Understanding muscle response to exercise is critical for optimizing training strategies. This study investigated the effects of dorsiflexion and plantar flexion exercises on T2* values in the tibialis anterior (TA) and soleus (SOL) muscles and explored their relationship with muscle cross-sectional area (MCA), strength, and perceived exertion. Forty participants were divided into two exercise protocols: 30 performed dorsiflexion, 16 performed plantar flexion, and 6 completed both. T2* values were measured pre-and post-exercise using a 1.5 T MRI scanner. MCA and muscle strength were assessed via MRI and a dynamometer, while perceived exertion was measured using the Borg scale. Results showed that TA T2* values significantly increased after dorsiflexion (9.04 ± 4.21 ms), peaking 600 s post-exercise, whereas SOL T2* changes during plantar flexion were minimal (1.29 ± 1.05 ms). A significant correlation (r = 0.41, p = 0.026) was observed between T2* changes and Borg scale scores during dorsiflexion, but not with muscle strength (r = 0.08) or MCA (r = 0.35). No significant correlations were found for the SOL during plantar flexion. General linear model analysis showed a significant main effect of dorsiflexion on T2* values (p < 0.0001) and perceived exertion within the dorsiflexion protocol (p = 0.044). These findings suggest that dorsiflexion induces greater metabolic disturbances in the TA compared to plantar flexion. The results emphasize the importance of exercise-specific approaches for assessing muscle function and highlight the role of perceived exertion in evaluating muscle response.
Keywords: Exercise protocol; Magnetic resonance imaging; Perceived exertion; Skeletal muscle; T2* value.
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