By Ana Espino | Published on september 23, 2025 | 3 min read
#Immunity #PhysicalActivity
#HealthPrevention #PublicHealth
The
immune system is a cornerstone
of human health, ensuring the
body’s protection against pathogens. Its proper
functioning can be compromised by
stress, aging, sedentary behavior, or
poor
lifestyle habits. In response to these disruptions, medicine often proposes
pharmacological treatments—solutions that are typically short-term, reactive,
and not well suited to a
long-lasting preventive approach.
Physical activity emerges as a
promising, sustainable,
non-pharmacological tool to strengthen immunity.
However, its impact remains ambivalent. While moderate practice improves
natural defenses, excessive or poorly supervised effort can weaken the immune
response and increase susceptibility to infections. This paradox highlights the
importance of better understanding the mechanisms at play and adapting sports
practices to individual capacities.
This study was therefore initiated
to explore how the
intensity, regularity, and
type of physical activity
influence the
immune system.
Too much or too little: When does
effort really protect?
Twenty-four studies were selected, totaling more than 18,000 participants aged
10 to 65 years, exposed to different physical activity protocols. These works
reported both effort parameters (intensity, frequency, duration) and the immune
responses observed. Standardized biomarkers were measured: immunoglobulin
levels, NK cell activity, and concentrations of pro- or anti-inflammatory
cytokines. The analysis made it possible to assess the effect of each type and
intensity of physical activity on immunity, depending on training load.
The results show that
moderate and
regular physical activity effectively strengthens the immune system. It
stimulates the production of defense cells, improves lymphocyte circulation,
and increases immunoglobulin levels, which are essential for fighting infections.
It also acts on metabolism and hormonal balance, contributing to an environment
favorable to overall health. Sports practiced progressively not only strengthen
immunity but also improve physical condition without excessive overload.
Conversely,
overly intense training,
poorly recovered, or
repeated without adaptation can
weaken natural defenses.
It leads to a decrease in immunoglobulins, hormonal disruption, and an
accumulation of toxic metabolites that weaken immune cells. This imbalance—or
“immunity window”—temporarily increases the risk of infection. Proper
recovery—including rest, nutrition, sleep, and alternating efforts—is essential
to maintain stable immunity over time.
Move, yes… but intelligently!
The immune system plays a central role in protecting the body, but it can be
weakened by various factors, including poorly adapted physical activity. One of
today’s challenges is to find the right dosage of effort to stimulate immunity
without disturbing it, particularly among young people and intensive athletes.
This is the perspective in which this study was conducted, to evaluate the
impact of different intensities of physical activity on immune response.
The results confirm that moderate
and regular exercise strengthens natural defenses, while excessive or poorly
recovered training can cause transient immunosuppression. These effects vary
according to training load, recovery quality, and individual profile.
However, the study presents
certain
limitations that highlight the need for
further research. The development of
personalized training programs—taking into account
immune status, age, and
fitness level—represents a promising path. An
interdisciplinary approach,
combining medicine, sports sciences, and human behavior, will be essential to
make physical activity a structuring lever of public health.
Read next: Move to live better?
About the author – Ana EspinoPhD in Immunology, specialized in Virology
