Chronic effects of exhausting exercise and overtraining on the immune response: Th1 and Th2 profile

Abstract

Although physical inactivity figures as one of the main causes attributed to mortality, the damage caused by excessive exercise is also a reality. Professional athletes, amateur or uncompetitive modalities beneficiaries are often affected by deleterious conditions resulting from excessive exercise, such as neurological, endocrine and immune origin. The thin line between losses and benefits of successive fatiguing sessions effort depends on the understanding of concepts and methodological training principles. Exercise may have a paradoxical relationship and its consistent prescription in terms of public health depends on a better understanding of their cellular mechanisms. In this sense, the purpose of this review was to explore a promising topic in sports science, able to contribute to elucidate such mechanisms: Th1 and Th2 profile of the immune response related with chronic exhausting exercise and overtraining.

Molecular Pathways Mediating Immunosuppression in Response to Prolonged Intensive Physical Training, Low-Energy Availability, and Intensive Weight Loss

“…Malnutrition, nutritional deprivation, and low-energy availability are thought to be one of the major causes of immunodeficiency where the most common immune defects are atrophy of lymphoid tissues (e.g., thymus), reduced maturation of T-lymphocytes, an imbalance in the ratio of CD4/CD8 T-lymphocytes, and predominant T H 2 helper cell response (54–59), alterations that were consequently also suggested by the leukocyte transcriptome in our study (Figures 3, 5). These immune system defects have been previously reported to be mediated by reduced levels of leptin caused by low-energy availability and exhaustive exercise (12, 60)—a response also observed in the diet group participants of our study after the weight loss period ( PRE-MID ). On the other hand, leptin administration and moderate levels of exercise have successfully prevented these immune system alterations and consequent immunosuppression (55).…”

Changes in Lymphocyte Composition and Functionality After Intensive Training and Exhausting Exercise in Rats

“…During the exercise recovery, a secondary lymphopenia appears. This seems to be due to a decrease in Th lymphocyte counts through a redistribution of the cells into the non-lymphoid and lymphoid organs (Krüger et al, 2008;Guimarães et al, 2017). In addition, apoptosis also seems to occur unevenly between highly differentiated T cells (Krüger et al, 2016a).…”

Physical Inactivity, Chronic Diseases, Immunity and Covid-19

“…One of the various arguments to encourage moderate and periodic exercise refers to the protection of cells against infections caused by intracellular microorganisms (e.g., viruses), based on the balance between cellular and humoral immune responses, with discreet readiness for the Th1 profile. [17][18][19] For example, data from our group revealed that lymph node cells and mouse macrophage supernatants, after 10 to 12 weeks of moderate exercise, expressed more pro-inflammatory cytokines (e.g., IFN-γ and TNF), while the concentration of anti-inflammatory cytokines (e.g., IL-4 and IL-10) decreased significantly compared to the physically inactive group. 17,18,30 The reduction of the post-intervention IL-10/IFN-γ ratio converged with the hypothesis of the predisposition of the protective cell profile (Th1) with moderate exercise.…”

“…17,18,30 The reduction of the post-intervention IL-10/IFN-γ ratio converged with the hypothesis of the predisposition of the protective cell profile (Th1) with moderate exercise. 15,[17][18][19]30 Furthermore, macrophages of mice infected with the protozoa Leishmania major produced more IL-12 and NO compared to macrophages in the sedentary control group. 17,18 We should also take note of the greater microbicidal activity of these cells and the reduction infection rates and the number of parasites isolated from the paw of infected animals.…”

“…16 The immunity of an asymptomatic and previously "healthy" organism is usually able to resolve intracellular infections. 17,18 Under these conditions, a possible explanation for efficient repair is the balance between cellular and humoral responses, with a slight predominance of the cellular profile, [17][18][19][20][21][22] as its exacerbation can result in tissue damage. 15 However, in situations of cumulative and/or NCD, i.e., when homeostasis is compromised prior to infection, chronic inflammation and/or immunity imbalance would appear to favor cell vulnerability.…”