Effect of Sports Activities on the Immune System

Overview

Objectives:
Normal and moderate exercise can stimulate the immune system. Acute and chronic exercise isa stress, which may have harmful consenquences leading to marked changes in the hormonal, neuroendocrine andimmune systems. However, maximal acute and long-term exhaustive exercise may cause opposite profoundchanges. The aim of the study was to determine the acute and long-term effects of exhaustive exercise on the immuneand endocrine systems. Study design: We investigated 20 top sportsmen between the ages 16 to 18 years. Bloodsamples were collected before exercise, immediately after exercise on a treadmill and after 60 minutes ofregeneration. To determine the long-term effectes, the investigations were performed repeatedly every 3 monthsduring a one-year period. Absolute and percentage counts of lymphocytes and their subsets - CD3 + , CD3 + CD4 + ,CD3 + CD8 + , CD3 - CD16/56 + , CD19, CD3 - CD8 + were determined by flow cytometer. Results - I. acute exercise:Immediately after acute exercise we observed a significant increase of absolute counts of T lymphocytes and theirsubsets - CD3 + , CD3 + CD4 + , CD3 + CD8 + , CD3 - CD8 + - followed by a significant decrease after 60 minutes ofregeneration. The most marked differences after acute exercise were found in the NK cells, which are assumed tobe responsible for defence against viruses and malignancy cells. The mean values of th e NK cells were 340 cc/mlbefore exercise, 1220 cc/ml immediately after exercise and 130 cc/ml after 60 minutes of regeneration. Results - II.chronic changes: There was a significant decrease of percentage counts of CD3 + CD8 + T lymphocyte subsets andNK cells (CD3 - CD16/56 + ) after one hour of regeneration. In our opinion, these changes may be due to the highertraining intensity and may be significant mainly in subjects with daily exhaustive exercise called the „open window“. Conclusions: Our results indicate, that exercise may induce redistribution of lymphocytes between theperipheral lymphatic tissue and the circulation. This may be due to muscle damage, increase of IL6 levels,stimulation of the neuroendocrine system and increased expression of adhesion molecules. Repeated and exhaustivelong-term exercise modifies the immune response and may predispose individuals to more frequent respiratoryviral infections, chronic fatigue syndrome or opportune viral (CMV, EBV) and parasitic (e.g. toxoplasmosis)infections. These facts should be taken into consideration during planning of exercise schedules of top sportsmen.

Key words:
maximal acute and chronic exercise, changes of the neuroendocrine and immune systems,