Acute illnesses account for up to 50% of all medical consultations at major sporting events, mostly involving the respiratory system. Management and prevention of acute illness in athletes forms a significant component of the work of Sport and Exercise Medicine (SEM) clinicians. Acute respiratory illness can be both non-infective and infective. Due to the structural and functional connection between upper and lower airways, there is a pathological continuum in this including allergy, asthma, infection and other inflammatory conditions related to pollution and chemical exposure. However, the terms ‘upper’ or ‘lower’ respiratory tract disease are still used commonly when referring to both non-infective and infective causes.

The incidence of acute respiratory infection in athletes is somehow less than that in general population. These are mostly caused by different viruses, occasionally by bacteria, and rarely by other pathogens (e.g., fungal). Like in the general population, a viral etiology accounts for >80% of all upper respiratory tract infections, e.g. rhinoviruses, non-SARS coronaviruses, influenza viruses and RS-viruses. In most of these, inflammatory mediators such as prostaglandins and bradykinins are responsible for local symptoms (rhinorrhea and nasal congestion), while cytokines are responsible for systemic symptoms (fever, chills, headache, myalgia). Incubation period and infectiousness are two pathophysiological features that have specific clinical relevance to the SEM clinician, as it informs clinical decision making when controlling viral epidemics within the teams. Endurance sports, winter seasons, training at altitude, vitamin D deficiency, long haul international travel are considered to be major risk factors in athletes. Both pathogen and host dependent symptoms typically peak within 2–3 days after onset, are self-limited and resolve by 7–10 days in athletes. Management generally includes non pharmacological treatment, immune supplements, symptomatic medicines and rarely anti-viral/antibiotics. The recommendations for return to sports are based on the severity of the symptoms, health risk based on history, clinical assessment and specific investigations, activity risk and risk tolerance.

Causes of non-infective respiratory illness in athletes can involve predominantly the upper (e.g., structural nasal obstruction, acute allergic and non-allergic rhinitis/rhino sinusitis and exercise-induced laryngeal obstruction) or the lower airways (lower airway dysfunction). Allergic rhinitis is a symptomatic IgE-mediated inflammatory mucosal nasal condition, resulting from allergen introduction in a sensitized individual specially due to increased ventilation during exercise. Rhino sinusitis is defined as acute or chronic condition in the absence of clinical symptoms and signs of infection, without evidence of allergies. The exceptions are cold air-induced rhinitis in winter athletes and chemically-induced rhinitis in swimmers, linked at least partly to the chlorine disinfection. Exercise-induced laryngeal obstruction (EILO) is caused by paradoxical inspiratory narrowing of the laryngeal structures during exercise in an otherwise normal larynx at rest which may impair exercise performance. Lower airway dysfunction (LAD) is used as an umbrella term to encompass the clinical entities like exercise-induced asthma and bronchospasm and airway hyper-responsiveness (AHR). A key strategy to prevent LAD in athletes is to reduce exposure to cold and polluted air. Team physicians need to advise a spectrum of preventive measures based on the risk factors applicable and the prevailing situations combined with the individual athlete’s profile.