Interstitial lung diseases (ILD) are a highly incapacitating group of chronic respiratory diseases, leading to disabling symptoms and impaired capacity to perform activities of daily living and health-related quality of life (HRQoL). It is known that people with ILD are highly inactive and sedentary, and in a severe stage of the disease, these people spend most of the time at home, increasing dependency on others, and decrease HRQoL. Physical activity is a cost-effective intervention, which increases the HRQoL, exercise capacity and ability to perform activities of daily living in people with chronic respiratory diseases. However, few home-based physical activity programmes are available, especially in people with ILD. Thus, it is urgent to develop innovative models of PA, closer to patients and adjusted to the patients' routines, to engage and change patients' physical activity levels, enhancing HRQoL.

iLiFE might be promising as it focuses on establishing new behaviours, within selected contexts to stimulate home-based PA. Therefore, iLiFE will be developed, implemented and evaluated in people with ILD.

Interstitial lung diseases (ILD) comprise the most highly incapacitating group of chronic respiratory diseases, with significant morbidity and high mortality.

Physical activity (PA) improves HRQoL, exercise capacity and performance of activities of daily living, control the symptoms and prevent the development of further comorbidities in people with chronic respiratory diseases. However, people with ILD are highly inactive and sedentary and, as the disease progresses, these people spend most of time at home and adhere poorly to interventions, which worsens HRQoL, intensifies clinical decline and increases dependency on others.

Home-based PA programmes, integrated in patients' daily routines, may increase PA levels. Lifestyle Integrated Functional Exercise (LiFE) is a home-based PA programme, which integrates training into daily routines. This programme has shown to be effective in healthy older, however its effectiveness in people with a chronic respiratory disease population is unknown.

Therefore, this study will develop and implement a home-based PA programme, based on LiFE, in patients with advanced ILD and assess its impacts on PA levels, HRQoL and other health-related domains.

The PRIMARY AIM of this study is to assess the effects (short- and mid-term) of a home-based PA programme, based on the LiFE programme, on PA levels and HRQoL of patients with ILD, through a randomised controlled trial (RCT).

Secondary aims are to:

1. establish the feasibility of iLiFE and adherence to the intervention;
2. explore the short- and mid-term effects of the iLiFE on the impact of the disease on patients' life, symptoms, exercise tolerance, muscular strength, balance, and emotional status of patients with ILD;
3. assess the cost-benefit of the iLiFE on unscheduled healthcare resources utilisation, length of hospitalisation and number of respiratory infections.

To accomplish these aims, a feasibility study and a RCT will be conducted. iLiFE will be individually tailored to address each person's motivations and capacities, within the home context, to ensure the development and implementation of an innovative home-based PA intervention. Thus, it is expected that iLiFE will improve the PA levels of patients with ILD, enhancing HRQoL. Ultimately, this innovative research will potentially reduce health-care utilisation and costs, and finally, guide clinical and research practice, as well as policy decision makers, at a national and international level.

Task 1: Literature review

To inform the design of the intervention, the investigators will conduct a systematic review on home-based PA interventions in patients with chronic respiratory diseases according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Task 2: iLiFE-Feasibility study

A mix-methods feasibility study will be conducted to inform the recruitment procedures and components of iLiFE. Sample size will be determined by the qualitative data saturation. The investigators will use a maximum variation strategy to guide recruitment.

Ethical approval will be obtained, and data protection will be ensured by following the European regulation. Eligible patients will be identified by general practitioners or by pulmonologists, who will provide a brief explanation about the study and inform the researcher about interest participants. Then, those interested will be contacted and informed consent obtained. Participants will be eligible if are: i) ≥18 years; ii) diagnosed with stable ILD, in an advanced stage, as determined by referred doctor; iii) living at home. Participants will be excluded if: i) have a history of acute cardiac/respiratory condition on the previous month, and ii) present signs of cognitive impairment or significant cardiovascular, neurological and/or musculoskeletal disease, which may limit participation.

Data will be collected (approximately 1h) at baseline, 4-weeks (after the programme beginning) and 12-weeks (immediately after the programme). The researcher will collect:

• Sociodemographic/anthropometric and general clinical data (e.g., smoking habits, number of exacerbations, healthcare utilisation, and hospitalisation): structured questionnaire;
• PA (steps per day): accelerometry;
• HRQoL: St. George Respiratory Questionnaire;
• Impact of the disease on patients' life: COPD Assessment Test (CAT);
• Dyspnoea: Modified Medical Research Council questionnaire (mMRC) and modified Borg scale;
• Peripheral muscle strength: Handheld dynamometry and handgrip;
• Functional capacity: Time Up and Go test; Brief-Balance Evaluation Systems Test and Physical Performance Test;
• Exercise tolerance: Chester step test;
• Emotional status: Hospital Anxiety and Depression Scale;
• Activities of daily living: London Chest Activity of Daily Living;
• Self-perception of performance in everyday living: The Canadian Occupational Performance Measure (COPM);
• Fatigue: Borg modified scale and Functional Assessment of Chronic Illness Therapy - Fatigue Scale;
• Cough and sputum: Cough and Sputum Assessment questionnaire;
• Occurrence of adverse events and adherence to the interventions.

Accelerometers will be used for 1-week (8h/day) before and after the 12-weeks. The COPM will be used to develop the individualised programme for each patient based on participants' goals.

Individual semi-structured interviews will be conducted, before and after the programme, to inform about patients' preferences, perspectives, barriers and facilitators for programme participation.

iLiFE will be conducted for 12 weeks in participants' homes and will include everyday tasks to train endurance, balance, flexibility and strength. Activities will include: 1) walking and/or stair climbing to improve endurance; 2) functional-based incorporated in activities of daily living, to improve balance (work at the kitchen while standing on one leg), flexibility (stretch the upper limb when watching TV) and muscle strength (squatting instead of bending at the waist to close a drawer or to pick things up from the floor). Intensity of training will be adjusted to perceived exertion confirmed by heart rate and oxygen saturation levels. PA programme will be individualised and based on the results of the assessment.

At the start of the program, the physiotherapist will be present at all sessions, but these face-to-face visits will decrease over time using the following schedule:

• Weeks 1-4: 3 face-to-face sessions/week;
• Weeks 5-8: 2 face-to-face sessions/week and a weekly phone call;
• Weeks 9-11: 1 face-to-face session/week and a weekly phone call;
• Week 12: 2 phone calls.

Face-to-face sessions aim to adapt activities to everyday tasks, increase frequency and/or intensity, monitor progress, clarify doubts, motivate higher daily energy expenditure and manage expectations. Phone-calls aim to clarify doubts and to monitor patients' motivation/evolution, following a motivational interview. Patients will also receive a personalised manual (iLiFE manual) with activities to do in everyday tasks.

Task 3: iLiFE randomised controlled trial

Based on the findings of the literature review and feasibility study, the intervention will be refined.

A sample size calculation was computed for the primary outcome measure (daily steps). Based on a home-based pulmonary rehabilitation study conducted in patients with chronic obstructive pulmonary disease, it is anticipated that 42 participants in each group (total=84) will be needed to detect a between-group difference of 520 steps/day (power=80%, α=0.05, 2-tailed), assuming a strong correlation among paired measures (r=0.70). Since in respiratory interventions dropout rates are around 20%, 100 participants will be needed.

Patients will be randomised into experimental group (EG) and control group (CG). The EG will receive the iLiFE programme described in task 2 and, the CG will receive a leaflet with exercise and PA recommendations.

Data will be collected as described in task 2, however, follow-up assessments will be conducted at 3 and 6 months after iLiFE, to assess short- and mid-term results. In this task, all assessments will be performed by a second researcher blinded to the intervention.

Inclusion Criteria:

• clinical diagnosis of a interstitial lung disease
• clinically stable in the previous month
• ≥ 18 years old
• Living at home, assisted-home or at familiar home.

Exclusion Criteria:

• cognitive impairments
• inability to understand and co-operate
• history of neoplasic /immunologic disease or acute cardiac condition or a significant cardiac, musculoskeletal, neuromuscular or psychiatric condition
• Participating in pulmonary rehabilitation or have participated in last 6 months.

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