20-week marathon training plan

This practical program guides you week by week, from day one to the starting line. It’s structured into four five-week blocks: foundation, development, specific training, and tapering. Each block has a clear objective, a target volume, and specific workouts. Tailored to Québec’s climate and its unpredictable seasons, it will get you to the 42.195 km finish line in good health. For an overview of the principles, check out our marathon training guide.

Before you begin: prerequisites

This program assumes you have a solid foundation. You should already have been running three to four times a week for several months and be able to handle a weekly mileage of about 30 km. Ideally, you’ve already completed a 10 km race or a half-marathon. Without this foundation, take a few months first to build your endurance before starting your training.

• Three to four runs per week without persistent pain.
• A pair of running shoes suited to your stride, replaced every 600–800 km.
• Medical clearance if you’re over 40 or have a history of cardiovascular issues.
• Patience: 20 weeks—stick with it from start to finish.

The four types of workouts

Throughout the program, you’ll alternate between four types of workouts. Understanding their roles will help you maintain the right paces. A pace calculator lets you set your target speeds based on your goal time.

• Basic endurance: a slow, comfortable pace where you can hold a conversation. This makes up the bulk of your training volume—about 70% of your total kilometres.
• Threshold (tempo): Sustained but controlled effort—the pace you could maintain for about an hour. Develops the ability to run fast for a long time.
• Interval training (VMA): Short, fast repetitions interspersed with recovery periods. Improves aerobic power and running efficiency.
• Recovery: Very slow jogging or complete rest. It is during rest that the body gets stronger—never the other way around.

Block 1: Foundation (weeks 1–5)

The goal of this first block is simple: to build basic endurance and get your body used to running regularly. The focus isn’t on speed; instead, you’ll rack up kilometres at a moderate intensity. Tendons, ligaments, and muscles gradually strengthen, which helps prevent injuries later on.

• Weekly mileage: 40 to 50 km.
• Long run: gradually increase from 16 to 22 km, maintaining a comfortable breathing rhythm.
• Key sessions: two to three endurance runs, one light threshold session (2 x 10 min), and one long run on the weekend.

Week 4 is a recovery week: reduce your mileage by about 25% to allow your body to adapt. This pattern of three to four weeks followed by a lighter week repeats throughout the program. Listen to your body: unusual fatigue is a warning sign, not a sign of weakness.

Block 2: Development (weeks 6–10)

Your body is now adapted to the base volume. We increase the workload and introduce more structured, high-quality training. This is where the long run begins to take on greater importance and interval training is introduced to develop aerobic power.

• Weekly mileage: 50 to 62 km.
• Long run: increasing from 24 to 28 km, sometimes running the last few kilometres at marathon pace.
• Key sessions: one interval session (e.g., 6 x 800 m), one threshold session (3 x 8 min), two endurance runs, and the long run.

Week 8 serves as a recovery week. Use this time to focus on flexibility, sleep, and nutrition. Starting with this training block, begin incorporating nutrition during the long run: energy gels, sports drinks—everything you plan to use on marathon day. Your stomach needs to get used to it, too.

Block 3: specific training (weeks 11–15)

This is the heart of marathon training. The workouts become highly specific to the distance: you’ll focus heavily on marathon pace so your body memorizes it and executes it without thinking. The long run reaches its peak, preparing you mentally and physically for race day.

• Weekly mileage: 62 to 70 km.
• Long run: increases from 29 to 32–35 km, with substantial segments at marathon pace.
• Key sessions: one session at marathon pace (e.g., 3 x 4 km), one long threshold run (2 x 15 min), one endurance jog, and the long run with full refueling.

The longest run, around 32 to 35 km, usually takes place in week 14 or 15. Do not exceed 35 km: beyond that, the accumulated fatigue outweighs the benefits. Week 12 is a recovery week to help your body absorb this maximum workload. This phase is demanding; it’s what makes the difference on race day.

Block 4: taper (weeks 16–20)

The hardest part is behind you. The last three weeks constitute the taper, this fine-tuning phase where you gradually reduce volume while maintaining some intensity. Goal: to arrive fresh and well-rested, with energy reserves fully replenished. It’s a classic beginner’s mistake to try to do too much at the end; resist the urge.

• Week 16: Volume still high (about 60 km), last big long run of 25 km.
• Week 17: Start of the taper, reducing mileage to about 50 km, with a 20-km long run.
• Week 18: Mileage reduced to 40 km, 16-km long run; continue with short intervals at marathon pace.
• Week 19: Mileage at 30 km, long run reduced to 13 km; let your legs recover.
• Week 20: Marathon week. Minimum mileage of 20 km, a few short jogs with two or three sprints to stay sharp. Complete rest the day before.

During the taper, don’t change anything about your routine: same shoes, same diet, same routine. You might feel sluggish or irritable—that’s normal; your body is recharging. Trust in the work you’ve done over the first 17 weeks.

Mileage summary table

Here is the weekly mileage breakdown. The recovery weeks (4, 8, 12) and the taper (18–20) are clearly marked with a decrease in mileage.

Week	Block	Volume (km)	Long run (km)
1	Base	40	16
2	Foundation	44	18
3	Foundation	48	20
4	Recovery	36	16
5	Foundation	50	22
6	Development	52	24
7	Development	56	26
8	Recovery	44	20
9	Development	60	27
10	Development	62	28
11	Specific	64	29
12	Recovery	50	24
13	Specific	68	30
14	Specific	70	32
15	Specific	68	35
16	Taper	60	25
17	Taper	50	20
18	Type	40	16
19	Type	30	13
20	Marathon	20	42.195 (race)

Adapting to Québec’s climate

A 20-week training program inevitably spans several seasons. If you’re aiming for a fall marathon like the one in Montréal, your heaviest training blocks will fall right in the middle of summer: heat, humidity, and sunshine will be your challenges. Conversely, winter training brings snow, ice, and biting cold. Here’s how to cope with the local conditions.

• Summer heat: Go out early in the morning or in the evening, drink more water, and don’t hesitate to slow down your pace. Exercising in extreme heat takes a greater toll on the body.
• Winter cold: Dress in layers, protect your extremities, and opt for removable cleats on ice. The treadmill remains a valid option for quality workouts during storms.
• Black ice and snow: Safety comes before mileage. Postpone a long run rather than risk a fall.
• Seasonal transitions: Adjust your pace expectations. The body rarely performs the same in humid 30°C conditions as it does in dry 5°C conditions.

Flexibility is your ally. A 20-week program offers just enough leeway to reschedule a session without compromising the overall plan. One imperfect week never ruins a well-structured training plan.

Why 20 weeks instead of 16

The difference between a 16-week and a 20-week plan is significant. Those four extra weeks change the very nature of your training, especially for a first marathon.

• A gentler progression: training volume increases in smaller increments, which significantly reduces the risk of overuse injuries.
• More room for error: a week missed due to a cold or a storm can be made up without stress.
• Full muscular adaptation: tendons and ligaments, which take longer to strengthen than the cardiovascular system, benefit from the extra time.
• Increased confidence: Tackling each new distance without feeling rushed builds mental resilience for race day.

If you’re already an experienced runner aiming for a specific time, a 16-week plan may be sufficient. But if you’re new to the distance, the patience required by a long-distance training plan is a gift you’re giving yourself. You can also check out the marathons in Québec to choose a date that gives you exactly 20 weeks to prepare.

Conclusion

Twenty weeks is a commitment, but it’s also the surest path to a successful first marathon. By sticking to the four training blocks, the recovery weeks, and the final taper, you’ll arrive at the starting line well-rested, well-trained, and confident. Remember: consistency always beats misplaced intensity, and rest is just as much a part of training as the kilometres. Trust the process, one week at a time. When you’re ready to choose your goal, explore the race calendar in Québec and find the marathon that will become your greatest source of pride. Happy training, and we look forward to seeing you on the roads of Québec.