Benefits of oat b-glucan and sucrose feedings on infection and macrophage antiviral resistance following exercise stress. Am J Physiol Regul Integr Comp Physiol 297(4):R1188-R1194

Division of Applied Physiology, Department of Exercise Science, Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, USA.
AJP Regulatory Integrative and Comparative Physiology (Impact Factor: 3.11). 08/2009; 297(4):R1188-94. DOI: 10.1152/ajpregu.00396.2009
Source: PubMed


Oat beta-glucan can counteract the exercise-induced increased risk for upper respiratory tract infection (URTI) in mice, which is at least partly mediated by its effects on lung macrophages. Substantial evidence in humans indicates that carbohydrate-containing sports drinks can offset the decreased immune function associated with stressful exercise. However, no studies in animals or humans have directly examined their effects on URTI using a controlled virus-challenge model. We examined the effects of sucrose feedings alone and in combination with oat beta-glucan on susceptibility to infection and on macrophage antiviral resistance in mice following stressful exercise. These effects were also examined in rested, nonimmunocompromised control mice. Mice were assigned to one of four groups: H(2)O (water), sucrose (S), oat beta-glucan (ObetaG), and sucrose + oat beta-glucan (S+ObetaG). ObetaG and S treatments consisted of a solution of 50% ObetaG and 6% sucrose, respectively, and were administered in drinking water for 10 consecutive days. Exercise consisted of a treadmill run to fatigue performed on three consecutive days. Mice were then intranasally inoculated with a standardized dose of herpes simplex virus 1 (HSV-1) and monitored for morbidity and mortality for 21 days. Additional mice were used to determine macrophage antiviral resistance. In the exercise experiment, S, ObetaG, and S+ObetaG all reduced morbidity (P < 0.05), while only S+ObetaG reduced mortality (P < 0.05). Macrophage antiviral resistance was also increased in S, ObetaG, and S+ObetaG treatments (P < 0.05). In resting controls, S and S+ObetaG reduced morbidity and mortality (P < 0.05) and showed a trend toward increased macrophage antiviral resistance. There was no significant additive effect of S and ObetaG in either control or exercised animals. These data extend our previous work on the benefits of oat beta-glucan to show that sucrose feedings have similar effects on susceptibility to respiratory infection and macrophage antiviral resistance in both resting controls and following exercise stress.

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Inter-individual variability in immunocompetence, recovery, exercise capacity, non-training stress factors, and stress tolerance likely explains the different vulnerability of athletes to illness. Most athletes should be able to train with high loads provided their programme includes strategies devised to control the overall strain and stress. Athletes, coaches and medical personnel should be alert to periods of increased risk of illness (e.g. intensive training weeks, the taper period prior to competition, and during competition) and pay particular attention to recovery and nutritional strategies. Although exercising in environmental extremes (heat, cold, altitude) may increase the stress response to acute exercise and elevate the extent of leukocyte trafficking it does not appear to have marked effects on immune function other than a depression of cell-mediated immunity when training at altitude. The available evidence does not support the contention that athletes training and competing in cold (or hot) conditions experience a greater reduction in immune function compared with thermoneutral conditions. Nevertheless, it remains unknown if athletes who regularly train and compete in cold conditions report more frequent, severe or longer-lasting infections. Research should identify whether the airway inflammation associated with breathing large volumes of cold dry air or polluted air impairs airway defences and whether athletes (and their physicians) wrongly interpret the sore throat symptoms that accompany exercising in cold or polluted air as an infection. Elite athletes can benefit from immunonutritional support to bolster immunity during periods of physiological stress. Ensuring adequate energy, carbohydrate and protein intake and avoiding deficiencies of micronutrients are key to maintaining immune health. 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