Effectiveness and Feasibility of a Home-based Exercise Program for Adolescents With Juvenile Idiopathic Arthritis

This study will aim to test the effectiveness and feasibility of a technology-supported home-based exercise program in adolescents with JIA. For this, adolescents (\< 18 years) with JIA will be randomized to a 12-weeks home-based exercise program or usual care (i.e., no exercise control intervention). The home-based exercise intervention will be delivered remotely using a video calling app, and participants will be instructed to perform 3 sessions of weight-bearing exercise per week. Participants will be supported by educational materials, a heart rate monitor, and through periodic contact with an exercise specialist via video and phone calls, and text messages. The study's primary outcomes will be: cardiac and vascular function and structure using ultrasound imaging, body composition (DXA), aerobic capacity, muscle strength and functional capacity. In addition to that, the feasibility, safety, acceptability, and barriers and facilitators to the intervention will also be assessed.

Juvenile idiopathic arthritis (JIA) is the most common type of arthritis in children and adolescents under the age of 16. In addition to the articular features of the disease, JIA is also characterized by multiple comorbidities, including cardiovascular manifestations. Part of the health conditions observed in adolescents with JIA may be caused by a reduced practice of physical activity. Lack of physical activity in this disease has been attributed to generic and specific barriers, such as time constraints, low motivation, limited access to specialized exercise centers, lack of specific programs for JIA patients, among others. More recently, the COVID-19 pandemic has imposed additional challenges for the engagement in physical activity in populations with chronic disease, including patients with JIA. In this scenario, home-based exercise programs supported by technology have arisen as potentially effective alternatives to upregulate physical activity levels in adolescents with JIA, which needs to be further explored. Therefore, the aim of this study will be to test the effectiveness and feasibility of a technology-supported home-based exercise program in adolescents with JIA. For this, adolescent (\< 18 years) patients with JIA will be randomized to a 12-weeks home-based exercise program or usual care (i.e., no exercise control intervention). The home-based exercise intervention will be delivered remotely using a video calling app, and participants will be instructed to perform 3 sessions of weight-bearing exercise per week. Exercise intensity and duration will be low-to-moderate in the first 4 weeks, and will progressively increase during the program. Participants will be supported by educational materials, a heart rate monitor, and by means of periodic contact with an exercise specialist via video and phone calls, and text messages. Participants in the control group will receive usual care and general instructions about physical activity. The study's primary outcome will be the cardiac and vascular structure and function assessed by vascular ultrasound imaging, body composition (DXA), aerobic capacity, muscle strength and functional capacity. Secondary outcomes will include clinical aspects of the disease, blood parameters, physical activity and sedentary behavior, food consumption, health-related quality of life, blood pressure, and cardiac autonomic function. Feasibility, safety, acceptability, and barriers and facilitators to the intervention will also be evaluated. The effects of the intervention on study outcomes will be assessed by a mixed model analysis (p \< 0.05).

Eligibility Criteria:
Inclusion Criteria:

* Patients with polyarticular or oligoarticular subtypes of juvenile idiopathic arthritis.

Exclusion Criteria:

* Cardiovascular, metabolic, pulmonary or renal diseases
* Untreat thyroid disease
* Blood pressure \> 140/80 mmHg
* Use of statin
* Use of tobacco
* Any other disease or condition that may prevent the practice of physical activity