Muscular Performance of the Elbow Flexor and Extensor Muscles in Children With Myopathies: A Case-Control Study

Area of Science:

• Pediatric Physical Therapy
• Neuromuscular Disorders
• Biomechanics

Background:

• Children with myopathies often exhibit lower limb weakness, but upper limb involvement is also significant for daily function.
• Elbow flexor and extensor muscles are crucial for activities of daily living, transfers, and mobility.
• Assessing upper limb muscle performance is vital for understanding functional limitations in pediatric myopathies.

Purpose of the Study:

• To evaluate the performance of elbow flexor and extensor muscles in children with myopathies.
• To compare muscle performance during static and dynamic contractions between children with myopathies and typically developing peers.
• To identify potential impairments in neuromuscular control affecting upper limb function.

Main Methods:

• A case-control study design matching seven children with myopathies to typically developing controls (1:2 ratio).
• Muscle performance assessment of elbow flexors (EFL) and elbow extensors (EEX) using an isokinetic dynamometer.
• Inclusion of isometric and isokinetic (120°s^-1) contractions, analyzing peak torque, total work, power, time to peak torque, acceleration, and deceleration times.

Main Results:

• Children with myopathies demonstrated significantly lower peak torque, total work, and power in both elbow muscle groups compared to controls (p < 0.05).
• No significant difference in time to peak torque was observed between the groups.
• Higher acceleration and deceleration times were noted in children with myopathies, indicating altered muscle activation and relaxation patterns (p < 0.05).

Conclusions:

• Children with myopathies exhibit significant deficits in elbow muscle performance, including reduced strength and power.
• Altered acceleration and deceleration times suggest atypical motor strategies and impaired neuromuscular control in the upper limbs.
• Isokinetic dynamometry is a valuable tool for quantifying muscle performance deficits in pediatric myopathies.