Running a Marathon: The Complete Guide to 42.195 km

What is a marathon physiologically demanding?

You run a marathon at 75à 85% of your VO2max, significantly lower than a half marathon or 10 km. Paradoxically, that doesn't make it easier, but different. The limiting factor in the marathon is not the intensity, but the duration.

Glycogen management is the central physiological challenge. Your body has enough glycogen for 75à 90 minutes of intensive walking. For most recreational runners, a marathon lasts three à five o'clock. The mathematical conclusion: Your glycogen stores will be depleted somewhere between miles 28 and 35 unless you replenish them during the race and keep your pace slow enough to support fat burning.

The Man with the Hammer is the moment when glycogen depletion hits: a sudden, dramatic decline in pace and mental clarity. Avoidance is possible, but requires discipline in the first half and consistent nutrition along the way.

Running economy has a disproportionately large effect on the marathon. Over 42 km, one percent efficiency improvement means more than a minute of time savings.

Typical times per level

Sub-4h00 for men and sub-4h30 for women is considered a serious recreational achievement. Sub-3h30 puts you in the top twenty percent of participants at most major city marathons. Sub-3h00 is a multi-year project for most runners.

Training structure for a marathon

How far in advance do you start?

A marathon requires the longest preparation of all competition distances:

• Beginners (first marathon): twenty à twenty-four weeks, but only if you already have a solid basic condition of at least three à walking regularly for four months
• Experienced runners aiming for a PR: sixteen à twenty weeks
• Absolute minimum preparation: sixteen weeks, and only for runners who have already run a half marathon

The central pillar: the long endurance run

In the marathon, the weekly long run is sacred. It trains your fat burning, improves your glycogen efficiency, accustoms your tendon and bone system to the accumulative load and builds mental resistance.

The long run always runs at a leisurely zone 2 pace. Never faster. This is the principle that most marathon runners violate: running the long run too fast increases fatigue, increases injury risk and provides no additional training benefit.

Progression over the schedule:

The tempo run: lactate threshold and specificity

One à two tempo runs per week build up your lactate threshold. Pace running intensity for a marathon runner: slightly faster than marathon pace, roughly your half-marathon race pace or slightly slower.

Progression: start with 20 à 25 minutes and build up to 40 à 50 minutes of continuous threshold work.

Marathon pace runs: In the last eight weeks before the race, you sometimes add marathon pace sections to the long run. For example: 25 km total, of which the last 10 à 15 km at or close to marathon pace. This is one of the most specific and at the same time toughest training sessions in any marathon schedule.

Interval training: present but not dominant

In the marathon, interval training plays a smaller role than for shorter distances. VO2max is less restrictive than for the 5 km or 10 km. But omitting it completely is a missed opportunity: a higher VO2max provides a larger reservoir from which your marathon pace is determined.

One interval training per week is sufficient. Keep the volumes modest so that you recover sufficiently for the long run.

Weekly volume

A rule of thumb: the length of your peak week (in km) partly determines the ceiling of your marathon performance. Runners aiming for a sub-4h00 marathon build towards 50à 70 km per week in peak weeks. Sub-3h30 requires towards 70 à 90 km. Sub-3h00 requires 90 à 120 km and more.

Sample schedule for a marathon (sixteen weeks, five training sessions per week)

Race strategy for the marathon

The most critical decision: starting pace

The marathon is won or lost in the first ten kilometers. That sounds dramatic, but it is the experience of almost every marathon runner who has ever started too fast.

Calculate target pace: your desired finishing time divided by 42.195, expressed in minutes per kilometer. Sub-4h00 is 5:41 min/km. Sub-3h30 is 4:58 min/km. Sub-3h00 is 4:16 min/km.

Start the first five kilometers five à ten seconds per kilometer slower than this pace. Not anymore. Taking much more margin also costs time that you cannot regain.

The first thirty kilometers: save

The first thirty kilometers are an exercise in restraint. You feel too good, the crowd gives you energy, everything seems easier than training. That sensation is a lie that you will pay dearly later.

Eat and drink consistently, even when you feel good. Start gels or carbs around mile 10, repeating every 5 à 6 km.

Kilometer thirty: the wall

Somewhere between kilometers 28 and 35, the man with the hammer shows himself to many runners. Glycogen stores drop, pace becomes more difficult to maintain, mental acuity decreases. Anyone who has eaten enough up to this point and has run a realistic pace will pass this point painfully but in a controlled manner.

Anyone who started too fast will be introduced to the dark side of the marathon: a pace that can no longer be influenced no matter how hard you want.

The last twelve kilometers: the real race

Ironically, the marathon only starts at kilometer thirty. The last twelve kilometers are the part that you have mentally prepared during training and physiologically stored through the long endurance runs.

Strategy: split it into four sections of three kilometers. Focus on one piece at a time. Keep up the pace if you can. If it doesn't work: accept, adjust, keep your head up.

Nutrition and hydration for the marathon

Carb loading

Two à three days before the marathon you increase your carbohydrate intake to 8 à 10 grams per kilogram of body weight per day. This maximizes your glycogen stores at the start.

→ Read the complete carb-loading guide.

During the race

• Drink at each food station: water and/or isotonic sports drink
• Take a gel or carbohydrate snack every 5 à 6 km, starting at kilometer 10
• Total carbohydrate intake: aim for 60à 90 grams per hour
• Never eat or drink anything that you have not tested in training

→ More details: nutrition while running.

Frequently asked questions

In summary

The marathon is a race of glycogen management, patience and mental toughness. The physiological preparation revolves around the long endurance run, tempo runs and a calm but consistent weekly volume built up over sixteen à twenty weeks. The race itself is won in the first thirty kilometers by conquering yourself and in the last twelve by persevering.

→ Everything about tapering in the weeks before your marathon: tapering for runners.
→ How to optimally recover afterwards: recovery after a competition.