Interstitial lung diseases cause scarring and stiffness of the lungs, leading to impaired breathing and reduced quality of life. The diaphragm, the main respiratory muscle, may become weakened in these patients. Pulmonary rehabilitation is a comprehensive program that includes exercise, education, and support to improve physical capacity and overall well-being.

This study will evaluate whether an eight-week pulmonary rehabilitation program improves the diaphragmatic index (measured by ultrasound), quality of life, exercise tolerance (through functional tests), muscle strength, and dyspnea perception in patients with interstitial lung diseases.

Participants will be recruited at the Antiguo Hospital Civil de Guadalajara "Fray Antonio Alcalde" between July and December 2025. The findings will provide new insights into the impact of pulmonary rehabilitation on diaphragmatic function and contribute scientific evidence to optimize the treatment of these conditions.

This is a prospective longitudinal before-after study designed to evaluate the impact of a structured pulmonary rehabilitation program on diaphragmatic function and patient-reported outcomes in individuals with interstitial lung diseases (ILD).

A minimum of 20 patients with a confirmed diagnosis of ILD by pulmonology and imaging criteria will be enrolled. Baseline assessments will include:

Diaphragmatic index measured by ultrasound (thickness and excursion during inspiration and expiration).

Quality of life using the SF-12, or 36 or Saint George questionnaire. Exercise tolerance assessed by functional tests (4-meter gait speed, sit-to-stand, and timed up-and-go, 6 minutes walking test).

Muscle strength measured with hand dynamometry. Dyspnea evaluated using the Borg scale or mMRC.

Participants will undergo an 8-week pulmonary rehabilitation program consisting of 2-3 supervised sessions per week. The program will include:

Aerobic training tailored to individual tolerance. Muscle strengthening exercises. Breathing techniques and inspiratory muscle conditioning. Patient education and self-management strategies. All variables will be reassessed after completion of the rehabilitation program. The primary outcome is the change in diaphragmatic index. Secondary outcomes include changes in exercise tolerance, quality of life, muscle strength, and dyspnea perception.

This study will be conducted at the Antiguo Hospital Civil de Guadalajara "Fray Antonio Alcalde" between July and December 2025. The findings are expected to provide novel evidence regarding the effects of pulmonary rehabilitation on diaphragmatic function in ILD and may support the development of standardized national guidelines to optimize patient care.

Inclusion Criteria:

• Age ≥ 18 years.
• Confirmed diagnosis of interstitial lung disease (ILD) by pulmonology and imaging criteria.
• Clinically stable for at least 4 weeks prior to enrollment (no exacerbations or hospitalizations).
• Able to perform pulmonary rehabilitation and functional tests safely, as determined by medical evaluation.
• Willing and able to provide written informed consent.

Exclusion Criteria:

• Acute exacerbation of ILD or respiratory infection within the last 4 weeks.
• Severe comorbidities limiting participation (e.g., unstable cardiac disease, uncontrolled hypertension, recent myocardial infarction < 3 months).
• Advanced neuromuscular disease or musculoskeletal limitation that prevents exercise training.
• Cognitive impairment or psychiatric condition interfering with protocol adherence.
• Pregnancy or breastfeeding

The study involves a small sample size, and data are considered sensitive. Only aggregated results will be shared in publications and reports.