White Blood Cell Changes After Exercise: Spikes and Drops Explained
Updated on August 6, 2025
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Exercise generally boosts your immune activity and white blood cell count. However, overtraining or prolonged endurance activities can reduce the white blood cell count in some athletes. A low white blood cell count may also indicate a more serious underlying medical condition.
You have five types of white blood cells in your system that help your body defend itself against infection, inflammation, and injury:
- Basophils are cells that help control the immune response and signal other cells when they detect an infection.
- Neutrophils kill bacterial and fungal infections in your body.
- Lymphocytes, including memory T cells, produce antibodies that combat bacterial and viral infections.
- Monocytes live longer than other white blood cells and work to break down bacteria in your system.
- Eosinophils and other granulocytes attack other types of infections, such as parasites and cancer. They are also active during an allergic response.
This article explains how exercise may affect your levels of these.
How Does Exercise Affect White Blood Cell Count?
Exercise typically causes white blood cells to circulate more quickly. In theory, this means that your body may be able to identify infections more quickly, although it’s unclear whether this helps prevent infections in real-world terms.
Research has also shown that one type of exercise may not increase white blood cell count more than another. For example, one study examined white blood cell counts before and after participants ran on a treadmill and cycled on a stationary bike. Levels of every type of white blood cell increased, but no significant difference was evident between the increases due to running or cycling.
The increased white blood cell circulation may be the body’s standard response to the increased stress of physical activity. Having an increased number of white blood cells available may help prepare the body for any injury, inflammation, or infection that might occur.
Can Exercise Lower White Blood Cell Count?
While most types of exercise boost your white blood cell count, in some cases, a low white blood cell count can occur in athletes, especially endurance athletes. It might be an effect of overtraining syndrome, in which a person engages in too much intense physical activity without enough recovery and rest.
The body’s response to acute activity is to release neutrophils from storage in the bone marrow. However, in the case of individuals whose bodies are constantly under stress due to overtraining syndrome, their bone marrow neutrophil stores may be depleted. This means that the immune system may struggle to source enough.
As well as low white blood cell counts, overtraining can also change the composition of your white blood cells. For example, you might have a lower ratio of neutrophils to lymphocytes. Research has also shown lower levels of certain white blood cells, like memory T cells and monocytes, in soldiers going through intensive training.
Other studies have found that when female endurance athletes didn’t consume enough calories to cover the energy expenditure of their physical activity, the researchers observed a white blood cell boost from exercise that was 14.2 percent lower than expected. In neutrophils, the drop was at least 28 percent lower.
However, this study found that the effects were reversible after three days of returning to an optimal energy intake. Despite this, the review on overtraining syndrome found that its negative immune effects may persist even during rest periods.
What is a Normal White Blood Cell Count?
White blood cells, or leukocytes, make up about 1 percent of your blood and are also present in your lymph node tissues.
Your doctor may order a blood test to check your white blood cell count if you are ill or as part of a regular check-up or health screening. A normal range for adults is 4,500 to 10,500 per cubic millimeter. Your white blood cell count may be outside this normal range for many reasons.
An elevated white blood cell count is often a sign that your body is fighting an infection. It may also be a symptom of certain medical conditions, such as myelodysplastic syndrome or myeloproliferative disorder, both of which cause abnormal production of blood cells.
A low white blood cell count can also be a cause for concern. It may be a sign of a serious illness, such as cancer or human immunodeficiency virus (HIV). Some medications, such as chemotherapy, can also lower the number of blood cells in your system.
If your results reveal an abnormal white blood cell count, your doctor may order additional tests to find the source of the infection or disease. Some of these tests may include:
- Complete blood count (CBC), which measures all major blood components, including white blood cells
- Differential white blood cell count, which measures each type of white blood cell
- Neutrophil test, which specifically looks for a low neutrophil count
- Bacterial and viral cultures to detect specific infections in your system
- Imaging tests to further search for possible infection sources
- Biopsy to check for blood cancers if a healthcare professional suspects them
Other Potential Causes of Low White Blood Cell Count
Unless you are exercising for extended periods at an intense level, a low white blood cell count may be a sign of a more serious underlying condition. Disorders and diseases that affect blood cell production in the bone marrow are among the possible causes, including:
- Autoimmune diseases, including lupus and rheumatoid arthritis
- Infections that affect immune function, such as HIV
- Bone marrow disorders, such as multiple myeloma and aplastic anemia
These affect white blood cell production differently. For example, if an individual has aplastic anemia, damage occurs to the bone marrow cells responsible for producing blood cells, resulting in a lower rate of blood cell production.
Myelodysplastic syndromes may also lower white blood cell count. Although blood cell production continues at a normal rate with this condition, the cells are abnormal and often die before reaching the bloodstream. Those that do reach the bloodstream can’t effectively fight infections.
These conditions may be caused by chemotherapy, high levels of ionizing radiation from X-rays or a radiation plant, toxic chemicals including benzene, and certain viral infections. Symptoms may include fatigue, frequent infections, pale skin, red spots on the skin, excessive bleeding, and bruising.
Some viral infections, including HIV and acquired immunodeficiency syndrome (AIDS), may also lower the body's white blood cell count. HIV attacks the immune system, resulting in a low white blood cell count. Individuals with a weakened immune system are more likely to contract infections.
AIDS is the late stage of an HIV infection when the immune system is extremely damaged and the white blood cell count, specifically CD4 cells, a type of lymphocyte, is extremely low. At this stage, individuals are particularly susceptible to opportunistic infections.
Certain cancers, such as lymphoma and leukemia, can also affect the bone marrow and blood cell production, causing a low white blood cell count. Cancer treatments, including radiation therapy and chemotherapy, may also cause white blood cell levels to drop.
Some medications may also lower your white blood cell count. Immunosuppressant drugs, histamine-2 blockers, anticonvulsants, antithyroid drugs, and clozapine are just a few to mention.
Precautions to Avoid Infection
Having a low white blood cell count affects your body's ability to recognize and respond to infections and increases the likelihood that you may become seriously ill. Take precautions to maintain your health while following the treatment plan provided by your doctor:
- Wash your hands frequently using antibacterial soap and water or a waterless cleanser for at least 20 seconds, including under the nails and between the fingers.
- Get all vaccinations as recommended by a healthcare professional.
- Clean any scrapes, cuts, or burns when you get them, keep them dry and clean during healing, and clean your hands before touching a wound.
- Apply antibiotic ointments to wounds, but always obtain a healthcare professional’s approval first.
- Your doctor may recommend wearing an N95 face mask when out in large groups of people.
If you notice any new signs of infection, contact your doctor immediately. Symptoms depend on the particular infection but might include:
- Fever
- Redness, sores, or swelling on the skin
- New or changing coughs
- Diarrhea
- Vomiting
- Nasal congestion
- Breathlessness
- Neck stiffness
- Abdominal or rectal pain
- A sore throat
- New sores in the mouth
The Takeaway
- Generally, exercise boosts white blood cell count, although no research has directly shown that this provides any increased protection against diseases.
- Overtraining can lead to a white blood cell drop, especially if you don’t refuel enough between workouts. This is usually reversible.
- Certain underlying conditions, such as autoimmune diseases, bone marrow disorders, some types of infections, and cancers, can contribute to a chronically low white blood cell count.
- Speak to a doctor if you have concerns about your immune status or experience repeated infections while training.
EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
- Exercise and immunity. MedlinePlus. February 8, 2024.
- Fiala O et al. Beyond physical exhaustion: Understanding overtraining syndrome through the lens of molecular mechanisms and clinical manifestation. Sports Medicine and Health Science. January 29. 2025.
- Leukopenia. Temple Health.
- White blood cells. Cleveland Clinic. July 23, 2021.
- Kodesh E et al. Leukocytes and lactate responses to cycling and running at the same target heart rate. European Journal of Sport Science. March 18, 2024.
- Jeppesen JS et al. Low energy availability increases immune cell formation of reactive oxygen species and impairs exercise performance in female endurance athletes. Redox Biology. June 19, 2024.
- White Blood Cell Count. University of Rochester.
- Myelodysplastic/Myeloproliferative Neoplasms. Yale Medicine.
- Low White Blood Cell Count (Leukopenia). Cleveland Clinic. October 27, 2022.
- Definition & Facts for Aplastic Anemia & Myelodysplastic Syndromes. National Institute of Diabetes and Digestive and Kidney Diseases. July 2020.
- Symptoms & Causes of Aplastic Anemia & Myelodysplastic Syndromes. National Institute of Diabetes and Digestive and Kidney Diseases. July 2020.
- HIV & AIDS. Cleveland Clinic. June 6, 2022.
- WBC count. MedlinePlus. February 2, 2023.
- Infection Prevention in Immunocompromised People. Sepsis Alliance.
- Know the Signs and Symptoms of Infection. Centers for Disease Control and Prevention. November 14, 2024.
Meet Our Experts
Scott Haak, PT, DPT, MTC, CSCS
Medical Reviewer
Scott Haak, PT, DPT, has been a member of the Mayo Clinic staff since 2000. Dr. Haak serves as faculty for the Sports Medicine Fellowship program at Mayo Clinic Florida. He is certified by the NSCA (National Strength and Conditioning Association) as a CSCS (Certified Strength and Conditioning Specialist), is a Certified USA Weightlifting Coach and Certified USA Football Coach, and possesses a MTC (Manual Therapy Certification) from the University of St. Augustine for Health Sciences.
Haak is an exercise enthusiast and enjoys running, weightlifting, and sports performance training. He is the president and director of coaching of a youth tackle football organization, JDL Providence Football, and currently coaches high school football and weight lifting.
Adam Felman
Author
Adam is a freelance writer and editor based in Sussex, England. He loves creating content that helps people and animals feel better. His credits include Medical News Today, Greatist, ZOE, MyLifeforce, and Rover, and he also spent a stint as senior updates editor for Screen Rant.
As a hearing aid user and hearing loss advocate, Adam greatly values content that illuminates invisible disabilities. (He's also a music producer and loves the opportunity to explore the junction at which hearing loss and music collide head-on.)
In his spare time, Adam enjoys running along Worthing seafront, hanging out with his rescue dog, Maggie, and performing loop artistry for disgruntled-looking rooms of 10 people or less.