Factors Influencing Physical Activity Levels in Children With Duchenne Muscular Dystrophy: An ICF-CY-Based Study

Duchenne Muscular Dystrophy (DMD) is the most common inherited neuromuscular disorder, affecting approximately one in 3,500-5,000 live male births worldwide. It is caused by various mutations in the dystrophin gene located on Xp21.2, most commonly deletions and duplications, leading to the absence of dystrophin protein in skeletal muscle, cardiac muscle, and the central nervous system. The lack of dystrophin results in progressive muscle weakness beginning in early childhood, typically between 18 months and 3 years of age, followed by gradual loss of ambulation, increasing dependence in daily activities, and the development of serious cardiac, respiratory, and orthopedic complications later in life.

In addition to motor impairments, dystrophin deficiency in the brain has been associated with cognitive, behavioral, and psychosocial difficulties. DMD-related mutations affect multiple dystrophin isoforms that are expressed in key brain regions involved in attention, memory, executive functions, and emotional regulation. As a result, children with DMD frequently present with impairments in attention, executive functioning, learning, behavior, and emotional regulation. These non-motor manifestations further complicate disease management and have a substantial impact on participation in daily life and overall quality of life for both children and their families.

During disease progression, increasing motor limitations significantly restrict children's engagement in physical activity and increase the likelihood of adopting a sedentary lifestyle. Reduced physical activity contributes to secondary complications related to disuse, such as decreased cardiorespiratory fitness, reduced bone mineral density, increased fatigue, and further functional decline. Therefore, maintaining and supporting physical activity is considered a critical component of comprehensive care in children with DMD. However, the development of effective and sustainable physical activity-related interventions requires a thorough understanding of the factors influencing physical activity behavior in this population.

In typically developing children, physical activity levels are known to be influenced by a wide range of motor and non-motor factors, including physical function, cognitive status, sleep habits, behavioral characteristics, and family-related environmental and psychosocial factors. Although similar interactions are likely to exist in children with DMD, current evidence regarding the multidimensional determinants of physical activity in this population remains limited. In particular, the combined influence of body functions, activity limitations, participation restrictions, and family-related factors has not been sufficiently investigated within a comprehensive conceptual framework.

The International Classification of Functioning, Disability and Health - Children and Youth Version (ICF-CY), developed by the World Health Organization, provides a biopsychosocial model that enables a holistic evaluation of health by considering body functions and structures, activity, participation, and contextual factors. Using the ICF-CY framework allows for the systematic examination of the dynamic interactions between individual and environmental factors that shape physical activity behavior in children with chronic health conditions.

Therefore, the primary aim of this study is to identify the factors affecting physical activity levels in children with Duchenne Muscular Dystrophy within the ICF-CY framework. Specifically, the study will evaluate the influence of posture, functional capacity, ambulatory status, balance, fatigue, gait, and other musculoskeletal parameters, as well as cognitive status, sleep habits and sleep quality, fear of falling, behavioral characteristics, and motivation on children's physical activity levels. In addition, family-related factors-including caregiver sleep quality, parenting style, perceptions of physical activity, stress level, attitudes and perceptions toward daily life events, and perceived disease impact-will be examined to determine their contribution to physical activity behavior.

By adopting a comprehensive ICF-CY-based approach, this study aims to clarify the relative contribution and magnitude of individual, environmental, and psychosocial factors influencing physical activity levels in children with DMD. The findings are expected to provide clinically relevant insights that may guide the development of targeted, family-centered, and multidimensional interventions aimed at maintaining or enhancing physical activity and improving long-term health outcomes and quality of life in children with Duchenne Muscular Dystrophy.