Serum but not exhaled breath condensate periostin level is increased in competitive athletes

Physical exercise, immune response, and susceptibility to infections-current knowledge and growing research areas

This review presents state-of-the-art knowledge and identifies knowledge gaps for future research in the area of exercise-associated modifications of infection susceptibility. Regular moderate-intensity exercise is believed to have beneficial effects on immune health through lowering inflammation intensity and reducing susceptibility to respiratory infections. However, strenuous exercise, as performed by professional athletes, may promote infection: in about half of athletes presenting respiratory symptoms, no causative pathogen can be identified. Acute bouts of exercise enhance the release of pro-inflammatory mediators, which may induce infection-like respiratory symptoms. Relatively few studies have assessed the influence of regularly repeated exercise on the immune response and systemic inflammation compared to the effects of acute exercise. Additionally, ambient and environmental conditions may modify the systemic inflammatory response and infection susceptibility, particularly in outdoor athletes. Both acute and chronic regular exercise influence humoral and cellular immune response mechanisms, resulting in decreased specific and non-specific response in competitive athletes. The most promising areas of further research in exercise immunology include detailed immunological characterization of infection-prone and infection-resistant athletes, examining the efficacy of nutritional and pharmaceutical interventions as countermeasures to infection symptoms, and determining the influence of various exercise loads on susceptibility to infections with respiratory viruses, including SARS-CoV-2. By establishing a uniform definition of an "elite athlete," it will be possible to make a comparable and straightforward interpretation of data from different studies and settings.

Let research leave you breathless, not physical exercise!

Regular physical activity is strongly recommended by healthcare systems worldwide and evidence-based guidelines and is one of the most effective approaches for preventing chronic inflammatory diseases and maintaining health status [1]. Indeed, extensive evidence exists on the beneficial effect of physical training and rehabilitation programmes in asthma [2]. Physical activity has been shown to improve quality of life, exercise capacity, pulmonary function and symptoms, as well as reduce airway inflammation and bronchial responsiveness in patients with asthma [3–5]. However, intense physical exercise may trigger airway narrowing by imposing a high demand on the respiratory system, requiring subjects to ventilate primarily through the mouth and by-pass the nasal filter, with a subsequent increased pulmonary exposure to inhalant allergens, pollutants, irritants and adverse (i.e. cold, dry) environmental conditions [6]. Such airway narrowing, which transiently occurs as a result of exercise, is defined as exercise-induced bronchoconstriction (EIB) [7]. Interestingly, in a 5-year prospective study, subjects who stopped training experienced an attenuation, or in some circumstances disappearance, of EIB, whereas bronchial responsiveness, exercise-induced respiratory symptoms and eosinophilic airway inflammation increased amongst those who continued strenuous physical exercise, regardless of the pharmacological treatment strategies [8]. Put into context, ongoing intense training appears to be a causative, and not just a concomitant, factor of airway inflammation and narrowing.

Proper endotyping of EIB and precision medicine strategies would allow subjects to fully profit from the very beneficial effects of exercise, without incurring health risks or affecting performanceshttp://ow.ly/spjT30irzjX