The word marathon sparks excitement, motivation, and passion in runners. It demands significant physical and mental strength, a commitment to regular and intense training, and special attention to recovery.
Completing such a challenging distance is no easy task. During races, it’s common to see elite athletes collapsing from exhaustion after crossing the finish line, not to mention amateur runners.
Running a marathon puts a tremendous strain on your body, depleting its resources. Your muscles, bones, heart, blood vessels, and even your body’s waste removal system all feel the impact. Your mind becomes fatigued, and your immune system weakens.
For regular and successful marathon running, you need to understand two important aspects:
- What your body goes through during this demanding physical effort.
- How to recover properly after crossing the finish line, and what steps to take first.
In this article, we’ll explore what happens inside your body during and after a marathon, and share valuable tips for effective post-marathon recovery.
Contents
What Happens Inside Your Body When You Run a Marathon
The countdown begins, the starting shot is fired, and you’re off! This is when your body starts to undergo specific changes. Let’s take a closer look at them.
1. Release of stress hormones
Whenever you engage in physical activity, whether it’s running a marathon or simply jogging, your body releases stress hormones.
Scientists call this the “fight or flight” response, a mechanism that dates back to early humans who either chased after prey or ran from danger.
These hormones surge into your bloodstream to prepare your body for the challenge. They trigger a series of changes in your body, which we’ll explain in more detail later in this article. Essentially, all the changes that occur in your body during a marathon are initiated by these hormones.
2. Activation and fatigue of the nervous system
When stress hormones kick in, they trigger the activation of our nervous system, allowing messages from nerves to travel faster to our muscles.
Adrenaline, which serves as both a hormone and a neurotransmitter, plays a significant role in this process, facilitating the coordination between our nerves and muscles.
This rapid communication makes our reactions quicker, our movements more precise, and prepares us for action.
However, during prolonged and demanding physical activities, our nervous system can get tired. One reason for this is the decrease in our supply of neurotransmitters. As a result, nerve signals slow down.
You may experience this as coordination issues, a sensation of muscle weakness, or occasional cramps—it’s as if your body can’t keep up with you.
3. Redistribution of blood flow
One of the functions of stress hormones is to redirect blood flow from internal organs to the working muscles. This helps the muscles receive enough oxygen and efficiently remove waste products. Specifically, blood shifts away from the stomach and intestines, which can lead to discomfort.
- If you have food in your stomach when you start running, the slowed digestion can result in feelings of heaviness, bloating, heartburn, or even diarrhea. That’s why it’s a good idea to choose an easily digestible, mainly carbohydrate-rich meal a few hours before your marathon.
- Because the digestive system functions less efficiently during a race, some runners may have difficulties consuming gels or foods provided at refreshment stations. That’s why it’s important to try out foods in advance to determine which ones your body can handle best during a run.
- After crossing the finish line, your blood doesn’t immediately return to its normal flow; it takes some time to readjust. Therefore, avoid overloading your stomach with a large meal right after finishing to prevent digestive issues.
But since digestion slows down, you may not feel hungry at all. However, it’s still important to have something light and easy to digest about half an hour after finishing. We’ll explain the reasons for this below.
Related: 10 Tips to Avoid Toilet Breaks During a Race
4. Reduction in blood glucose levels
During a run, you can burn up to 700-800 calories per hour. The exact number depends on factors such as your weight, running technique, and intensity, among others. Therefore, some runners can burn 3000-4000 calories during a marathon.
To keep you going strong during a long run, your body relies on glycogen and fats. There are only about 400-500 grams of glycogen stored in our muscles and liver combined. Each gram of glycogen provides around 4 calories of energy. So, on average, the glycogen stores will keep you fueled for about 25-30 km (15-18 miles) if you’re a typical runner.
Of course, this is a rough estimate. In addition to glycogen, the body also uses fats for energy. You get about 9 calories of energy from each gram of fat. However, it takes some time and effort, typically around 30-40 minutes, to transport fat from storage to the muscles, although it’s quicker for those who are well-trained.
Furthermore, fat is used as a primary energy source only during low-intensity activities.
Keep in mind that our body doesn’t have a switch to choose between glycogen and fat. These sources work together, with one taking the lead depending on the situation. Glycogen stores can get significantly depleted, which can result in hypoglycemia—a drop in blood sugar levels.
Maintaining the right blood glucose level is absolutely crucial. It needs to stay within a certain range because both high and low levels can cause serious issues.
Glucose is like the fuel that powers our cells, and it’s essential for their proper functioning. The well-being of all our body systems and organs depends on keeping this balance just right.
Moreover, our brain consumes a lot of glucose. If hypoglycemia develops, it has extremely negative effects on brain function. Since the brain is basically the “control center” of the body, this disruption affects all the bodily processes.
The most severe form of hypoglycemia is a hypoglycemic coma. Without prompt action, it can lead to irreversible damage and even be fatal. To avoid this scary situation, be sure to carefully plan your race-day nutrition.
5. Increase in body temperature
During physical activity, your muscles generate energy, leading to a natural increase in your body temperature. A typical response is an increase of 1-1.5°C, which your body handles well.
However, during a marathon, especially on a hot day, prolonged physical effort can cause your body temperature to increase to as much as 40°C (104 °F). This can lead to potential risks, including extra strain on the heart and disruptions in the excretory system, brain, and other organs.
That’s why it’s important to avoid overheating during a marathon. Don’t skip the aid stations: make sure to drink, drench yourself with water, and use sponges to cool yourself down.
If you notice early signs of heatstroke, such as a rapid heartbeat, confusion, shivering, or cramps, stop running and seek assistance from volunteers or medical staff.
6. Thickening of blood
As your body temperature rises during physical activity, your natural cooling mechanism, sweating, kicks in to prevent overheating.
When sweat evaporates from your skin’s surface, it helps dissipate heat and keeps your body cool. However, on hot and humid days, the process of sweat evaporation becomes more difficult, increasing the risk of overheating.
But here’s the thing: the sweat doesn’t appear from nowhere. When your body temperature starts climbing, heat-sensitive receptors in your skin send a signal to your brain. In response, your capillaries widen, directing more blood to your sweat glands and activating sweat production. This, in turn, leads to your body losing fluids and your blood thickening.
Now, this thicker blood puts extra strain on your heart because it has to work harder to pump it. Moreover, if you don’t replenish your fluid reserves in time, there’s a risk of dehydration. That’s why it’s really important not to pass by refreshment stations.
7. Lactic acid build-up
When you exercise, your muscles produce lactic acid, or lactate, as a byproduct of metabolism. It results from ongoing chemical processes within your cells that provide you with energy.
During less intense workouts, your body can effectively remove lactic acid, preventing fatigue. However, during more intense exercise, there’s a point when the rate at which lactate is produced matches the rate at which it’s used.
This point is known as the anaerobic threshold, and once you cross it, your body can no longer remove lactate, so it accumulates, causing acid build-up.
As a result, you may need to reduce the exercise intensity or temporarily pause physical activity.
The body’s acidity, expressed as pH, is a quite stable indicator. For instance, a healthy blood pH typically falls within the range of 7.35 to 7.45. Going beyond this range can significantly disrupt all metabolic processes.
A shift toward the lower end indicates increased acidity, and if the pH level drops below 6.8, it’s considered incompatible with life.
To delay fatigue caused by acid build-up and avoid the need to drop out of a race, it’s crucial to closely monitor your heart rate. You should be aware of your heart rate zones and make sure you stay within them. This ensures a comfortable and health-conscious completion of a race.
If you reach the anaerobic threshold too early during a marathon, you’ll inevitably hit the “marathon wall” around the 30 km (18-mile) mark. This experience can be quite unpleasant.
Related: At What Mile Do Most Runners Quit a Marathon?
8. Changes in fluid and electrolyte balance
When you engage in prolonged physical activity, your body’s balance of fluids and essential minerals changes. Specifically, it affects minerals such as potassium, sodium, calcium, and magnesium.
These minerals play crucial roles in various bodily processes, including:
- Helping muscles contract.
- Supporting the proper functioning of your kidneys and nervous system.
- Maintaining blood vessel tone, among other functions.
During exercise, your body’s need for these minerals increases, mainly because they are actively lost through sweating. That’s why, during races, it’s a good idea to keep yourself hydrated not only with plain water but also with isotonic drinks and similar options.
9. Onset of nasal congestion
Another common issue that many runners experience is nasal congestion, which can suddenly appear during a run. There may be a few reasons for this:
- While running, you breathe more deeply and actively, potentially inhaling more allergens. If you have allergies, they may become noticeable during your run.
- Prolonged physical activity can dry and irritate the inside of your nose. In response to this irritation, your body actively produces mucus, which is especially noticeable when the air is dry and/or cold. The good news is that this nasal congestion usually goes away on its own after you finish your run.
10. Changes in height
As you run, each step involves pushing off from the ground and then landing. This is when your body experiences an impact load, and its intensity depends on various factors such as the length of your run, your body weight, running technique, shoe cushioning, and more.
Due to gravity, impact loads, and dehydration, the intervertebral discs and cartilage can actually shrink in height. So, by the time you cross the finish line, you might find yourself a bit shorter than when you started.
In general, this is a normal physiological process. Even if you aren’t a runner and measure your height in the morning and evening, you might notice a little difference.
To prevent irreversible changes in the spine and joints, try to avoid high-impact activities for at least a few days after a race. Instead, opt for stretching and relaxing activities such as swimming.
What Happens to Your Body After a Marathon
All the processes and changes that occur in your body during a marathon naturally affect how you feel right after crossing the finish line. Let’s explore what you may experience at that moment and how to improve your condition.
1. Muscle pain
First and foremost, you’re likely to experience muscle pain and stiffness, commonly referred to as muscle soreness.
Muscle pain following physical activity comes in two types, depending on its cause:
- Pain experienced during or immediately after exercise.
- Pain that appears a few hours or even the next day, known as delayed-onset muscle soreness.
The reason for the first type of pain is lactic acid. However, it usually goes away pretty quickly—within half an hour to a few hours, depending on the intensity of your workout.
The second type of pain occurs due to micro-injuries and micro-tears that inevitably happen in the muscles during heavy, intense, and lengthy workouts.
2. Joint pain
After finishing a marathon, you might also experience joint pain, mainly in your ankles, knees, and lower back.
The discomfort is caused by the continuous impact load, and it can be more intense if you have issues with your technique, carry extra weight, or wear shoes without sufficient cushioning.
3. Swelling
In the case of injuries, even minor ones, damage to the cell membranes can cause fluid from inside the cells to leak out, resulting in swelling. This excess fluid can put pressure on the nerve endings in your muscles, causing pain.
Moreover, it can disrupt the flow of blood and lymph, further contributing to the swelling.
4. Disruption in kidney function
Swelling can also be linked to disruptions in kidney function. The kidneys continuously filter the blood circulating through the body, removing waste products. They undergo a significant workload during a marathon, especially in hot weather when runners may not drink enough water.
There has been some research on this topic. For example, in 2015, a team of scientists led by Professor Chirag Parikh studied a group of runners who participated in the 2015 Hartford Marathon. They examined blood and urine samples collected before and immediately after the race.
The study revealed that after the marathon, 82% of the runners experienced the initial phase of acute kidney injury. This means that their kidneys almost stopped filtering the blood.
Related: What to Do if You Feel Unwell After a Race
Factors contributing to this condition include the increase in body temperature during the race, dehydration, and reduced blood flow not only to the kidneys but also to all internal organs.
Usually, this condition goes away within a few days after running a marathon. However, it can also lead to longer-lasting and adverse effects.
5. Insomnia
Prolonged and intense physical exertion places significant stress on the body, which can potentially lead to insomnia. This condition can be worsened by an overworked nervous system and overall excitement, causing some runners to experience difficulty sleeping after a marathon.
Conversely, some sleep quite well after intense exercise, especially if they didn’t get enough rest the night before a race.
6. Apathy and mental slump
On the one hand, engaging in sports boosts the production of dopamine, a hormone that provides a sense of satisfaction when we reach our goals and keeps us motivated. On the other hand, a marathon is a demanding challenge that isn’t always enjoyable and can leave you feeling mentally drained.
Moreover, many runners set the goal of completing a marathon simply to cross it off their bucket list.
Participating in a marathon can deplete your emotional energy to the extent that the next day, you might find yourself in a mental slump, and getting out of it is not that simple. You’ve already achieved a significant athletic victory, but what’s next and why you should keep training might feel uncertain.
That’s why, after experiencing physical and emotional stress, your body needs peace and relaxation.
Related: 7 Tips on How Not to Lose Passion for Running
7. Weakened immune system
After intense physical activity, your immune system weakens because increased cortisol levels break down the immune cells that protect you from viruses and bacteria.
Running a marathon places exceptionally significant stress on your body, leaving your immune system almost defenseless. This makes you highly vulnerable to catching a cold even from a gentle breeze.
8. Increased resting heart rate
A few days after running a marathon, you might notice a higher morning heart rate. This is a normal reaction to intense physical stress—your heart needs a break too.
Usually, your heart rate returns to its regular range as you recover over a few days. If it doesn’t and you experience chest discomfort or irregular heartbeats, seek immediate medical attention.
10 Tips for Recovering After a Marathon
Understanding what happens in your body during and after a marathon helps you plan your recovery more effectively.
Experienced athletes may recover in a couple of weeks, but for average runners, it could take a month or longer.
The important thing is not to rush and give yourself the necessary time. With the right recovery approach, your body can return to normal in 2 to 3 weeks.
Now, let’s explore methods to speed up your post-marathon recovery.
1. Cool down your body
Recovery should begin right after you cross the finish line. Resist the urge to sit or lie down; instead, start with a proper cool-down routine.
You can do a light jog or take a leisurely walk. Afterward, do some gentle stretching, but be careful not to pull your ankle too far back toward your thigh, as this could lead to cramps.
Cooling down helps your body get rid of lactic acid more quickly, relaxes your muscles, and gradually shifts your body from an active state to a state of rest.
2. Change into dry clothes
As tempting as it may be to just collapse and rest after completing a race, it’s not the best choice. Well, you can do it, but first, change into dry, warm clothing!
If the weather is cool, and you ran in shorts, grab one of those foil blankets that are often given out at races and use it to get to the changing area.
After completing such a challenging race, your immune system is at its weakest, leaving you more vulnerable to illness. To lower this risk, be cautious for a few days: avoid getting too cold or getting soaked in the rain, and stay away from drafts. If possible, steer clear of crowded places.
3. Lie with your legs up
Micro-injuries, poor lymphatic drainage, and resulting swelling can cause significant discomfort. Lying down with your legs up can help in this situation as it promotes better lymph flow. However, be sure to do this after completing your cool-down routine, changing into dry clothes, and preferably in a warm place.
4. Use compression gear
Consider using compression socks or sleeves right after a race. They can help improve lymph flow, boost microcirculation, reduce swelling, and relieve muscle tension.
5. Apply ice
To ease muscle pain, you can apply ice to your legs, but do this only when it’s hot outside. Make sure you place the ice directly on the sore muscles and joints.
Jumping into an ice bath or taking a cold shower right after a race isn’t a good idea, as it can cause blood vessels to constrict and lead to overcooling.
6. Replenish your glycogen stores
Running a marathon makes you burn a massive amount of energy, so it’s crucial to refuel. However, because your digestive system slows down during and after a race, it’s best not to rush into eating.
Wait for about 20-30 minutes, then have something light and rich in carbohydrates, such as a banana, an energy bar, or granola.
A few hours later, you can enjoy a full meal. The best choice is a combination of protein and carbohydrates, like lean meat with a side dish.
Protein is essential for repairing muscles and recovering from those micro-injuries, while carbohydrates help replenish your glycogen stores—a process that may take a few days.
7. Restore your water and electrolyte balance
In addition to restoring your protein and carbohydrate stores, it’s crucial to replenish your water and electrolyte balance. Take small, frequent sips of water to avoid putting extra strain on your kidneys, which are already stressed, and to prevent swelling and other negative effects.
To replenish the essential minerals that your body used up and prevent any potential deficiencies that could harm your health, switch between drinking plain water and isotonic beverages.
8. Rest well
Getting a good night’s sleep is important for proper recovery after a marathon. If you have difficulty falling asleep after intense physical activity, consider taking a melatonin supplement and replenishing your magnesium levels.
9. Give yourself a short break from running
It’s a good idea to skip running for a few days after completing a marathon to allow your musculoskeletal system and heart to rest and recover. Go for leisurely walks and do some light stretching.
Another excellent option is swimming, as the water promotes relaxation and provides a massage-like lymphatic drainage effect.
10. Consider a massage and self-myofascial release, but wait a few days
Massage is a great recovery technique, but it’s best to wait a few days before scheduling one.
Right after a marathon, your muscles are fatigued, and you may experience discomfort from micro-injuries and swelling. A massage during this time won’t provide much benefit.
In conclusion, we would like to emphasize that running a marathon places significant stress on your body, whether you’re an experienced or amateur athlete.
While some may say that the impact of a marathon on the body is unpredictable, the reality is different. Everything that occurs in your body during a race follows a logical and understandable pattern. All you need is some basic knowledge about these physiological processes.
Knowing what to expect allows you to take preventive steps and avoid unpleasant consequences.
