Changes in diffusion tensor imaging (DTI) eigenvalues of skeletal muscle due to hybrid exercise training

Area of Science:

• Biomedical Engineering
• Radiology
• Exercise Physiology

Background:

• Cell membrane is considered the primary barrier to water diffusion in skeletal muscle.
• Investigating the impact of exercise training on intracellular components and their effect on water diffusion is crucial.

Purpose of the Study:

• To prospectively characterize changes in diffusion tensor imaging (DTI) eigenvalues of thigh muscles following hybrid training (HYBT) in non-alcoholic fatty liver disease (NAFLD) patients.
• To assess the effect of HYBT on muscle strength and diffusion characteristics.

Main Methods:

• Twenty-one NAFLD patients underwent 6 months of HYBT (30 min/day, twice/week).
• DTI scans of the thigh were performed pre- and post-HYBT.
• Measurements included fractional anisotropy (FA), apparent diffusion coefficient (ADC), eigenvalues (λ1, λ2, λ3), and cross-sectional area (CSA) in knee flexors and extensors.
• Paired t-tests were used for pre- and post-training comparisons.

Main Results:

• Significant increase in extensor muscle strength post-HYBT (P<0.01).
• Overall increase observed in FA, ADC, and eigenvalues.
• Significant increases in eigenvalues for both flexors (λ1, λ2) and extensors (λ1-λ3) post-HYBT (P<0.01).
• HYBT led to a significant increase in all three eigenvalues.

Conclusions:

• HYBT significantly increases water diffusion in thigh muscles of NAFLD patients.
• The observed increase in eigenvalues suggests a potential enlargement of the muscle intracellular space.
• These findings highlight the potential of HYBT to modulate muscle biophysical properties in NAFLD.