Chasing 1:40 – A 12‑Week Half‑Marathon Training Journey
The goal
Target: half marathon in 1 hour 40 minutes (average pace ≈ 7:38 per mile / 4:45 per km).
Getting to 1:40 takes three things: enough speed to hold sub-8 miles for most of the race, enough endurance for 10 to 12 mile runs at manageable intensity, and the head to push through the fatigue that usually shows up around mile 10.
Pre-requisites
Before starting, check the baseline:
- Current half-marathon PB: 1:45 to 1:50 (or a 10K in 50 min or under).
- Weekly mileage: 15 to 25 miles (24 to 40 km) for the past 4 weeks.
- Injury-free: no lingering aches that worsen when you run.
If you’re slightly behind, plan on a 2-week build-up of steady running first.
How the plan works
| Workout | Purpose | Typical pace / effort |
|---|---|---|
| Easy run | Develop aerobic fitness, aid recovery | 60–70% max HR, ~1:30–1:45/mi slower than race pace |
| Tempo run | Train lactate threshold (pace you can hold for an hour) | 85–90% max HR, ~7:50–8:00/mi (slightly slower than race pace) |
| Interval (speed) | Increase VO₂ max and running economy | Hard effort, 90–95% max HR. 5K–10K race pace or faster for short reps |
| Long run | Build endurance, train fuel metabolism | Easy to moderate, 60–75% max HR. Finish last 2 to 3 mi at goal race pace |
| Recovery / cross-train | Maintain training while lowering joint stress | Light activity (cycling, swimming, yoga), 30 to 45 min |
| Rest | Full day for muscular repair and glycogen replenishment | — |
Pace numbers are reference points. Heart-rate zones or perceived effort work fine without a watch.
Weekly plan (12 weeks)
| Week | Mon | Tue | Wed | Thu | Fri | Sat | Sun |
|---|---|---|---|---|---|---|---|
| 1 | Rest | Easy 4 mi (9:00) | Tempo 3 mi @ 7:55 | Easy 4 mi | Rest or cross-train | Long 7 mi (9:15) | Easy 3 mi |
| 2 | Rest | Easy 4 mi | Interval 5×400 m @ 5K pace, jog 400 m | Easy 4 mi | Rest or cross-train | Long 8 mi (9:10) | Easy 3 mi |
| 3 | Rest | Easy 5 mi | Tempo 4 mi @ 7:50 | Easy 5 mi | Rest or cross-train | Long 9 mi (9:05) | Easy 3 mi |
| 4 | Rest | Easy 5 mi | Interval 4×800 m @ 5K–10K pace, jog 400 m | Easy 5 mi | Rest or cross-train | Long 10 mi (9:00) | Easy 4 mi |
| 5 | Rest | Easy 5 mi | Tempo 5 mi @ 7:45 | Easy 5 mi | Rest or cross-train | Long 11 mi (8:55) | Easy 4 mi |
| 6 | Rest | Easy 5 mi | Interval 6×400 m fast, jog 400 m | Easy 5 mi | Rest or cross-train | Long 12 mi (8:50) | Easy 4 mi |
| 7 | Rest | Easy 6 mi | Tempo 5 mi @ 7:40 | Easy 6 mi | Rest or cross-train | Long 13 mi (8:45) | Easy 4 mi |
| 8 | Rest | Easy 6 mi | Interval 5×800 m fast, jog 400 m | Easy 6 mi | Rest or cross-train | Long 14 mi (8:40) | Easy 4 mi |
| 9 | Rest | Easy 6 mi | Tempo 6 mi @ 7:38 | Easy 6 mi | Rest or cross-train | Long 12 mi (goal-pace finish) | Easy 3 mi |
| 10 | Rest | Easy 5 mi | Interval 4×1200 m @ 10K pace, jog 400 m | Easy 5 mi | Rest or cross-train | Long 10 mi (steady) | Easy 3 mi |
| 11 | Rest | Easy 5 mi | Tempo 5 mi @ 7:40 | Easy 5 mi | Rest or cross-train | Long 8 mi (last 2 mi @ 7:38) | Easy 3 mi |
| 12 (race week) | Rest | Easy 4 mi | Rest | Easy 3 mi (optional strides) | Rest | Race day, half marathon 1:40 | Rest |
Distances are in miles. Multiply by 1.609 for kilometers.
Detailed workout descriptions
Easy run
- Start with 5 to 10 min of easy jogging.
- Settle into a pace where full sentences flow naturally.
- Close with 5 min of easy jogging and static stretches.
Tempo run
- 10 min at an easy pace.
- Hold tempo pace for 20 to 30 min (a notch below goal race pace). If steady pacing is hard, aim for “comfortably hard”: speaking comes in short bursts.
- Cool down 10 min easy.
Interval (speed) session
- Warm up 10 to 15 min easy plus 4 to 5 strides.
- Run the repeats at target interval pace (e.g. 5K pace for 400 m reps). Keep effort even rep to rep.
- Recover with a jog or walk for the listed time (usually equal to work duration).
- Cool down 10 min easy.
Long run
- Start aerobic and conversational.
- Shift to a steady effort in the second half.
- In weeks 9 to 11, run the final 2 to 3 mi at goal race pace to practice holding speed when tired.
- Cool down and stretch thoroughly.
Recovery / cross-train
Low-impact work, swimming, cycling, or elliptical, for 30 to 45 min. Keep it easy. This is restoration, not a second hard session.
Notes and tips
- Building mileage: no more than 10% weekly increase to prevent injury.
- Body awareness: if soreness lingers, swap a hard workout for an easy run or take a day off.
- Nutrition: test race-day fuel on long runs (gels, sports drinks, or solid food). Aim for 30 to 60 g carbs per hour.
- Fluids: know your sweat rate. Aim for fluid loss under about 2% of body weight.
- Strength: two 20 to 30 minute sessions a week (core, glutes, posterior chain).
- Without a watch: heart-rate zones and perceived exertion work fine.
- Visualization: picture yourself running the hard miles (10 and 11). Self-talk can save real seconds.
FAQ
Q: I missed a key workout. What should I do? A: Replace it with an easy run and continue the rest of the week normally. Avoid back-to-back hard sessions.
Q: My assigned paces feel wrong after a few weeks. A: Run a recent time trial (5K works well) to recalibrate. Shift training paces by the same percentage.
Q: Is it okay to replace a run with a bike session? A: Yes, on cross-train days. Keep effort light to moderate. Don’t substitute for quality speed or tempo work.
Q: I have a history of shin splints. What precautions help? A: More grass or trail running, lower-leg strengthening, and don’t ramp mileage too fast.
Q: What if race day is much warmer than training? A: Do at least one long effort in heat, or simulate it with extra layers. Adjust the fluid plan to match.
Closing and suggested workout
A 1:40 half is within reach if you stay consistent and progress sensibly. Every mile builds the engine and the confidence.
To kick off the program, try the week 1 tempo:
- Warm up 10 min easy.
- Hold 7:55 min/mi for 3 mi (right below goal pace).
- Cool down 10 min easy.
Notice your breathing, track how your legs feel, and recognize you’re laying the groundwork for 1:40.
References
- 1/2 Marathon 12 Week Beginner | running Training Plan | TrainingPeaks (Blog)
- 1/2 Marathon 16 Week Beginner | running Training Plan | TrainingPeaks (Blog)
Collection - 12‑Week Half‑Marathon Build
Easy Run – 4 mi
View workout details
- 10min @ 6'00''/km
- 0.0mi @ 9'00''/mi
- 5min @ 6'00''/km
Tempo Run – 3 mi
View workout details
- 10min @ 6'00''/km
- 0.0mi @ 7'55''/mi
- 10min @ 6'00''/km
Long Run – 7 mi
View workout details
- 10min @ 5'45''/km
- 0.0mi @ 5'45''/km
- 0.0mi @ 4'45''/km
- 10min @ 5'45''/km
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