Inclusion Criteria:

• - Confirmed diagnosis of SSc, determined by the treating rheumatology service either from the Rheumatology and/or Internal Medicine Service of the Specialty Hospital of the National Medical Center La Raza IMSS , based on the ACR/EULAR 2013 criteria for SSc.

• - Time of evolution of the disease indistinct.

You can be treated with any of the drugs in the spectrum of autoimmune disease treatment (immunosuppressants, steroids, biologics, etc.).

• - Diagnosis of Interstitial Lung Disease associated with SSc, confirmed by HRCT and FVC < 80% or TLC < 80% or DLCO < 80%.

Exclusion Criteria:

• - Pregnant.

• - Chest, abdominal pain, oral or facial pain that prevents using the mouthpiece or forced expiration.

• - Stress incontinence, dementia or confusion.

• - Who have contraindications for performing physical effort.

• - Oxygen dependence that does not allow its withdrawal for more than 10 minutes.

• - Recent surgeries less than 1 month in case of thorax and upper abdomen and less than three months in case of retina and middle ear surgery.

• - Belonging to vulnerable groups (homeless people, prisoners, etc.) - Failure to obtain the informed consent signature.

• - Presence of contraindication to exercise such as muscular or orthopedic injuries.

• - Who have presented disease activity data that would have required a change in pharmacological treatment in a period of less than 12 weeks prior to the start of the rehabilitation program.

Consecutive patients who attend the Rheumatology and Internal Medicine services with a confirmed diagnosis of Interstitial Lung Disease associated Systemic Sclerosis, at the Speciality Hospital from the National Medical Center La Raza IMSS, all patients who wish to participate in the study will be asked to sign the informed consent letter from the participating researchers, subsequently the anxiety and depression questionnaire will be applied to them. Goldberg, as well as the SF-36 questionnaire to evaluate quality of life and the SySQ questionnaire to evaluate functionality, to include these data in the analysis, as well as history of smoking, occupational and environmental exposures to both biomass combustion smoke and inorganic powders, these questionnaires are validated in our population and have been widely used, the data corresponding to the time of evolution of the disease, medications used, comorbidities and levels of antibodies and acute phase reactants will be collected from the clinical records. of each of the participants. All participants (T0) will undergo Forced Spirometry, Carbon Monoxide Diffusion Capacity (DLCO) and Cardiopulmonary Exercise Test. The Pulmonary Function Laboratory of the National Medical Center General Hospital has qualified and trained personnel in performing respiratory function tests, the interpretation of said results will be carried out by the main author (doctoral student) who has a high specialty in Respiratory Physiology and Pulmonary Function Laboratory. Subsequently, the patients will be sent to the Pulmonary Rehabilitation service of the La Raza National Medical Center where they will enter a supervised pulmonary rehabilitation program that consists of 36 sessions, which is equivalent to 12 weeks. At the end of this period (T1), again the respiratory function tests (spirometry, plethysmography, DLCO, arterial blood gases and Cardiopulmonary Exercise Test) as well as the Goldberg, SF-36 and SySq questionnaires. The protocol has been submitted for approval to the National Health Research Committee (CNCI). Study procedures. Every day prior to the start of the work day in the Pulmonary Function Laboratory of the National Medical Center La Raza IMSS, the cleaning and disinfection procedures of the equipment are carried out according to the manufacturer's requirements and the procedures are carried out. calibration, both for volume and flow linearity according to ATS/ERS 2005 standards for flow sensors, as well as linearity calibrations for the gas analyzer and pressure and temperature calibrations of the equipment. Prior to performing the lung function tests, anthropometric measurements will be performed as follows:

• - Height: with the patient in a standing position, height will be obtained with a wall stadiometer model 206 (Seca GMBH & Co.

, Hamburg, Germany). This measurement will be carried out by placing the heels together, close to the wall, as well as the calves, buttocks, shoulder blades and head. The head will be positioned by asking the patient to look forward, keeping the lateral canthus of the orbit horizontal in relation to the auditory meatus (Frankfort plane).

• - Weight: with the patient wearing light clothing, the weight will be obtained using a precision digital scale model 813 (Seca GMBH & Co.

, Hamburg, Germany). Goldberg Questionnaire for Anxiety and Depression The Goldberg Anxiety and Depression Scale is both a screening test, with healthcare and epidemiological uses, and an interview guide. It is a test that not only guides the diagnosis towards anxiety or depression (or both in mixed cases), but also discriminates between them and measures their respective intensities. The Goldberg Anxiety and Depression Scale contains 2 subscales with nine questions in each: anxiety subscale (questions 1-9) and depression subscale (questions 10-18). The first 4 questions of each subscale (questions 1-4) and (questions 10-13), respectively, act as a precondition to determine whether the rest of the questions should be attempted. Specifically, if a minimum of 2 questions from questions 1-4 are not answered affirmatively, the rest of the questions in the first subscale should not be answered, while in the case of the second subscale it is sufficient to answer affirmatively to one question. between questions 10-13 to be able to proceed to answer the rest of the questions. The cut-off points are 4 or more for the anxiety subscale and 2 or more for the depression subscale, with scores being higher the more serious the problem is (the maximum possible being 9 in each of the subscales). Even when the questions are very clear, the answers only admit dichotomy, so that sometimes, when coincidences of slight intensity are involved, the judgment of a specialist professional is necessary to assess the clinical significance of the answer. SF-36 Questionnaire This questionnaire contains 36 items to measure health in eight dimensions: perception of general health, physical and social functioning, limitations of function due to physical or emotional problems, health, vitality and body pain. For each dimension, items are coded, summed, and transformed into a scale from 0 (worst health) to 100 (best health). The eight dimensions can be reduced to two summary measures, a physical component score (PCS) and a mental component score (MCS). The MCID in brief form 36 (SF-36) has been estimated in patients with rheumatoid arthritis which has been estimated at 20% improvement in baseline score. SySQ Questionnaire. It is a self-administered functionality questionnaire for SSc (Systemic Sclerosis Questionnaire [SySQ]), which assesses the difficulty in carrying out activities of daily living and the intensity and frequency of the symptoms with the greatest functional impact in SSc. This instrument was originally designed in German and has been validated in Spanish by this working group. Include 3 domains concerning activities of daily living, intensity and frequency of symptoms. Three domains in 4 categories: 1) general symptoms; 2) musculoskeletal symptoms; 3) cardiopulmonary symptoms, and 4) symptoms of the digestive tract, which are the main organs affected and represent the greatest impact on the functionality of patients with Ssc. This scale includes an ability to perform an action section (0 = no difficulty, 1 = some difficulty, 2 = some difficulty, 3 = unable to do); another section describes the intensity of the symptoms (0 = no, 1 = mild, 2 = moderate, 3 = very severe), and finally there is a section on the frequency of the symptoms (0 = no, 1 = sometimes, 2 = often, 3 = always). The final score of the scale is calculated by averaging the maximum value obtained in each domain (block of questions) divided by 3 (given that there are 3 domains), and that value goes from 0 (normal functionality) to 3 (minimal functionality). The questionnaire formats will be provided by the pulmonary function laboratory staff to the study participants. Forced spirometry. Spirometry is the main test of respiratory function, it evaluates respiratory mechanics and is the standard for diagnosing bronchial obstruction. The test was performed in accordance with ATS/ERS 2005 standards. Once the patient is prepared for the test, the patient is instructed about the procedure. It is explained to him that he will be sitting (preferably in a fixed chair with arm support), with his trunk upright and his head slightly elevated; He is instructed to place a mouthpiece and a nose clip in his mouth and to perform a maximum inhalation and then an exhalation with an explosive and sustained onset. The maneuver will be carried out in a closed circuit. The patient will be asked to maintain forced expiration for at least 6 seconds until reaching a plateau of at least 1 second. The available equipment is the brand and model Jaeger Sentry Suite Ver. 2.13, IOS, Germany. Carbon monoxide diffusing capacity (DLCO) This test is necessary to evaluate gas transfer, it is necessary to complement the diagnosis and rule out interstitial damage in patients who present restriction of extrapulmonary origin. The test will be performed according to ATS/ERS 2017 standards. The patient will be seated (fixed chair with arm support), with the trunk upright and the head slightly elevated. You will be fitted with a nose clip and asked to breathe into the equipment through a sterile antibacterial mouthpiece. At the beginning, breaths were performed in tidal volume and later, based on residual functional capacity, a maximum expiration was made, until reaching a plateau of 1 second and reaching residual volume. When the residual volume was reached, the valves were activated. The patient was encouraged to perform maximum and rapid inspiration (less than 3 seconds), which reached more than 90% of his vital capacity. He must maintain an apnea for 10 seconds, taking care that there are no leaks or valsalva maneuver. The patient was instructed to make a maximum expiration, but slowly and relaxed, lasting longer than 4 seconds. The time between maneuvers was at least 4 minutes. A minimum of two efforts were completed with acceptability criteria in accordance with ATS/ERS 2017. The available equipment is the brand and model Jaeger Sentry Suite Ver. 2.13, Germany. Exercise test.

Arms

: Patients whit Systemic Sclerosis asociated Interstitial Lung Disease

Consecutive patients who attend the Rheumatology and Internal Medicine services with a confirmed diagnosis of Systemic Sclerosis associated Interstitial Lung disease, from the Medical Center, La Raza IMSS.

Interventions

Procedure: - Pulmonary Rehabilitation Program

Consecutive patients who attend with a confirmed diagnosis of Systemic Sclerosis associated Interstitial Lung disease, at the Speciality Hospital from the Medical Center La Raza IMSS. The anxiety and depression questionnaire will be applied to them. Goldberg, as well as the SF-36 questionnaire to evaluate quality of life and the SySQ questionnaire to evaluate functionality, to include these data in the analysis, these questionnaires are validated in our population and have been widely used. All participants (T0) will undergo Forced Spirometry, Carbon Monoxide Diffusion Capacity and Cardiopulmonary Exercise Test. Then they will enter a supervised pulmonary rehabilitation program that consists of 36 sessions, which is equivalent to 12 weeks. At the end of this period (T1), again the respiratory function tests (spirometry, DLCO and Cardiopulmonary Exercise Test) as well as the Goldberg, SF-36 and SySq questionnaires.