We Only Eat What We Like – Part 3
For References, please see the previous articles, same title.
Moderate, a.k.a. Pleasurable, Exercise vs. Exhaustive Exercise:
Acute exercise is followed by a mobilization of white blood cells, mainly induced by increased levels of catecholamines and cortisol, both stress-related. NK-cells react the most intensively; they can increase fivefold after intensive exercise. Additionally a weak acute-phase reaction occurs. Most of the time, these changes normalize over twenty-four hours. The humoral immune system may react differently from the pre-exercise levels up to seventy-two hours. Repeated physical exercise, which is typical in sports, is followed only by small changes of immunologic parameters under conditions of rest. Epidemiological studies give clues that the rate of upper respiratory tract infections in athletes can be described by a j-shaped curve. Moderately active subjects have the lowest rate of infection. The influence of exercise on health creates mainly functional changes. But after eccentric exercise immunological cells can be seen in the muscle, as they try to remove destructed tissue [Baum et al. 1997]. A group at the University of Paderborn, Germany [Baum et al. 1997a] investigated whether moderate or exhaustive endurance exercise influences cytokine levels in whole-blood culture supernatants after stimulation. Moderate exercise influenced the γ-IFN production (PHA-stimulated), which increased significantly from 974 (391) pg/ml before exercise to 1450 (498) pg/ml 24 h later. Thirty minutes after exhaustive exercise the γ-IFN level in the supernatants (SEB-stimulated) was significantly decreased (from 14470 (11840) pg/ml before exercise to 6000 (4950) pg/ml after exercise). The IL-1beta and TNF-alpha production per monocyte was also significantly reduced after exhaustive exercise.
After intense long-term exercise, the immune response is characterized by concomitant impairment of the cellular compartment, and increased inflammation. Thus low concentrations of lymphocytes, suppressed natural immunity, suppressed lymphocyte proliferation, and suppressed levels of secretory IgA in saliva are found simultaneously with high levels of circulating proinflammatory and anti-inflammatory cytokines. The underlying mechanisms are multifactorial and include neuroendocrinological (stress) and metabolic factors. The clinical consequences of the exercise induced immune changes have not formally been identified, but the exercise effect on lymphocyte dynamics and immune function may be linked to the exercise effects on resistance to infections [Gani et al. 2003], frequency of allergies and malignancies, and the cytokine response may be linked to muscle damage or muscle cell growth. Moderate, pleasurable exercise across the life span seems to increase resistance to upper respiratory tract infections, whereas repeated strenuous exercise suppresses immune function, with potential dire consequences [Pedersen et al. 2000].
A positive attitude and an active coping style may be very important to keep a healthy immune response. This is of particular relevance for HIV+ subjects. A study was conducted at the University of Miami, Florida [Goodkin et al. 1992] to examine the hypothesis that a psychosocial model was associated with natural killer cell cytotoxicity (NKCC) in HIV-1 infection. A sample of 62 HIV-1 seropositive homosexual men at CDC stages II and III were given a psychosocial battery assessing life stressors, social support, and coping style. Active coping style was directly and positively associated with NKCC, and trends toward a negative relationship of life stressors and a buffering effect of social support on lives stressors were also observed. The results suggest that (1) control variables should be included with psychosocial models and that (2) psychosocial factors, especially active coping, may have a deterrent effect on loss of NK cell function. Active coping style may merit a specific focus in future research of life stressors and the immune system.
Hence, can guilt make you sick? To answer this question, G. Lowe et al.  conducted a study: before producing saliva samples for sIgA assay, 30 subjects listed their pleasurable activities and rated them in terms of pleasure and guilt. Guess what: levels of sIgA were higher in those subjects with high ratios of pleasure-guilt scores!
But exercise is very beneficial to obese people; 58 sedentary obese, males and females, participated in a 12-week aerobic exercise intervention. Despite attaining a lower-than-predicted weight reduction, these individuals experienced an acute exercise-induced increase in positive mood. Exercise should be encouraged -and the emphasis on stressful weight loss reduced [King et al. 2009].
Georges M. Halpern, MD, PhD
Distinguished Professor of Medicinal Sciences
The Hong Kong Polytechnic University
E-mail: [email protected]
PBMC Peripheral blood mononucleated (or mononuclear) cells
ACTH Adrenal corticotrophin hormone
LDL Low Density Lipoprotein
NMR Nuclear Magnetic Resonance
MS Mass Spectrometry
HIV Human Immunodeficiency Virus
NK Natural Killer Cell
HDL High Density Lipoprotein
IgA Immunoglobulin A
sIgA Secretory IgA
TNF Tumor Necrosis Factor
HGH Human Growth Hormone
DOPAC Dihydroxyphenylacetic Acid
SEB Staphylococcal Enterotoxin B
Hs-CRP High sensitivity C-Reactive Protein
GNP Gross National Product
CDC Centers for Disease Control
SUNY State University New York