AMSTERDAM — For patients with severe respiratory impairment, the simple act of breathing can be a struggle, making exercise seem like an insurmountable challenge. However, with the right strategies, even the most severely affected patients can participate in and greatly benefit from rehabilitation, said experts at the European Respiratory Society (ERS) International Congress 2025.

“The most important [thing] is to be aware that even in the severely impaired patients, it’s possible to implement exercise training,” José Miguel dos Santos Castro Padilha, MD, PhD, an assistant professor and rehabilitation specialist at the Nursing School of the University of Porto, Portugal, told Medscape Medical News. Physical activity, however, must be “implemented by a very well-educated, interprofessional team with the clinical experience to adapt the intervention to the features of the patient,” he said.

Deconstructing Dyspnea to Enable Exercise 

Dyspnea, or the uncomfortable feeling of shortness of breath, is a barrier to exercise for this demographic, and helping patients overcome it requires an understanding of its underlying causes, said J. Alberto Neder, MD, a respirologist and clinical physiologist at Queen’s University in Kingston, Ontario, Canada. 

Dyspnea is a mismatch between high ventilatory demand and low ventilatory capacity, which can be caused by excessive breathing, such as hyperventilation, or constrained breathing, such as mechanical restraints on breathing.

Anxiety, panic attacks, or dysfunctional breathing patterns can cause excessive breathing. It can also arise from chemical drivers, including hypoxemia, a high CO₂ flow from the periphery to the lungs, and early-onset lactic acidosis during exercise.

Strategies to manage excessive breathing focus on reducing ventilatory demand. “This involves a combination of clinical treatment and rehabilitation,” Neder explained. Techniques include desensitization to the feeling of dyspnea, anxiety control, and diaphragmatic breathing exercises to improve efficiency.

Constrained breathing, on the other hand, results from mechanical limitations. Expiratory flow limitation is a major issue, leading to progressive dynamic hyperinflation as the patient is unable to exhale fully during exertion. This “breath stacking” increases the work of breathing and exacerbates dyspnea. Interventions to improve respiratory capacity, such as bronchodilators, supplemental oxygen, and noninvasive ventilation (NIV), can be beneficial in alleviating these constraints and making dynamic exercise possible.

Optimizing Oxygen and Training Modalities 

Patients on long-term oxygen therapy need proper oxygen titration during activity, and fixed, constant-flow oxygen may not meet the increased demands of exercise, Tessa Schneeberger, a clinical exercise physiologist at Amsterdam University Medical Center, explained. “Some patients may desaturate during exercise even with their prescribed flow,” she said.

One study she presented compared fixed oxygen flows to automated demand-delivery systems with an oxygen saturation target set at 92% in patients with severe or very severe chronic obstructive pulmonary disease (COPD) and hypoxemia. She found that with the automatic system, patients immediately increased their walking time, reported significantly less dyspnea, and had significantly higher oxygen saturation at iso-time. However, 20% of patients using the demand-delivery systems experienced a decrease in blood oxygen saturation of 4% or more compared to when they used their prescribed fixed-flow oxygen. Some patients in this group experienced even more severe desaturation, with drops of 10% to 13%. That’s why, Schneeberger said, it’s important to test oxygen delivery devices during an exercise session to ensure adequate saturation is maintained.

Once oxygenation is addressed, the type of training can be adapted. Interval training, which involves alternating short bursts of activity with rest periods, is a “highly feasible option for severely impaired patients,” she explained, as it can reduce the perception of dyspnea and improve overall tolerability compared to continuous exercise.

When even interval exercise becomes too burdensome, several strategies, such as NIV, high-flow therapy, partitioning, neuromuscular electrical stimulation, and whole-body vibration, have emerged. 

Schneeberger presented a trial involving patients with COPD and chronic hypercapnic respiratory failure who were already using NIV at night. When these patients performed cycle endurance training, the group using high-pressure NIV reported significantly less dyspnea compared to the control group that used only oxygen. The patients found NIV so helpful that the majority expressed a desire to continue using it as part of their exercise routines. 

A second study focused on normocapnic patients with severe COPD who were new to NIV. When these patients used NIV during a cycle endurance test, they experienced benefits, including improved inspiratory capacity, reduced dyspnea, and an increase in their exercise endurance time. Although many patients found the assisted breathing helpful, some felt the system was too complex to handle without supervision. “Individual tryouts are essential to find the most comfortable and effective approach for each patient,” she said.

Dos Santos Castro Padilha, Neder, and Schneeberger report no relevant financial relationships.

Manuela Callari is a freelance science journalist specializing in human and planetary health. Her work has been published in The Medical Republic, Rare Disease Advisor, New Scientist, The Guardian, MIT Technology Review, and others.