Military Strategies for Sustainment of Nutrition and Immune Function in the Field (1999) / Chapter Skim
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17 Exercise, Infection, and Immunity: Practial Applications
17 Exercise, Infection, and Immunity: Practial Applications
Pages 363-390
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From page 363... ...
, who complained that comparatively little experimental work had been done to test the relationship between exercise and infection. During the past decade, a plethora of worldwide research has greatly increased understanding of the relationship among exercise, the immune system, and host protection.
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From page 364... ...
EXERCISE PRESCRIPTION AND THE IMMUNE RESPONSE TO ACUTE EXERCISE BOUTS From early in this century, it has been regularly reported that during recovery from high-intensity, cardiorespiratory exercise, subjects experience a sustained neutrophilia and lymphocytopenia (Garrey and Bryan, 1935~. Of all immune cells, natural killer (NK)
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From page 365... ...
..~ . 1 1 1 Pre-Run-0715h Post-Run-1000h Post-Run-1130h Post-Run-1300h Post-Run-1600h 365 FIGURE 17-1 Serum cortisol response to 2.5 hours of running at approximately 75 percent v O2max in marathon runners compared with values obtained Dom resting, sedentary controls.
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From page 366... ...
* _~C Pre-Run Post-Run 1.5-h Post-Run 3-h Post-Run 6-h Post-Run FIGURE 17-3 The pattern of change in natural killer cell activity over time in 50 marathon runners who ran 2.5 to 3 hours at 75.9~0.9 percent VO2max.
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From page 367... ...
CHRONIC EXERCISE AND IMMUNITY Ideally, to test the effect of regular physical activity on immune function, a large group of individuals randomly assigned to exercise and sedentary control groups would be followed for at least 1 year with multiple immune measures taken before, during, and after the study. This study, which has not yet been conducted, will require strong financial support before it becomes feasible.
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From page 368... ...
cell cytotoxic activity was 57 percent higher in the marathon runners versus sedentary controls when expressed in lytic units per 107 mononuclear cells.
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From page 369... ...
reported that elite swimmers undertaking intensive training had a significantly lower neutrophil oxidative activity at rest than did age- and sex-matched sedentary individuals and that function was further suppressed during periods of strenuous training prior to national-level competition. Because neutrophils are considered the body's best phagocyte, suppression of neutrophil function during periods of heavy training is probably a significant factor explaining the increased URTI risk among athletes.
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From page 370... ...
Practical Applications for Exercise Prescription These data support the concept that the innate immune system responds differentially to the chronic stress of intensive exercise. with NK cell activity tending to be enhanced while neutrophil function is suppressed (especially during periods of heavy training)
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From page 371... ...
EXERCISE AND UPPER RESPIRATORY TRACT INFECTIONS Among elite athletes and their coaches, a common perception is that heavy exertion lowers resistance and is a predisposing factor to URTI. There is also a common, contrasting belief among many individuals that regular exercise confers resistance against infection.
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From page 372... ...
Average o . ~ _ _ _ ~ Sedentary Moderate Very High Amount and Intensity of Exercise FIGURE 17-5 J-shaped model of relationship between varying amounts of exercise and risk of upper respiratory tract infection (URTI)
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From page 373... ...
At present, there are no published epidemiological reports that have retrospectively or prospectively compared incidence of URTI in large groups of moderately active and sedentary individuals. Two randomized experimental trials using small numbers of subjects have provided important preliminary data in support of the viewpoint that moderate physical activity may reduce URTI symptomatology (Nieman et al., 1990b, 1993b)
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From page 374... ...
EXERCISE AND HIV INFECTION Pertinent questions have been raised regarding HIV transmission during sports that require close physical contact. Most patients diagnosed with active AIDS are acutely and chronically ill and are not likely to participate in athletic endeavors.
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From page 375... ...
Subjects were randomly assigned to either a 12-week exercise training or a counseling control group. Although exercise training had the expected effect of improving both strength and cardiorespiratory fitness in exercise subjects, no significant change in CD4 cell counts or the CD4/CD8 ratio was found for either condition.
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From page 376... ...
Regarding physical activity, national surveys have shown that older adults exercise less and have lower levels of cardiorespiratory fitness than do younger adults. Could regular physical activity attenuate the decrease in immune function with increase in age?
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From page 377... ...
In a randomized study of elderly women, however, 12 weeks of moderate cardiorespiratory exercise training did not result in any improvement in NK- or T-cell function relative to sedentary controls (Nieman et al., 1993a)
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From page 378... ...
. In prior research, carbohydrate versus water ingestion during prolonged endurance exercise had been associated with an attenuated cortisol and epinephrine response through its effect on the blood glucose.
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From page 379... ...
Changes in the function of neubophils, macrophages, and Tand B-cells in response to training have been reported inconsistently, but there is some indication that neutrophil function is suppressed during periods of heavy training. · Limited data suggest that unusually heavy, acute, or chronic exercise may increase the risk of URTI, while regular moderate physical activity may reduce URTI symptomatology.
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From page 380... ...
· Although regular exercise has many benefits for HIV-~nfected individuals, helper T-cell counts and other immune measures are not enhanced significantly. · As individuals age, they experience a decline In most cell-mediated and humoral immune responses.
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From page 381... ...
1993. Supervised exercise training improves cardiopulmonary fitness in HIV-infected persons.
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From page 382... ...
1993. Temporal relationship between decreased salivary IgA and upper respiratory tract infection in elite athletes.
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From page 383... ...
1990b. The effects of moderate exercise training on natural killer cells and acute upper respiratory tract infections.
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From page 384... ...
First, you showed data that vitamin C supplementation reduced upper respiratory tract infections by about 50 percent. But then you
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From page 385... ...
I did not show the other slides. But we have measured every key cell of the immune system: neutrophils, monocytes, natural killer cells, B-cells, and T-cells.
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From page 386... ...
Now, I do want to respond to the first question there, which was on the mechanism of a carbohydrate supplement. There have now been a growing number of both animal and human studies showing very carefully that the stress hormone response carefully tracks the blood glucose response to exercise.
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From page 387... ...
For instance, if you are dealing with young individuals, with near normal responses to begin with, then you do not expect them to enhance that, even though they are sedentary to begin with. If you deal with, say, a population of elderly individuals who for a variety of reasons, including a sedentary lifestyle, have reduced immune responses, then chronic exercise for 4 to 6 months, regular exercise does have a partial or significant effect on resting immune responses and on the incident of common infection.
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From page 388... ...
It had no effect whatsoever. But, when we compared those highly conditioned, lean elderly women with their sedentary peers, where the VO2max of the highly conditioned group was 67 percent higher, which is a huge separation, then we found the natural killer cell activity was elevated.
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From page 389... ...
The phagocytic response goes way up, 85 percent elevation in phagocytic response of Staphylococcus aureus bacteria using flow cytometry. Whereas, the oxidative burst activity is significantly reduced.
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