Introduction and Purpose: Reduced physical activity causes molecular changes in skeletal muscle, leading to inflammation, apoptosis, and impaired regeneration. Tweak and its receptor Fn14 are involved in these processes. This study investigated the effects of endurance, resistance, and combined training on these genes in the soleus muscle of rats with reduced activity induced by spinal nerve ligation (SNL).

Materials and Methods: Twenty-four male Wistar rats were randomly divided into four groups: Sham-SNL, endurance, resistance, and combined training. Animals performed 6 weeks of training before SNL induction, followed by 4 weeks of SNL. Soleus muscle was extracted, and Tweak and Fn14 expression were measured by real-time PCR. Data were analyzed using one-way ANOVA and Tukey's test.

Results: Tweak expression significantly decreased in all training groups versus Sham-SNL (P < 0.05), with no differences among exercise types. Fn14 expression was significantly lower in the combined training group compared to Sham-SNL and endurance groups (P < 0.05), while other comparisons were not significant.

Conclusion: Exercise training, especially combined training, may reduce the harmful effects of reduced physical activity by modulating Tweak and Fn14 expression in the soleus muscle. These findings support the role of exercise in preventing muscle atrophy, but further studies are needed to confirm functional and protein-level effects.