12-week half marathon training plan

This plan is for runners who already have a minimal base. It combines progressive volume, training variety and recovery periods to take you gradually from your current runs to a long run of 18 to 19 km. We go step by step, without rushing things, because consistency always beats poorly measured intensity.

Prerequisites before you start

Before starting a 12-week plan, you should already be able to run between 5 and 8 km continuously, without walking, at a comfortable pace. This base means your muscles, tendons and cardiovascular system have already started adapting to the impact of running. If you're not there yet, take another four to six weeks to build that foundation before diving in.

Ideally, you've already been running two or three times a week for at least a month or two. A half-marathon plan is not the time to discover running. It's the time to channel an existing habit toward a specific goal.

• Be able to run 5 to 8 km without stopping
• Have been running regularly for at least 4 to 8 weeks
• No active injury still healing
• A pair of shoes suited to your stride (visit specialty stores for a gait analysis)
• Medical clearance if you're over 40 or have a health history

The plan's three-phase structure

The 12 weeks are divided into three distinct blocks, each with a specific goal. This periodization lets your body adapt gradually while reducing the risk of injury or overtraining.

Phase 1: the base (weeks 1 to 4)

The goal here is to gently increase weekly volume and get your body used to running more often. The focus is on easy endurance running, that slow pace at which you can hold a conversation. The long run gradually climbs from 8 to 12 km. Very little intensity is introduced; the priority is mileage accumulated comfortably.

Phase 2: development (weeks 5 to 9)

This is the heart of the plan. Volume peaks and quality work is added: threshold sessions and intervals. The long run tops out at around 18 to 19 km in week 9. This is the most demanding phase, the one where your body learns to sustain prolonged effort and handle a steady pace.

Phase 3: the taper (weeks 10 to 12)

Volume is gradually reduced to let your body absorb all the work done and arrive fresh on race day. You keep a bit of intensity to stay sharp, but total mileage drops significantly. Many runners dread this phase because they're afraid of losing fitness. Rest assured: the gains are already banked, and the taper simply reveals them.

The four types of runs to master

A good plan isn't just about running the same way every time. Four types of sessions each work a different aspect of your fitness.

• Easy endurance running: the runner's bread and butter. A slow, comfortable pace where you breathe easily. This is what develops your aerobic system and your resistance to fatigue. Most of your kilometres are run here.
• The long run: once a week, usually on the weekend. It gets your body and mind used to prolonged effort and climbs to 18 or 19 km. Run it slowly, slower than your goal race pace.
• Threshold or tempo: a sustained but controlled effort, at a pace you could hold for about an hour in a race. This session pushes back your threshold, the point where lactic acid builds up. It enables you to hold a demanding pace for longer.
• Intervals: fast repetitions separated by recovery, for example 6 × 400 m or 5 × 800 m. These sessions improve your power, your running economy and your maximal aerobic speed.

Progressive volume: 3 to 4 runs per week

The plan is built on three to four runs per week. Three is the minimum to progress without overloading your schedule; four is ideal for most recreational runners. Beyond that, you get into a volume that requires more experience and recovery time.

The golden rule: don't increase total volume by more than 10% from one week to the next. Also plan a recovery week (reduced volume) every three or four weeks to let your body assimilate the work. Here is the week-by-week progression, in approximate total mileage.

• Week 1: about 20 km total, 8 km long run
• Week 2: about 23 km, 9 km long run
• Week 3: about 26 km, 11 km long run
• Week 4: recovery, about 20 km, 10 km long run
• Week 5: about 28 km, 13 km long run, first tempo
• Week 6: about 31 km, 14 km long run
• Week 7: about 34 km, 16 km long run
• Week 8: recovery, about 26 km, 13 km long run
• Week 9: about 37 km, 18 to 19 km long run (peak)
• Week 10: taper, about 30 km, 15 km long run
• Week 11: taper, about 24 km, 11 km long run
• Week 12: about 15 km of light training, then the race

A detailed sample week

Here's what a typical week in the development phase looks like, with four runs. Adjust the days to your schedule, but always keep at least one rest day between two hard sessions.

• Monday: complete rest or light activity (walking, cycling, swimming)
• Tuesday: intervals, for example a 15 min warm-up, 6 × 800 m with 90 sec recovery, 10 min cool-down
• Wednesday: 6 to 8 km easy endurance run at a slow pace
• Thursday: rest or strength training (core, legs)
• Friday: threshold or tempo, for example 15 min easy, 20 min at a sustained pace, 10 min easy
• Saturday: rest
• Sunday: long run at easy endurance pace (12 to 18 km depending on the week)

Note the importance of rest days. It's during recovery that your body gets stronger, not during the effort itself. Skipping rest days is one of the most common mistakes among motivated runners.

Managing your target pace

Running all your runs at the same pace is counterproductive. Each type of session has its own pace, and respecting them makes all the difference. The most common trap is running easy runs too fast and fast runs not fast enough.

To determine your paces, rely on a recent race or a test. Our pace calculator helps you convert your time over a known distance into precise training paces: endurance pace, threshold pace, interval pace and goal race pace for your half marathon. This tool becomes your reference so you're not running blind.

Your goal race pace should be a little slower than your threshold pace. The simple rule: if you can barely get a few words out during your easy runs, you're going too fast. Easy endurance running should remain truly comfortable.

The final taper

In the last two weeks, you reduce volume by 30 to 50% while keeping a bit of intensity. This reduction lets your glycogen stores rebuild, muscle micro-tears heal and accumulated fatigue dissipate. You may feel a bit heavy or restless; that's normal.

• Reduce your mileage, not the frequency of your runs
• Keep a few short strides to stay sharp
• Sleep more during this period
• Don't try anything new: no new shoes, food or gear
• Resist the urge to do one last big long run

Race-day nutrition and hydration

Energy management can make or break your race. The half marathon lasts long enough for nutrition to matter, without requiring the complex logistics of a marathon.

• The day before: a carbohydrate-rich meal, but nothing unusual or too heavy. Stay well hydrated throughout the day.
• In the morning: a light, easily digestible breakfast 2 to 3 hours before the start, for example toast with peanut butter and a banana. Avoid excess fibre and fatty foods.
• During: an energy gel or equivalent around km 10 or 12 can help you hold your pace in the second half. Take small sips at the water stations rather than gulping it all at once.
• Absolute rule: never try a new food or a new gel on race day. Everything you consume should have been tested during your long training runs.

Mistakes to avoid

• Starting too fast: the number one mistake. The adrenaline of the start pushes you to get carried away, and you pay dearly for it in the last kilometres. Stick to your target pace from the very first km.
• Neglecting rest days: more isn't always better. Recovery is part of training.
• Running every run at the same pace: neither slow enough nor fast enough. Variety is essential.
• Ignoring pain signals: temporary discomfort is normal; persistent pain is not. Better to skip a session than miss the race.
• Skipping the taper: trying to do too much in the final weeks ruins months of preparation.
• Neglecting strength training: a strong core and legs prevent many injuries.

Adapting to québec's climate

Training in Québec means dealing with changing conditions. Depending on the season of your half marathon, your preparation may span the spring thaw, the humid summer heat or the autumn cold.

• In hot, humid weather: run early in the morning or in the evening, hydrate more and accept that your pace will slow down. Don't chase a time in 30-degree heat.
• In cold weather: dress in layers, protect your extremities and warm up indoors before heading out. Your body works harder in the cold.
• Icy or snowy sidewalks: removable traction cleats make winter runs safe. Otherwise, the treadmill remains a valid option for maintaining volume.
• Wind: plan your routes to finish with the wind at your back when possible, and don't be afraid to run out-and-backs.

The key is flexibility. A plan is a guide, not a law. If a storm hits on the day of a key session, push it back a day rather than running in dangerous conditions. Consistency over 12 weeks matters far more than a single perfect session.

Conclusion

A successful half marathon isn't a matter of talent, but of methodical preparation. By following the 12-week progression, varying your runs, managing your paces with the pace calculator and taking care of your recovery, you'll reach the start line ready to give it your all. Trust the process, listen to your body and savour every step of the journey. Now all that's left is to choose your goal: check out the Québec race calendar to find the half marathon that excites you, and start your 12-week countdown today.