Back to SpecialtiesThis paper gives recent information about immunologic changes of exercise as well as the effects of regular exercising on persons infected with HIV and the recommendations related with exercise for these people.
According to the concept of psychoneuroimmunology, any stress seems capable of changing immune function. As an example , we can use surgical patients in which the T lymphocytes falls after the operation and the worsening of immunity after alcohol consumption.
It is yet unclear if these changes , especially those from an everyday life(walk, sleep, houseworks), are clinically important, however it seems likely that psychological stress can increase the vulnerability of immunologic system. It was shown in an Australian community , in which adjusted the risk factors , people with greater degrees of stress had more upper respiratory infections than those with less stress . In addition , relaxation seems to improve immunity , increasing salivary IgA, for example. If all the aforementioned is true , no wonder the stress of physical exercise , and all that goes with it, seems to be able to alter certain features of immunity.
Immunity Changes During Exercising
The researches interest today centers on the exercise associated changes in numbers or function of lymphocytes and the implications with viral infections , especially HIV infection.
Exercising increases the white blood cell (WBC) count in proportion to the effort. During exercise there is a rise in granolocytes (mainly PMN), monocytes, and lymphocytes. Among the lymphocytes subset, NK cells usually increase most during exercise. This increase in WBC is, no doubt, mediated by mechanical effects of increased cardiac output (WBC enter the blood from reserve pools in lung, liver, and especially the spleen) and a surge in blood adrenaline concentration.
However, exercising lymphocytosis is brief and it begin to fall 5 minutes of ending the exercise and 1 hour late may be below the preexercise baseline. It could be correlated with the level of cortisol . Usually after 4 to 6 hours the lymphocyte count is back to the baseline.
The function of lymphocytes and NK cells seems to increase during exercise, even when it is a light exercise. It is mediated by releasing of adrenaline and cytokines . However , lymphocyte mitogenesis is blunted in the late stages of exercise, which is influenced by cortisol. The temporary enhancement of NK activity by exercise occurs whatever the exerciser’s sex, age, fitness, or trainment . Once habituated, the NK enhancement falls off in response to stress, not to the exercise per se.
Few researches were made about the changes in blood levels of immunoglobulins. There are some studies suggesting little increase with moderated exercises and decrease with endurance exercises.
Exercising also increase the blood level of PMN cells. There is an increase during exercise and 2 to 4 hours later. The delayed rise in PMN is probably mediated by cortisol, which spurs release from bone marrow and hinders regress from the blood stream. Cytokines released from damaged muscles also contributes to leukocytosis after exercise. Although increased in number, the PMN activity decreases , with a resultant decline in phagocytic defence against infections. Another interesting fact is that strenuous exercising may lead to enough tissue damage to evoke acute phase response . This response can modulate immune response activating complement , releasing TNF , interferons , interleukins, and others cytokines.
HIV infection has an unique relationship to immune responsiveness and exercise. The HIV directly affects the immune system. If exercise has clinically significant effects on immune responsiveness, it could have the potential to alter the natural history of HIV infection in a beneficial or deleterious manner.
There is no need now to explain the natural history of HIV infection, but it is good to remember that the progress in development of anti-retroviral medications and drugs for oportunistic infections has given for infected patients a increase in time and quality of life. This can enhance the aderence to exercising programs , not only to have a well being , but to increase the potential of survive with greater quality of life.
More than never our society is giving a great importance to health and exercise. It is not a surprise that many HIV infected individuals wish to realize some kind of exercise. Fortunately now, there are evidences showing that exercise is safe for infected patients and, in addition, it could offer physical and mental benefices.
Some studies demonstrated that exercise is able to increase CD4+ cells of HIV infected individuals. Due to it, safety and benefices are being attributed to specific exercise programs, not only at physical , but mainly at phsicological aspect . The moderated aerobic exercises can be very beneficial for assymptomatic infected patients and for patients at early phase of disease. In patients with more advanced disease studies demonstrated a lower number of oportunistic infections, however many patients developed AIDS related symptoms.
In relation to competitive participation , preliminary dates suggest that in non-professional competitions the trainment component may be beneficial , but it is yet early to conclude anything about competition for elite or professional athletes HIV infected. The exercise per se would be safe for professional athletes too, however these individuals are exposed to high levels of stress and this aspect depend on a lot of different factors, what makes hard to take any conclusion just about the effects of exercise.
Participation in exercise programs can lead to increased strength and body mass , which is very relevant to HIV patients because wasting is one of the most terrible aspect of infection. The wasting in HIV infection is likely to be multifactorial (TNF, IL-1, malabsortion , perturbations of energy balance) which leads to loss of body mass with little loss of fat.
Lethargy and fatigue, which is characteristic of advancing HIV infection may be a compensatory mechanism to help conserve body mass in the presence of increased resting expenditure of energy. So it is important to know that exercise , including strength training, may have the potential to reverse (at least temporary) these wasting trends. Limits for strength training , however, must be defined yet.
The benefits of exercising may result from the direct effect on immune response modulation (in particular cortisol and adrenaline) or from the mechanism of psychological effects of exercise . The ability of exercise training to reduce anxiety, stress and depression as well as to lead to improved self-esteem have been well documented.
1- DeSales Lawless, Catherine GR Jackson and John E. Exercise and Human Imunodeficience virus (HIV-1) infection. Sports Med. 19 (4) 235-239 1995
2-Shephard et al. Physical activity and the Immune System. Sports Med. 18 (5) 358-363 1995
E.Randy Eichner, MD, and Leonard H. Calabrese, DO, FACP. Immunology and Exercise . Medical Clinics of North America, Vol 78 Num 2 March 1994
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