Four hours is the barrier that turns a marathon finisher into a confident racer. Holding 5:41 per kilometre for 42.2 km is not about raw speed — it demands aerobic base, a smarter pacing strategy than most first-timers use, and a disciplined fueling plan to survive the back half. This free 16-week plan builds from a 5K running base, peaks at 32 km long runs, and delivers every structured session directly to your Garmin watch with precise pace targets baked in.
Breaking four hours is within reach for any runner who can currently complete a 5K under 30 minutes and has the time to train consistently for 16 weeks. The physiology is straightforward: you need an aerobic base strong enough to hold 5:41/km for roughly four hours without your cardiovascular system giving out, and enough glycogen management to prevent the bonk that derails so many first-marathon attempts between kilometres 32 and 42.
Useful entry benchmarks before starting week 1:
If your 5K is under 25:00 and you are chasing sub-4 as a conservative first-marathon goal, the plan will work — your aerobic ceiling is higher than required and the volume will feel manageable. Use the VDOT calculator to find your current training paces before week 1.
This plan uses Daniels-derived paces calibrated to VDOT 37, the fitness level that puts a 4:00 marathon within reach on race day. If your VDOT sits between 35 and 39, these zones are your starting point — the engine adjusts them automatically if your fitness shifts during the plan:
| Zone | Pace (per km) | Pace (per mile) | Primary use |
|---|---|---|---|
| Easy (E) | 6:36 - 7:00 | 10:37 - 11:16 | Long runs, recovery, base days |
| Marathon (M) | 5:41 | 9:09 | Marathon-pace blocks in long run |
| Threshold (T) | 5:14 | 8:26 | Tempo runs, cruise intervals |
| Interval (I) | 4:55 | 7:55 | VO2max sessions (used sparingly) |
| Repetition (R) | 4:38 | 7:28 | Short economy strides |
The most important pace to internalize is Easy. Most first-marathon runners arrive at race day undertrained because they ran every easy run 30-45 seconds per kilometre too fast — accumulating fatigue rather than aerobic adaptation. If you cannot hold a conversation during an easy run, you are running too hard.
35-45 km/week. The long run grows from 16 to 22 km, all at easy pace with zero pace pressure. Tuesday features a 35-40 minute moderate run — faster than easy, but not threshold effort. The goal in this phase is load tolerance: tendons, joints, and connective tissue adapt more slowly than the cardiovascular system, so ramping too fast before they are ready is the primary injury mechanism in first-marathon training. Two down-weeks (weeks 2 and 4) hold volume at 80% to let adaptation consolidate.
45-55 km/week. Tuesday becomes a structured session: alternating 30-35 minute tempo runs at threshold pace (5:14/km) and cruise-interval sets (4-5 x 1.2 km at T-pace with 90s jog recovery). The long run extends to 26-28 km. Marathon-pace blocks appear for the first time in week 8: the final 4-6 km of one long run at 5:41/km. This is the session most runners find revelatory — 5:41 feels almost too easy at kilometre 22, and that feeling is exactly what race day needs to replicate at kilometre 38.
55-65 km/week. The long run peaks at 32 km with a 6-8 km marathon-pace block embedded in the final third. Tuesday escalates to a mixed session: 20 minutes at threshold pace followed by 2-3 x 800m at interval pace with full recovery. This combination targets the aerobic ceiling while reinforcing speed reserve. A down-week at week 11 holds volume to 45 km before the final peak in weeks 12-13.
Week 14 drops to 45 km: one threshold session, long run of 26 km. Week 15 drops to 30 km: one 6 km at marathon pace, long run of 18 km easy. Week 16 is race week — 20 km total across Monday through Thursday, including 4 x 100m strides on Tuesday and a 15-minute shakeout on Thursday. The fitness is locked in by week 13. The taper's job is to shed fatigue while keeping the neuromuscular system sharp. Do not add sessions during this window.
Data from training-load studies consistently shows that runners who exceed their easy-pace ceiling on base days arrive at quality sessions under-recovered and are forced to cut intervals short. For a sub-4 athlete at VDOT 37, easy pace is 6:36-7:00/km. That is almost certainly slower than your intuition says it should be — and that gap is where most first-marathon plans fail.
The aerobic adaptations that matter most for marathon performance — mitochondrial density, capillary growth in slow-twitch muscle fibres, fat oxidation efficiency — happen at easy pace intensities over many weeks. Running those sessions at 6:10/km instead of 6:45/km does not accelerate those adaptations; it just raises cortisol, disrupts sleep quality, and bleeds recovery capacity from your one or two weekly quality sessions.
Get-Split displays easy-pace bands as a green zone on your Garmin: if the pace alert fires, you are running too fast. Trust it, especially in the first six weeks when base-phase running feels effortless.
A 74 kg runner at marathon effort burns roughly 800-900 kcal per hour. The body stores approximately 2000 kcal of glycogen — enough for about 2 hours 15 minutes to 2 hours 30 minutes at sub-4 pace. Without exogenous carbohydrate, most runners hit the wall between kilometres 30 and 35. With it, the wall is optional.
The protocol that works:
Fueling is a trainable skill, not a race-day gamble. Runners who discover mid-race that their chosen gel causes nausea are runners who did not test it in training. The plan flags your week-11 and week-13 long runs as mandatory fueling rehearsals.
Enter your most recent race time — 5K, 10K, or half marathon — and your target race date. The engine calculates your current VDOT, confirms whether sub-4 is realistic in the time available, and builds a complete 16-week schedule:
The full plan, all training paces, and the Garmin push integration are free. No subscription required to generate and start training.
You should be able to run 30-40 minutes continuously at an easy conversational pace before starting week 1. A recent 5K time under 31:00 is a useful benchmark. If you are still run-walking, spend 4-6 weeks building to a continuous 35-minute easy run before committing to the 16-week schedule — starting injured from overload in week 3 helps no one.
Four running days per week: Tuesday moderate or threshold, Thursday easy, Saturday easy or medium-long, Sunday long run. An optional easy cross-train (cycling, swimming, walking) on Wednesday maintains aerobic stimulus without run-specific load. Monday and Friday are rest days. A 3-day variant drops Thursday and is viable for runners with tighter schedules — just accept the long run will do more work in isolation.
The peak long run is 32 km, completed in weeks 12-13. Decades of marathon coaching — and the physiology of glycogen depletion and musculoskeletal stress — shows that runs beyond 32-35 km in training create injury and recovery cost that outweighs the marginal fitness benefit. You do not need to run the full marathon distance in training to finish it confidently.
Yes. A planned run-walk strategy from kilometre 25 onward can cost 3-4 minutes total while preventing the full glycogen bonk that costs 20-30 minutes. Many runners targeting sub-4 walk 30-60 seconds at water stations from kilometre 27 onward — taking on fluid and gel without slowing their running form. The plan includes guidance on triggering the walk strategy based on heart-rate drift, not just fatigue feeling.
Miss one week: skip it, return to the schedule at the next week, and accept the fitness cost is trivial (roughly 1-2% aerobic drop). Miss two consecutive weeks due to illness: back up two weeks in the schedule and restart from there. Miss more than three weeks due to injury: reassess the target race date — racing a marathon on depleted training is a recipe for a painful and demoralizing experience that puts people off the distance for years.
Connect Garmin in the settings page and every structured session — threshold tempo runs, marathon-pace long-run blocks, interval reps — appears on your Garmin device with step-by-step instructions and pace target alerts. Easy runs show as duration targets. The plan releases month by month so your calendar stays clean rather than showing all 16 weeks of sessions simultaneously.