Duchenne Muscular Dystrophy: Understanding, Managing, and Improving Function

Duchenne Muscular Dystrophy (DMD) is a progressive neuromuscular condition that primarily affects muscle strength, movement, and overall physical function. Although there is currently no cure for DMD, early intervention, exercise management, and multidisciplinary care can significantly improve quality of life, maintain independence, and slow functional decline. Accredited Exercise Physiologists play an important role in supporting safe physical activity, strength maintenance, mobility, and participation across all stages of the condition.

DMD is a genetic disorder caused by mutations in the dystrophin gene, resulting in the absence of dystrophin protein, which is essential for protecting muscle fibres. Without dystrophin, muscles progressively weaken and deteriorate over time.

The condition primarily affects boys and typically presents in early childhood, although symptom severity and progression can vary between individuals.

These impairments can affect:

• Functional tasks such as walking, climbing stairs, standing, and transfers
• Muscle strength and endurance
• Balance and coordination
• Respiratory and cardiac function
• Participation in school, recreation, and daily activities

What is Duchenne Muscular Dystrophy?

DMD is the most common form of muscular dystrophy in children and is classified as an X-linked recessive disorder.

As muscle damage progresses, individuals may experience increasing difficulty with mobility and physical function. Over time, weakness can also affect respiratory muscles and the heart.

Common Signs and Symptoms

• Delayed motor milestones
• Frequent falls and difficulty running
• Difficulty climbing stairs
• Walking on toes
• Enlarged calf muscles (pseudohypertrophy)
• Fatigue and reduced endurance
• Progressive muscle weakness, particularly in the hips and legs
• Difficulty rising from the floor (Gowers’ sign)
• Loss of independent walking in later stages
• Respiratory complications and reduced lung function
• Cardiomyopathy and cardiac complications

Causes and Risk Factors

DMD is caused by inherited or spontaneous mutations in the dystrophin gene.

Non-modifiable factors include:

• Male sex
• Family history of muscular dystrophy
• Genetic mutation inheritance

Unlike many chronic conditions, lifestyle factors do not cause DMD. However, appropriate management can strongly influence functional outcomes and quality of life.

How Exercise Helps

Exercise is an important component of DMD management when carefully prescribed and monitored. While excessive or high-intensity exercise may contribute to muscle damage, appropriately tailored physical activity can help maintain mobility, function, and participation.

Exercise interventions may help:

• Maintain muscle strength and joint mobility
• Reduce contracture development
• Improve balance and functional capacity
• Support cardiovascular and respiratory health
• Reduce deconditioning and physical inactivity
• Improve participation in school, recreation, and daily activities
• Enhance psychological wellbeing and quality of life

Low-to-moderate intensity exercise, stretching, aquatic therapy, and functional movement training are commonly recommended.

From an exercise physiology perspective, programs should be individualised, closely monitored, and adapted as the condition progresses.

What Does Research Say?

Exercise & Functional Capacity

Jansen et al., 2013 (Systematic Review):

• Gentle, submaximal exercise may help preserve functional ability without accelerating muscle damage
• Stretching and mobility programs assist in reducing contractures and maintaining movement

Markert et al., 2011:

• Low-intensity physical activity may improve endurance and participation in daily activities
• Overexertion and eccentric loading should be avoided due to increased risk of muscle fibre damage

Respiratory & Cardiac Management

• Respiratory training and assisted ventilation improve quality of life and longevity
• Early cardiac monitoring and management are essential due to increased risk of cardiomyopathy

Multidisciplinary Rehabilitation

• Combined physiotherapy, exercise physiology, respiratory care, and medical management produce the best functional outcomes
• Early intervention improves long-term participation and independence

Key Takeaways

• DMD causes progressive muscle weakness and reduced physical function
• Individualised exercise can help maintain mobility, flexibility, and independence
• Low-to-moderate intensity activity is safest and most effective
• Respiratory and cardiac management are essential components of care
• Multidisciplinary rehabilitation improves quality of life and long-term outcomes

The Importance of a Holistic Approach

A comprehensive management approach integrating exercise, respiratory care, physiotherapy, medical treatment, and psychosocial support provides the most effective outcomes for individuals with DMD.

• Targets muscle weakness, mobility limitations, and fatigue
• Maintains joint range of motion and functional capacity
• Supports respiratory and cardiovascular health
• Enhances participation in school, community, and recreation
• Promotes independence and quality of life across all stages of the condition

From an exercise physiology perspective, carefully prescribed physical activity plays a vital role in maintaining function, reducing secondary complications, and supporting long-term wellbeing in individuals living with Duchenne Muscular Dystrophy.