Guide to What Happens During the Different Phases of a Marathon
Explore the different phases of running a marathon, from start to finish, including physical, mental changes, and recovery tips.
Written by Dr. M L Ezhilarasan
Reviewed by Dr. Mohammed Kamran MBBS, FIDM
Last updated on 30th Sep, 2025
Introduction: More Than Just 26.2 Miles
Running a marathon is not a single, homogeneous event. It’s a story told in distinct acts, each with its own unique physical sensations, mental challenges, and emotional highs. For first-timers and seasoned veterans alike, understanding these different phases of the marathon is the key to crafting a successful race strategy. It transforms the daunting 26.2-mile distance from an unknown monster into a manageable sequence of challenges you can prepare for. This guide will walk you through what happens to your body and mind from the moment the starting gun fires until you’re holding that finisher’s medal. We’ll demystify the infamous "wall," explain the science behind your energy systems, and provide practical tips to navigate each segment. Whether you're aiming for a personal best or simply aiming to finish, knowing what to expect during these different stages will empower you to listen to your body, adjust your effort, and cross the finish line strong.
Phase 1: The Adrenaline-Fueled Start (Miles 1-3)
The energy at the start line is electric. Your heart is pounding, not just from the warm-up, but from a surge of adrenaline and cortisol. This "fight or flight" response is your body’s way of preparing for a major effort. However, this initial burst can be a double-edged sword.
The Physical Reality: Holding Back the Urge
Physiologically, your body is primed to go fast. Your muscles are flooded with oxygen-rich blood, and your glycogen stores are full. The biggest mistake runners make in this phase is going out too fast. The pace feels easy because of the adrenaline, but you are burning precious glycogen at an unsustainable rate. Your pacing strategy must override this feeling. The goal of the first 5K is to settle into your goal pace, even if it feels frustratingly slow. Think of it as banking energy, not time.
The Mental Game: Settling Into Your Pace
Mentally, this phase is about control and observation. Instead of getting swept up by the crowd, focus on your breathing and your form. Check your watch to ensure you’re not exceeding your planned pace. This is the time to establish a rhythm that you can maintain for the long haul. A calm, controlled start is the first and most critical step in a successful marathon journey.
Consult a Specialist for the best advice
Phase 2: Finding Your Rhythm (Miles 4-15)
By mile 4, the crowd has thinned, the adrenaline has faded, and you enter what many runners consider the most enjoyable part of the race. You’ve found your groove.
The Runner's High and Metabolic Shift
Your body has efficiently transitioned into a steady state. Your heart rate and breathing have stabilised at an aerobic level. Many runners experience the famed "runner’s high" during this phase, a feeling of euphoria caused by the release of endorphins. Your body is still primarily using glycogen for fuel, but it begins to tap more efficiently into fat stores. This is where your training pays off—a well-trained aerobic system is crucial for preserving glycogen. This is also the critical window for your fueling and hydration strategy. Taking in easily digestible carbohydrates (e.g., energy gels, chews) and electrolytes every 45 minutes is essential to delay glycogen depletion later on.
Phase 3: The Wall - Confronting the Challenge (Miles 16-20)
This is the make-or-break segment of the marathon, often referred to as "The Wall." It’s not a myth; it’s a very real physiological and mental barrier.
What "Hitting the Wall" Really Feels Like Physiologically
Hitting the wall, or "bonking," occurs when your liver and muscle glycogen stores become critically low. Your body is forced to rely almost exclusively on fat for energy, which is a less efficient process. Physically, this manifests as sudden fatigue, heavy legs, dizziness, and even a loss of coordination. It’s your body’s physiological response to an energy crisis. The reason it often happens around mile 18-20 is that this is typically the point at which the body’s stored glycogen is exhausted, assuming a steady pace and average fueling.
Mental Strategies to Break Through the Wall
Mentally, the wall brings negative self-talk and doubt. The key to breaking through is a combination of physical and mental tactics. First, if you’ve been fueling, take another gel and some water. The glucose can provide a quick boost. Mentally, break the race down into tiny chunks. Don’t think about 8 more miles; think about getting to the next mile marker, or even the next lamppost. Use positive self-talk, focus on your form, and draw energy from the crowd. This is where mental toughness is forged.
Phase 4: The Final Grind (Miles 21-26.2)
The last 10K is a pure test of will. Every system in your body is fatigued, and the finish line feels simultaneously close and impossibly far away.
Tapping into Mental Fortitude
At this point, it’s less about physical fitness and more about mental fortitude. Your pace may slow, and that’s okay. The goal is to keep moving forward. Many runners use tricks like counting steps or dedicating each mile to a loved one. The energy from spectators becomes incredibly powerful—let it pull you along. This final marathon grind is an emotional rollercoaster, often swinging from despair to elation within minutes.
The Physical Breakdown and Mind-Over-Matter
Physically, you may experience cramping as electrolyte imbalances peak. Muscle damage (microtears) causes significant soreness. This is the realm of pure mind-over-matter. Your brain’s "central governor" is screaming at you to stop to prevent damage. Your job is to negotiate with it, reassuring yourself that you are safe and capable. The sight of the finish line can unleash a final, surprising kick of adrenaline, carrying you to the end.
Phase 5: The Immediate Aftermath & Recovery
Crossing the finish line is a monumental achievement, but your journey isn’t over. How you handle the next hour and the following days is crucial for your marathon recovery timeline.
The First 30 Minutes: Critical Recovery Steps
Keep walking for at least 10-15 minutes. Stopping abruptly can cause blood pooling and dizziness. Within 30 minutes, consume a recovery drink or snack containing both carbohydrates (to replenish glycogen) and protein (to start muscle repair). Hydrate with water or an electrolyte beverage. If you experience severe dizziness, nausea, or confusion, seek medical attention immediately at the race’s medical tent. If symptoms like extreme disorientation or chest pain persist, it’s crucial to consult a doctor. You can connect with a specialist online through Apollo24|7 for a quick evaluation.
The Days Following the Marathon
Expect delayed onset muscle soreness (DOMS) to peak 24-48 hours after the race. Light activities like walking, gentle stretching, and foam rolling can aid circulation and recovery. Prioritise sleep and nutrition. The fatigue can impact your immune system, so rest is non-negotiable. If you have unusual pain (sharp, localised) or symptoms of illness, listening to your body is key. For persistent joint pain or to discuss a personalised recovery plan, booking a physical visit to a sports medicine doctor with Apollo24|7 can be very beneficial.
Conclusion: Your Journey, Your Victory
Understanding the different phases of a marathon is like having a roadmap for your greatest running adventure. Each segment—from the controlled start to the rhythmic middle, the challenging wall, and the triumphant final grind—is a chapter in your story. By anticipating the physical and mental shifts, you can move from being a passenger to the pilot of your race day experience. Remember, every marathoner, from elite to beginner, goes through these same stages. Your preparation, pacing, and perseverance are what will define your success. So, lace up with confidence, respect the distance, and embrace each phase of the incredible 26.2-mile journey.
Consult a Specialist for the best advice
Consult a Specialist for the best advice
Dr. Swagata Sircar
General Physician/ Internal Medicine Specialist
8 Years • MBBS, MD General Medicine
Kolkata
HealthYou Speciality Clinic & Diagnostics., Kolkata
Dr. Ashita Kuruvilla
General Practitioner
6 Years • MBBS
Kolkata
KVC CLINIC, Kolkata
Dr. Smitha Nagaraj
General Physician/ Internal Medicine Specialist
15 Years • MBBS, Diploma in Family Medicine
Bengaluru
Apollo Medical Center, Marathahalli, Bengaluru
Dr. Divyashree K
General Physician/ Internal Medicine Specialist
5 Years • MBBS
Bengaluru
Apollo Clinic, JP nagar, Bengaluru
Dr Venkata Naga Sai Tribhushan Rambhatla
General Physician
3 Years • MBBS
Bengaluru
PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru
Consult a Specialist for the best advice
Dr. Swagata Sircar
General Physician/ Internal Medicine Specialist
8 Years • MBBS, MD General Medicine
Kolkata
HealthYou Speciality Clinic & Diagnostics., Kolkata
Dr. Ashita Kuruvilla
General Practitioner
6 Years • MBBS
Kolkata
KVC CLINIC, Kolkata
Dr. Smitha Nagaraj
General Physician/ Internal Medicine Specialist
15 Years • MBBS, Diploma in Family Medicine
Bengaluru
Apollo Medical Center, Marathahalli, Bengaluru
Dr. Divyashree K
General Physician/ Internal Medicine Specialist
5 Years • MBBS
Bengaluru
Apollo Clinic, JP nagar, Bengaluru
Dr Venkata Naga Sai Tribhushan Rambhatla
General Physician
3 Years • MBBS
Bengaluru
PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru
Frequently Asked Questions
What is the most critical phase of the marathon?
While all are important, the first phase (Miles 1-3) is arguably the most critical for setting yourself up for success. Going out too fast can deplete your energy stores early and make the later marathon phases much more difficult than they need to be.
Can I avoid 'hitting the wall' completely?
While you may not avoid it entirely, you can significantly delay and minimise its impact. This is achieved through proper training (long runs to teach your body to burn fat), strategic carb-loading in the days before the race, and a consistent in-race fueling plan.
How should I adjust my pace in the final 6 miles?
Most runners will naturally slow down. The goal is not to push for a personal best in the final miles but to manage the slowdown. Focus on maintaining your effort level, not your pace. If you have energy left, you can push the last 1-2 miles.
What should I do if I experience severe cramping?
Slow to a walk or gentle jog. Try to gently stretch the muscle without forcing it. Take an electrolyte drink or salt tablet if you have one. If the cramp subsides, gradually ease back into your pace. Severe, persistent cramping may require medical attention.
How long should I rest completely after a marathon?
A general rule is one day of complete rest for every mile raced. So, plan for about 26 days of reduced intensity before starting a new training cycle. However, 'rest' doesn't mean inactivity—light cross-training like walking, swimming, or cycling after the first week can aid recovery.