By David Kiefer, MD, Editor
Clinical Assistant Professor, Department of Family Medicine, University of Wisconsin; Clinical Assistant Professor of Medicine, Arizona Center for Integrative Medicine, University of Arizona, Tucson
Dr. Kiefer reports no financial relationships relevant to this field of study.
- All types of exercise have positive effects on the immune system, helping to correct the changes seen with “immunopause”; the only exceptions would be some short-term detrimental effects to exercise that qualifies as high-intensity.
The authors of this literature review detailed changes in immune system function that occur with age, as well as the immunological effects of acute and chronic exercise.
Sellami M, Gasmi M, Denham J, et al. Effects of acute and chronic exercise on immunological parameters in the elderly aged: Can physical activity counteract the effects of aging? Front Immunol 2018;9:2187.
The ambitious title of this review certainly elevates our hopes in the quest to reverse, or at least stave off, the effects of aging. Although not a structured meta-analysis, the authors collected and cited studies across the spectrum of physiology to controlled clinical studies to make an argument for the benefits of exercise on immune system function, focusing on the elderly population. They focused on individuals aged 65 years and older, although they had to extrapolate, at times, from research on younger individuals when studies were lacking. They began their review by detailing the changes in the immune system that occur with age; they used the terms “immunosenescence” and “immunopause.” See Table 1 for some of the changes.
Table 1: Changes in the Immune System and Cytokines That Can Occur With Increasing Age
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- Thymus atrophy
- Decrease in lymphopoiesis (more myeloid cells)
- Decrease in antibody production
- Fewer naïve T cells
- Fewer hematopoietic stem cells
- Increased secretion of pro-inflammatory cytokines (e.g., IL-1, IL-6, TNF-alpha)
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In general terms, the authors mentioned that various types of exercise, at least partly, can ameliorate these immune system changes and inflammation, and even bolster the effect of the flu vaccine, although these effects depend on the type of exercise (e.g., acute vs. chronic; form: endurance, resistance, or sprint; duration; intensity; etc.). Some of these changes are mediated by catecholamines, growth hormone, and glutamine. The researchers also noted that there might be a gender effect on some of the results (i.e., effects seen in men but not women, or vice versa). There also may be effects seen in the elderly that would be different in younger populations, although most of the research has been done on the latter demographic. They expanded on this by splitting the research findings into “acute” and “chronic” exercise; acute exercise involved a single exercise event, whereas chronic exercise was subdivided further into endurance, resistance, and sprint activities. For acute exercise, increased blood flow and other changes may rally immune system cells and stimulate the bone marrow, leading to various improved immunological parameters. (See Table 2.) Most immune system cell lines are affected by acute exercise. Of note, the authors found little to no convincing evidence on changes to cytokines and interleukins.
Table 2: Immune System Changes Shown to Occur After ‘Acute’ or Single Exercise Events
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- Increase in number of monocytes
- Increased neutrophil number
- Increased number of circulating neutrophils
- Longer telomere length in leukocytes (with moderate exercise)
- Increased number of circulating lymphocytes
- Leukocytosis (neutrophilia, lymphocytosis)
- Increased natural killer cell number and function
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With respect to “chronic” exercise (see Table 3), the first category is endurance training, or low-to-moderate effort exercise. With endurance training, there is a general improvement in immune system function, except with long-term intense exercise, which can adversely affect the immune system and lead to an increase in risk for infections. The next category is resistance training, which involves the voluntary use of skeletal muscles. The researchers mention “ambiguity” in the literature, both with conflicting results or no effects, although there may be some changes in neutrophil activity. (See Table 3.) Finally, sprint training usually involves short periods of running exercise, and has a mixed effect on immune parameters, such as decreasing neutrophil function but increasing cytokines.
Table 3: Effects of ‘Chronic’ Exercise, Such as With Endurance, Resistance, and Sprint Training Regimens
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- Tai chi increases circulating myeloid dendritic cells
- Endurance training increases numbers of stem cells
- Increased neutrophil phagocytic activity with resistance training
- Increased cytokines with sprint training
- Decreased neutrophil function with sprint training
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In previous issues of Integrative Medicine Alert, we have reviewed numerous articles touting the benefits of exercise for various demographics. Add to it the results nicely summarized by Sellami et al of exercise, both in general and in the elderly. The effects are complicated and mitigated by many factors, most importantly the type and duration of exercise. And there is a lack of research in the elderly, especially for some exercise types (especially sprint training) and immune parameters (little research on basophils and eosinophils, for instance). Clearly, more data are needed.
Overall, it seems that all types of exercise have some positive effects on immune system function, helping individuals address “immunopause.” However, there are important caveats, such as the fact that intense endurance training or sprint training may compromise immune system function depending on the exact type of exercise. Keeping in mind these risks, this review reaffirms that clinicians can confidently weave in activity recommendations for their elderly patients, individualized based on mobility issues and comorbidities. Both acute and chronic exercise regimens can bolster the immune system in physiologically important ways.
