Exercise-induced muscle damage: multi-parametric MRI quantitative assessment

Area of Science:

• Biomedical Engineering
• Sports Medicine
• Radiology

Background:

• Eccentric exercise can cause significant skeletal muscle damage.
• Quantitative magnetic resonance imaging (MRI) techniques offer potential for evaluating muscle injury.
• Understanding the impact of different exercise modes and timings is crucial for recovery and training.

Purpose of the Study:

• To evaluate the utility of diffusion tensor imaging (DTI), T2 mapping, and intravoxel incoherent motion (IVIM) MRI for assessing exercise-induced muscle damage.
• To compare the effects of various eccentric exercise modes on muscle damage and recovery in rats at different time points.

Main Methods:

• 174 male Sprague-Dawley rats were divided into control and four eccentric exercise groups (once-only, continuous, intermittent, once-fatigue).
• Quadriceps femoris muscles were scanned using MRI at multiple time points post-exercise (0.5h to 168h).
• DTI (apparent diffusion coefficient, fractional anisotropy), T2 mapping (T2 values), and IVIM (D, D*) parameters were measured and correlated with desmin optical density.

Main Results:

• DTI revealed decreased muscle fiber bundles post-exercise, with apparent diffusion coefficient values increasing then decreasing, and fractional anisotropy showing the opposite trend.
• T2 values were elevated in all exercise groups, peaking in the once-fatigue group.
• IVIM parameters (D and D*) were significantly higher in exercise groups compared to control within 48 hours post-exercise.

Conclusions:

• DTI, T2 mapping, and IVIM are accurate quantitative MRI methods for evaluating skeletal muscle damage and recovery from eccentric exercise.
• Continuous exercise induced the least muscle damage, whereas once-fatigue exercise caused the most significant damage.
• These findings can inform the development of physical training and athletic programs.