Children With Fragile X Syndrome Display a Switch Towards Fast Fibres in Their Recruitment Strategy During Gait

Area of Science:

• Neurology
• Genetics
• Biophysics

Background:

• Fragile X Syndrome (FXS) is a genetic disorder resulting from FMRP protein deficiency, impacting brain development.
• FMR1 gene mutations lead to FXS, with variations like FXSFull and FXSMos influencing the phenotype.
• Previous research noted gait-related muscle activity changes in FXS children.

Purpose of the Study:

• To investigate the link between altered muscle activity during gait and motor fiber recruitment strategies in FXS.
• To compare muscle fiber recruitment in children with FXS (FXSFull and FXSMos) against healthy controls.

Main Methods:

• Gait analysis of 54 FXS children and 14 controls using motion capture and surface electromyography.
• Electromyography recorded muscle activity from Gastrocnemius lateralis, Tibialis anterior, Rectus, and Biceps femoris.
• Continuous wavelet transform analyzed signal energy distribution and Instantaneous Mean Frequency (IMNF) across frequency bands.

Main Results:

• FXS children (both FXSFull and FXSMos) displayed a different muscle fiber recruitment strategy than controls.
• A higher percentage of total muscle energy and elevated IMNF were observed in FXS children (p < 0.05).

Conclusions:

• FXS children exhibit increased recruitment of fast-twitch muscle fibers during gait.
• This altered recruitment pattern may underlie the observed fatigability and exercise intolerance in FXS.