Half Marathon 12-Week Training Plan: Weekly Mileage and Intensity Distribution

Introduction

The half marathon (21.0975 km) is an important stepping stone for many runners progressing from 10K to the full marathon. Compared to the full marathon, the half marathon offers enough of a challenge without requiring an excessively large training volume. However, jumping in without a plan can lead to disappointing results at best and injury at worst. This article provides a complete 12-week training blueprint, from base building to pre-race tapering, suitable for runners aiming to finish or break the 2-hour mark.

12-Week Plan Overview

The 12 weeks can be divided into three phases: Base Phase (Weeks 1–4), Build Phase (Weeks 5–9), and Race Phase (Weeks 10–12). The core principle is the “10% rule”—weekly mileage increases should not exceed 10% of the previous week’s total, reducing the risk of overuse injuries.

Key Training Elements Explained

Long Run

The long run is the cornerstone of half marathon preparation. It is recommended to do it on weekend mornings when it is cooler, at a pace 60–90 seconds per kilometer slower than your goal race pace. In Taiwan, the Keelung River, Dahan River, and Tamsui River riverside parks are ideal long-run routes, with flat terrain and ample water stations.

• Run the entire long run at a “conversational” intensity
• Try to pick up the pace to goal race pace for the final 3–5 km
• The late-run acceleration helps simulate the fatigue experienced in the final stages of a race

Tempo Run

Schedule one 20–40 minute tempo run each week, maintaining an intensity that is “slightly uncomfortable but sustainable,” corresponding to roughly 85–90% of maximum heart rate.

Interval Training

Starting from Week 7, introduce 1000m repeats with 2 minutes of easy jogging recovery between sets. Six sets of 1000m is a classic workout for half marathoners, effectively improving VO2max and running economy.

Typical Weekly Training Schedule

Using Week 6 (weekly mileage 44–50 km) as an example:

• Monday: Complete rest or light stretching
• Tuesday: Easy aerobic run 10–12 km
• Wednesday: Tempo run 6–8 km (including warm-up and cool-down)
• Thursday: Easy recovery run 8–10 km
• Friday: Rest or strength training
• Saturday: Long run 18 km
• Sunday: Easy recovery run 6–8 km

Practical Tips

• A training log is essential: record distance, pace, heart rate, and perceived fatigue (1–10 scale) for each session to track progress and adjust the plan
• Sleep is the best recovery tool: 7–9 hours of sleep per night is crucial for muscle repair
• Don’t skip taper weeks: the reduced mileage in Weeks 4, 8, 11, and 12 is not a step backward but allows the body to supercompensate
• Track shoe mileage: a half marathon training cycle covers roughly 400–600 km; if your primary shoes have exceeded 600 km, consider getting new ones

Conclusion

The essence of the 12-week plan lies in “progressive overload” and “timely recovery.” Every runner has a different fitness base and recovery capacity—the plan is just a framework. If you feel particularly fatigued, feel free to cut volume by 20–30%. When you stand at the starting line of any half marathon in Taiwan, having completed the full 12 weeks according to the plan, finishing or hitting your goal will come naturally.

Related Reading

• Beginner Half Marathon 12-Week Training Plan: From 5km to Finishing 21km
• Half Marathon Training Plan: 8-Week Preparation Program
• Marathon Training Plans Fully Explained: The Advanced Path from Half to Full Marathon
• First Marathon Preparation Plan: 12 Weeks from 10K to Full Marathon