Guide to Preparing for Your First Marathon: Training and Nutrition

Melanie Ramos 7 min. of reading Running Leave a comment

Facing the 42.195-kilometer marathon distance is one of the greatest physical and mental challenges for any runner. Preparing for your first marathon is not just about accumulating miles; it requires a structured plan that combines training, recovery, and, most importantly, a precise nutrition strategy.

In this guide, we will cover the essential pillars to help you reach the finish line in optimal condition.

Index

1 Training Planning
2 Fueling the 42K
3 From Start to Finish
4 Post-Marathon Recovery
5 Frequently Asked Questions (FAQ)

Training Planning

For first-time marathon runners, the main goal should be to adapt the musculoskeletal and cardiovascular systems to prolonged effort. A standard beginner marathon training plan typically lasts between 16 and 20 weeks, divided into three main phases.

Training Plan Structure by Phase

Phase	Duration	Main Goal	Long Run Reference
Aerobic Base	Weeks 1–6	Adapt the musculoskeletal system, run by time rather than distance	14–18 km
Development	Weeks 7–14	Gradually increase volume and introduce marathon-pace runs	20–28 km
Peak & Tapering	Weeks 15–20	Reach peak workload and progressively reduce training load	28–32 km → reduction

Volume and Intensity

The long run: This is the most important workout of the week. It should progress gradually, peaking at 28–32 kilometers approximately 3 weeks before race day. Its purpose is to train the body to use fat as a fuel source and strengthen mental resilience.
Marathon-pace runs: Once a solid aerobic base has been established, include 6–12 km segments at your target marathon pace within long runs. This is the best race simulation you can perform.
Strength training: A common mistake is focusing only on running. Strength work (core, quadriceps, hamstrings, and glutes) twice per week helps prevent injuries and improves running economy.
Recovery days: Rest is part of the training process. Alternate running days with active recovery or complete rest.

Tapering (Race Preparation)

During the final 2–3 weeks before the race, training volume should be significantly reduced (up to 40–50%). This allows for supercompensation: repairing muscle tissue and maximizing energy stores without losing fitness. Many first-time marathon runners make the mistake of continuing to train hard out of fear of “losing fitness”—the opposite is true.

Fueling the 42K

Nutrition is often referred to as the “invisible training.” Exceptional fitness alone is not enough if energy stores are depleted around kilometer 30 (the infamous “wall”).

The Week Before: Carbohydrate Loading

International sports nutrition organizations, such as the International Society of Sports Nutrition (ISSN), indicate that maximizing liver and muscle glycogen stores is essential for endurance events.

3 days before: Increase carbohydrate intake (aim for 7–10 g of carbohydrates per kilogram of body weight). Reduce fiber and fat intake to minimize gastrointestinal discomfort.
Pre-race breakfast: Consume it 2–3 hours before the start. Prioritize easy-to-digest foods (toast with jam, cream of rice, or specialized complex carbohydrate formulations). Eat only foods you have already tested during training—the race day is not the time for experimentation.

During the Race: Intra-Race Nutrition Strategy

During a marathon, your body will rapidly consume glycogen. To delay fatigue, you need to replenish carbohydrates and electrolytes while running.

Nutrient	General Recommendation (ACSM)	Common Race Sources
Carbohydrates	30–60 g/hour (depending on individual tolerance)	Energy gels, sports gummies, sports drinks
Fluids	400–800 ml/hour (adjust according to temperature and sweat rate)	Water combined with isotonic drinks at aid stations
Sodium	300–600 mg/hour	Electrolyte capsules, fortified gels, or electrolyte drinks
Caffeine	3–6 mg/kg body weight (strategically consumed from km 25–30 onward)	Caffeinated gels, caffeine tablets

Tip: Never try anything new on race day. The months of training, especially long runs, are the perfect opportunity to “train your gut” and determine which carbohydrate formats you tolerate best.

From Start to Finish

Start conservatively: The most common mistake among first-time marathoners is getting carried away by the initial excitement. Maintain a pace slightly slower than your goal pace during the first half—the marathon truly begins at kilometer 30.
Break the distance down: Mentally, do not think about 42 km. Think in 5 km segments (from aid station to aid station).
Stay ahead of thirst: Do not wait until you feel thirsty to drink. Dehydration exceeding 2% of body weight negatively affects aerobic performance.
Follow your nutrition plan: Take your first gel before you feel fatigued, typically between kilometers 8 and 10. Waiting until you experience an energy crash is usually too late.

Post-Marathon Recovery

Crossing the finish line is only the end of the race—it is the beginning of recovery.

First hour (Recovery Window): Prioritize rehydration and consume a combination of simple carbohydrates and high-quality protein (3:1 or 4:1 ratio) to initiate glycogen resynthesis and muscle fiber repair. Recovery shakes are a practical option when appetite is low.
The first few days: It is normal to experience intense delayed onset muscle soreness (DOMS), especially in the quadriceps. Local cold therapy, rest, and a high protein intake can accelerate recovery.
The following weeks: Return to physical activity very gradually. Avoid running during at least the first week and opt for walking, swimming, or cycling (active recovery). As a general guideline: allow approximately one day of recovery for every kilometer raced.

Frequently Asked Questions (FAQ)

Is it necessary to take supplements to run a marathon?
The foundation should always be a balanced diet. However, supplements such as carbohydrate gels and electrolyte drinks are practical, standardized tools that make it easier to meet energy and sodium requirements during the race itself.
What is “The Wall” in a marathon?
“The Wall” refers to the physiological point (usually between kilometers 30 and 35) at which the body’s glycogen stores become severely depleted, resulting in extreme fatigue and heavy legs. A well-planned intra-race nutrition strategy helps prevent it.
How many days per week should I train?
For a beginner marathon runner, 3–4 running sessions per week are sufficient and safe. Adding 2 strength-training sessions perfectly complements the plan without overloading the musculoskeletal system.

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