 5,533 feet, and runners arriving from sea level should expect to run slower than their flat-course fitness suggests, especially after mile 18. There is no way to fix that inside a training block, so adjust the goal instead.
Is the Colfax Marathon a good Boston qualifier?
No. Only 2.5% of Colfax finishers ran Boston qualifying times in 2026, and 3.6% did in 2025. The course itself is gentle, with 693 feet of climbing across 26.2 miles, but the altitude takes back more than the profile gives. Choose a low-elevation race if a qualifier is the goal.
Put the 16-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.