Is exercise beneficial during an active illness, such as a cold or flu, or conditions like chronic obstructive pulmonary disease (COPD) or heart failure?

Exercise During Active Illness: A Context-Dependent Approach

For acute infectious illnesses like colds or flu, exercise at reduced intensity is generally safe when symptoms are "above the neck" (runny nose, nasal congestion, mild sore throat), but exercise should be avoided when symptoms are systemic or "below the neck" (fever, muscle aches, productive cough, chest congestion). 1

Acute Infectious Illness (Cold/Flu)

Safe to Exercise (Reduced Intensity)

• Solo exercise at reduced intensity is generally safe for patients whose symptoms are confined above the neck 1
• This includes mild upper respiratory symptoms without systemic involvement 1

Avoid Exercise Completely

• Physical activity may worsen the condition when systemic symptoms are present 1
• Exercise can result in impaired performance during acute illness 1
• Risk of infecting others in group settings 1

Critical Pitfall: Many active individuals are reluctant to interrupt training schedules, but continuing high-intensity exercise during systemic illness can prolong recovery and potentially lead to more serious complications like myocarditis.

Chronic Obstructive Pulmonary Disease (COPD)

Exercise training is strongly recommended during stable COPD and provides substantial benefits even during active disease management. 2

Exercise Prescription for COPD

• Minimum 20 sessions, at least three times per week, are required to achieve physiologic benefits 2
• Both endurance and strength training should be utilized, as the combination produces multiple beneficial effects 2
• High-intensity exercise produces greater physiologic benefit and should be encouraged when tolerable 2

Interval vs. Continuous Training

• For patients with very severe COPD, interval training is associated with fewer symptoms of dyspnea during exercise and fewer unintended breaks 2
• Both continuous and interval training lead to comparable improvements in exercise capacity and health-related quality of life 2
• Interval training allows patients to achieve significantly lower metabolic and ventilatory stress with lower rates of dynamic hyperinflation 2

Specific Benefits in COPD

• Endurance training improves peripheral muscle function 2
• Training reduces the proportion of anaerobic fast-twitch (type IIb) muscle fibers, yielding a higher percentage of aerobic slow-twitch (type I) muscle fibers 2
• Benefits are comparable across COPD GOLD stages II, III, and IV 2

Chronic Heart Failure

Exercise training is strongly recommended for stable chronic heart failure patients in NYHA class II or III, but only after careful cardiac evaluation. 2

Eligibility Criteria

• All patients must have stable chronic heart failure 2
• NYHA class II or III patients are eligible 2
• Carefully selected NYHA class IV patients free of dyspnea at rest may participate with intensive supervision 2

Absolute Contraindications

• Patients with exercise-induced serious ventricular arrhythmias should not exercise until further evaluation 2
• Obstructive valvular disease, especially aortic stenosis 2
• Active myocarditis (viral or autoimmune) 2
• Unstable heart failure 2

Pre-Exercise Evaluation Required

• Cardiopulmonary exercise test 2
• Blood test for basic chemistries and electrolytes 2
• Evaluation for exercise-induced angina, silent ischemia, marked hypotension, and atrial arrhythmias 2
• Assessment for non-cardiac problems limiting exercise (anemia, reversible airway disease, peripheral vascular disease) 2

Exercise Modality for Heart Failure

• Cycle ergometer training is the most favorable type of aerobic exercise for chronic heart failure patients 2
• Allows exercising at very low workloads with exact reproducibility 2
• Enables continuous monitoring of heart rate, rhythm, and blood pressure 2
• Interval training produces more pronounced effects on exercise capacity than steady-state training, particularly in patients with very low baseline aerobic capacity 2

Specific Benefits in Heart Failure

• Exercise training reduces sympathetic and renin-angiotensin system activity 2, 3
• Improves endothelium dysfunction and reduces peripheral vascular resistance 2
• Partially corrects skeletal muscle abnormalities 2
• Reduces ventilatory abnormalities and decreases perceived dyspnea 2
• Improves noradrenaline spillover, heart rate variability, and heart rate responses during exercise 2, 3

Critical Pitfall: Swimming should be avoided in chronic heart failure patients with diastolic and systolic dysfunction, as head-up immersion causes hydrostatic volume shift that increases left ventricular volume loading and pulmonary capillary wedge pressure 2

General Principles Across Chronic Diseases

• Regular physical exercise acts as a highly efficient drug and should be used in many diseases 4
• Physical activity is an evidence-based component of prevention and therapy for heart, cardiovascular and lung diseases, diabetes mellitus, renal disease, and cancer 4
• Moving more and sitting less benefits nearly everyone, with individuals performing the least physical activity benefiting most from even modest increases 5
• Both aerobic and muscle-strengthening physical activity are beneficial 5