Safety of exercise versus no exercise during acute upper or lower respiratory illness: a systematic review of randomised and quasi-randomised trials

This project will answer the following research question: is it safe to exercise during acute upper or lower respiratory illness? A systematic review will be undertaken according to the following design: Population (P): Adults (aged ≥18 years) with an active acute upper respiratory illness (self-reported common cold, flu-like symptoms or viral syndromes) or lower respiratory illness (pneumonia, acute bronchitis, acute exacerbations of COPD or bronchiectasis). Intervention (I): Structured, planned, and voluntary exercise (aerobic, resistance, or combined protocols) initiated during the active/acute phase of the illness. Passive modalities (e.g., NMES, whole-body vibration) and chest physiotherapy will not be eligible. Studies will remain eligible if the exercise intervention extends beyond symptom or clinical resolution (e.g. post-hospital discharge) provided that eligible safety and clinical outcome data are captured for the acute illness or post-illness periods. Comparison (C): No exercise or usual medical care (including standard pharmacological or non-pharmacological management such as prescribed antibiotics, systemic corticosteroids, bronchodilators, mobilisation, airway clearance, breathing techniques, prescribed rest) or attention control. Outcomes (O): Acute illness period (up until symptom or clinical resolution): - adverse events - mortality - medication escalation - respiratory symptoms - viral or bacterial load - systemic inflammatory markers (white blood cell count, CRP, cytokines (IL-1, IL-6, IL-8, TNF)) - lung function (e.g., FEV1, FVC, peak expiratory flow). Post-illness follow-up (30 days): - treatment failure defined by relapse (exacerbation) or secondary infection; - fatigue Study design (S): Parallel-group trials with allocation via individual randomisation, cluster randomisation, or quasi-random method. Data synthesis: Meta-analyses will be conducted separately for upper respiratory illness and lower respiratory illness cohorts. Within each of these illness cohorts, we will perform planned sensitivity analyses of included studies based on risk of bias (low risk of bias and some concerns vs high risk of bias) and cause of illness (verified infectious causes via PCR, sputum culture, or radiology versus those using self-report or unspecified clinical definitions).