A 16-week marathon training plan built around TSS and CTL

A good marathon training plan is not a fixed calendar — it is a structure that adapts to how you respond. This 16-week plan is built around TSS and CTL, so the load stays in the right zone whether you are crushing the workouts or struggling through them.

Before you start

• You should be running 25–30 km/week consistently for at least 3 months before starting this plan.
• You need a recent threshold pace (5K race or time trial in the last 8 weeks).
• You need to be healthy and uninjured. If not, start the plan a few weeks later — there is no medal for starting on day one.

The three phases

• Weeks 1–6: Build. Establish aerobic base and weekly mileage. Long run builds from 18 km to 28 km.
• Weeks 7–12: Specific. Add marathon-pace work and a longer long run (up to 32 km). Race-specific fitness climbs fastest here.
• Weeks 13–16: Sharpen + taper. Race-pace sharpening, then a 2-week taper to arrive fresh.

Weekly load targets (TSS)

These are guidelines. Real life intervenes; adapt using the rules below.

• Build phase: weekly TSS 350 → 550. Three hard sessions, two easy, one long run, one rest day.
• Specific phase: weekly TSS 500 → 700. Add marathon-pace work and one longer long run. Stay below ~750 TSS/week.
• Sharpen (weeks 13–14): weekly TSS 400 → 500. Race-pace sharpness, lower volume.
• Taper (weeks 15–16): weekly TSS 300 → 250 → 150. Maintain intensity, slash volume.

What each week looks like

A typical specific-phase week:

• Monday: rest or 30 min easy (TSS 30)
• Tuesday: intervals — 5 × 1 km at 5K pace (TSS ~80)
• Wednesday: 8 km easy (TSS 50)
• Thursday: tempo — 12 km with 8 km at marathon pace (TSS ~95)
• Friday: rest or 30 min easy (TSS 30)
• Saturday: easy 8–10 km (TSS 60)
• Sunday: long run 22–28 km with last 8 km at marathon pace (TSS 180)

Weekly total: ~525 TSS. Read the underlying math in our TSS guide.

The rules that matter

• CTL rises about 3–5 per week. If yours stalls for 2+ weeks, you are not absorbing the load — add an easy day or shorten the long run.
• ATL should peak 7–10 days before the race. If ATL is still climbing into race week, you undertapered. If it crashed early, you tapered too long.
• TSB on race morning should be +5 to +20. Negative means you are carrying fatigue into the start — you will feel heavy for the first 10K. How to taper properly.
• If you miss a week, do not double up. Resume the plan where it makes sense — usually one phase back, not the missed week.

Why a TSS-based plan beats a fixed calendar

A traditional plan says “week 8: 22 km long run”. A TSS plan says “you should have built to about 32 km long run, ~180 TSS, with CTL around 60 by now”. The first fails the moment you get sick, travel, or have a bad patch. The second adapts: you can swap the long run for two back-to-back moderate runs, or shift the schedule around the rest of your week, and still end up in the right place on race day.

Track it automatically

TrainCurve scores every run as TSS (via pace or HR — see our hrTSS/rTSS guide), rolls it into your CTL, ATL and TSB, and tells you when to push, hold, or back off. Start free and build a marathon plan that adapts to you.