Few accomplishments rival the feeling of crossing the finish line after months of marathon training. With participation in marathon events continuing to grow across the United States and around the world, more runners are experiencing both the triumph of race day and the challenges of recovery that follow.

One of the largest marathons is coming up soon!  The New York City Marathon, whose course winds through all five New York City boroughs.  The streets will be lined with spectators throughout the entire course. Only 127 runners participated in the inaugural running of the NYC Marathon in 1970 and only 55 of these participants finished.  Today, the NYC Marathon will host more than 50,000 runners!  While many will train for and run this event, many will also make mistakes when recovering from completing the marathon.  Before we discuss optimal measures in recovering from running a marathon, we will break down physiologically what happens to the body in the two weeks after completing this incredible feat.

THE OBVIOUS:  MUSCLE SORENESS

Probably one of the most obvious systems to be affected is the musculoskeletal system.  Soreness from running a marathon is primarily due to Delayed Onset Muscle Soreness or DOMS, which can be described as microscopic tears within the muscles that occur 24-72 hours after a workout.  DOMS can be further described as a type of muscle fiber necrosis and inflammation with an increase in leukocytes and other phagocytic cells within the extracellular and extravascular spaces.  While many will recover from this within a few days, some may feel the effects from muscle breakdown for 2 or more weeks after the event.

Increases in creatine kinase (CK) and creatine kinase myocardial band (Ck-MB) have been found in the serum of marathon runners after a race, indicating diffuse muscle damage and in some cases, even rhabdomyolysis.  CK values may increase rapidly after the marathon.  Elevated levels of myoglobin and lactate dehydrogenase (LDH) have also been observed after the completion of a marathon, which in combination with the other biomarkers, indicates the death of muscle cells.  Inadequate rest after a marathon may result in muscle strains and tendinopathies.

TEMPORARY CHANGES IN CARDIAC FUNCTION

Marathon running has been shown to induce acute changes in circulating levels of myocardial biomarkers and moderately alters chamber volumes and cardiac function (Laily  et al 2026). In fact, multiple studies have reported elevations of cardiac biomarkers during and after the completion of a marathon, suggesting myocardial damage.  Elevations in cardiac troponin-I, creatine kinase (CK) and creatine kinase myocardial band (CK-MB), myoglobin, atrial natriuretic peptide (ANP) and N-terminal prohormone of brain natriuretic peptide (NT-proBNP) have been observed.  Braschler et al 2025 performed a comprehensive review of the benefits and risks of marathon training and racing on different organ systems and saw a correlation between recreational athletes training less than 35 miles per week before a marathon and higher cardiac biomarkers.  The elevation of cardiac troponins and NT-proBNP after the race was significantly associated with a decrease in pumping efficiency or diastolic dysfunction.  Nevertheless, in most marathon participants, cardiac biomarkers were only transiently elevated and typically returned to baseline levels within 72 hours after the race.

ILLNESS/INFECTION:

An increase in cytokines and a decrease in neutrophils and lymphocytes is often found after running a marathon which can lead to systemic inflammation.  This increase in inflammation can induce risk for upper respiratory infections and other infections, with a peak elevation between 3-72 hours post-race.

Another common problem apart from changes in lung volumes is respiratory muscle fatigue.  Lung function is temporarily reduced during marathon running due to a combination of obstruction, restriction, and muscle fatigue.  Many marathons often take place in large cities with varying air quality which may also increase the risk for allergies and respiratory fatigue.  The runner may become more susceptible to upper respiratory tract infections (URTI) not only due to a decrease in lung function but also due to the mild airway obstruction from more heavily polluted cities or even cities with higher allergens.

Strenuous exercise, including that of marathon running, can also place a huge stress on the kidneys. Microscopic hematuria may develop after running a marathon which indicates a large increase in urinary biomarkers and therefore the potential for acute kidney injury (AKI).  Dehydration is the most obvious cause of AKI, but other factors may shift blood volume away from the kidneys and other major organs.  Excess sweating will send a signal to the body to shift blood volume towards the muscles and skin and away from internal organs.  The kidneys compensate for this shift by activating neurohormonal and hemodynamic pathways to preserve systemic blood pressure and renal perfusion (Girish et al 2026).  The use of ibuprofen or other NSAIDs during exercise may also lead to AKI as it marks the need for the kidneys to filter the medication which will decrease the effectiveness of the kidneys to assist in electrolyte balance (Mikkelsen et al 2009).

Increased levels of cortisol following marathon races may also suppress the ability to fight off infection.  Cortisol can also lead to poor sleep which will further hinder the ability to reduce the risk of illness or infection.

Gastrointestinal (GI) symptoms are common after running a marathon and may be a cause of multiple factors.  The three main causes of GI symptoms stem from physiological, mechanical or nutritional mechanisms.  During strenuous physical exercise, norepinephrine is released which induces splanchnic vasoconstriction.  This splanchnic blood flow may be reduced by up to 80% to provide sufficient blood flow to working muscles and skin (for cooling).  Gut mucosa may then become susceptible to ischemia.  Gastric emptying may be reduced by dehydration.  During prolonged exercise, absorption of water and carbohydrates may be reduced as well.  Under normal conditions the gut is only able to absorb about 60 grams of carbohydrates per hour, but many runners are exceeding this not only during the run but also in the days leading up to the race as they carb load.  The increase in vibration of the abdominal wall during running may cause bouncing of the intestines which may lead to GI symptoms.  The use of NSAIDs can also increase GI permeability and lead to GI symptoms (Oliveira et al 2014).

BRAIN FOG:

During marathon running, the body will first turn to carbohydrates as the primary source of energy.  However, when carbohydrate stores are low, it will turn to fatty oxidation, which is the utilization of fat as an energy source.  Meylin, the sheath that encompasses nerves, is 70-80% composed of lipids. Myelin was found to be substantially reduced after marathon running but is temporary and reversible (Ramos-Cabrer et al  2024).   Some runners may experience temporary symptoms often described as “brain fog,” including difficulty concentrating, mental fatigue, and reduced short-term memory. These symptoms can be further exacerbated by dehydration and poor sleep the days after the race.

RECOVERY AFTER THE MARATHON:  COMMON MISTAKES

Now that we have discussed what happens physiologically during a race, let’s talk about where many runners go wrong after running a marathon.

BEER!

Runners will see a lot of funny signs held up by spectators during the marathon.  One of the more common signs is “Beer at the end!”  And while post-race events can be a lot of fun and yes, many will crave a cold brew at the end, drinking a beer before replacing fluids and carbohydrates can lead to increased dehydration which can in turn lead to acute kidney injury (AKI), GI distress, headache, muscle cramping and fatigue and even increased risk of illness/infection.  Elevated liver biomarkers after marathon running are common as well and may show peak values 48 hours after the race and could lead to acute liver failure in individuals that already have elevated liver enzymes.

EATING WHATEVER WE WANT

Okay, yes, absolutely celebrate with your favorite meal after the race.  But eating whatever you want for 2 weeks after the marathon will only delay recovery.  Continuing to eat foods that are high in fat and low in good nutritional value may continue to wreak havoc on the GI system, which is often one of the most affected systems during and after running a marathon.  Fatty foods can also delay liver recovery.  And foods that are not rich in antioxidants can delay recovery of the inflammatory system.  For optimal recovery, ingestion of foods rich in complex carbohydrates will help to restore glycogen stores.  Lean proteins will help repair muscles.  Omega-3 fatty acids (e.g. salmon and other oily fish, flaxseed, edamame and chia seeds) are important for cardiovascular recovery and foods rich in antioxidants (e.g. cherries, berries, nuts, dark leafy greens such as kale and spinach) can decrease overall inflammation.  A study by Divya 2019 found that both synthetic and natural antioxidants significantly reduced oxidative stress and inflammation, but natural antioxidants were superior to synthetic over time.

LACK OF SLEEP

Completing a marathon is a great reason to celebrate but it is important to prioritize sleep in the two weeks following a marathon.  Runners should make sure that celebrations do not cut into the ability to get 7-10 hours of sleep each night while recovering.  Good sleep reduces the risk of illness and increases recovery from marathon running through the release of testosterone and human growth hormone (HgH).  Poor sleep can increase the production of cortisol which can increase the risk of illness.  Cognitive decline, which may already be reduced by the transient decrease in brain myelin after running a marathon, may also be exacerbated by lack of good sleep.

ICE BATHS

Cold water immersion may help to restore subjective fatigue measures (Wiewelhove et al 2018).  However, a 2015 study by Leeder et al. found that an ice bath did not promote recovery in subjects with DOMS.  While cold water immersion may reduce soreness and perceived fatigue, some research suggests it may also blunt certain muscle adaptation and protein synthesis responses.  Fuchs et al 2020 found that cooling via cold water immersion post-exercise during recovery lowers the capacity of the muscle to take up dietary protein.

ANTI-INFLAMMATORY DRUGS (NSAIDs)

Myosatellite cells, or satellite cells, are found in muscles, and their job is to attach to existing fibers to form new fibers.  This process occurs during normal muscle growth as well as during recovery from injury.  It is theorized that NSAIDs greatly reduce the spread of these cells, thus hampering muscle recovery and growth (Mikkelsen et al 2009). In essence, we want our body to go through the normal healing process and the first stage of healing is inflammation.

FLYING HOME IMMEDIATELY AFTER RACE

Flying soon after a marathon transiently raises venous thromboembolism (VTE) risk because endurance exercise and air travel each independently promote a hypercoagulable state, and their combination is compounded.  Both marathon running and prolonged flight activate coagulation and impair the normal balance of fibrinolysis; prolonged immobility, cabin hypobaric hypoxia, low humidity and dehydration during flight compound the post-race prothrombotic shift.  The risk is low but is still in essence a risk.  Flying immediately may also increase the risk for illness/infection due to suppressed immune system (Braschler et al 2025).

AGGRESSIVE STRETCHING TOO SOON

Overstretching a muscle can cause injury.  Myofascial release performed on an area of potential injury may worsen the injury.  So while stretch labs, massage therapy or any other form of stretching are not bad, one must be careful not to allow themselves to be stretched too far.

RETURN TO TRAINING TOO SOON

In general, return to intense training could be detrimental while multiple systems in the body are recovering from elevated markers as mentioned above.  Although formal return-to-running guidelines are limited, I often use the practical rule of one day of complete rest for every 10 miles raced for experienced runners.  So, for a marathon, this is 2-3 days of no running.  Then, no high-intensity running for 2 weeks.  After 2 weeks from the marathon, one may begin by adding 4-6 short strides of 15-20 seconds a couple times after an easy run for the first week or 2 and see how the body adapts.

 It is also recommended that the athlete monitor their resting heart rate (RHR) and their heart rate variability (HRV). If an athlete has monitored their RHR prior to the race, they can use that number to see if they are recovering adequately.  An elevated RHR will likely indicate incomplete recovery and ongoing fatigue so steps should be taken to continue recovery before increasing intensity with workouts.

HRV was first used to predict cardiac death and diabetic abnormalities but has recently been found to give coaches and athletes great insight into their training and recovery.  HRV measures variation in time between each heartbeat and can now be monitored through most smart watches.   Higher HRV generally points to good recovery and cardiovascular fitness.  This high measurement may tell us that the body is easily able to shift between stress and relaxation.  However, a low HRV may indicate poor or slow recovery and may also predict future illness and/or injury if one does not take measures to get good sleep and recovery.

Finally, for runners completing their first or second marathon, the body will likely take longer to adapt to changes and recovery so 2 weeks of no running may be recommended.  During this time, it is often recommended that one stay lightly active, however, as the body will often recovery better through active recovery versus complete rest.  So even though it may be recommended to refrain from running, light activity such as walking or light cycling, yoga, etc, can help speed up recovery.

Crossing the finish line is only part of the marathon experience. The physiologic stress of running 26.2 miles extends well beyond race day, and how runners recover during the following two weeks can significantly influence their health, performance, and readiness for future training. Prioritizing hydration, nutrition, sleep, and gradual return to activity may be the difference between thriving after the race and lingering fatigue for weeks afterward.

OTHER USEFUL RESOURCES:

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Divya C. Comparative study of synthetic vs natural antioxidants in inflammatory diseases. Eur Jour of Cardiovasc Med 2019; 9: 2042-4892.

Fuchs C, Kouw I, Churchward-V, Smeets J, Senden J, van Marken Lichtenbelt W, Verdijk L, van Loon L. Postexercise cooling impairs muscle protein synthesis rates in recreational athletes. J Physiol 2020; 598: 755-772.

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