Effects Of Phytoecdysteroids On Skeletal Muscle Contractile Function And Protein Synthesis After Eccentric Muscle Damage

The objective of this study was to determine if 20-Hydroxyecdysone (20E) enhances recovery of maximal tetanic torque production and additively stimulates Akt/mTOR signaling after eccentric contractions (EC). Male mice were assigned to either the EC + placebo or EC + 20E group. In vivo isometric contractions were performed to obtain optimal electrode placement. In vivo torque frequency was assessed, 150 eccentric contractions were performed and in vivo torque frequency was administrated to assess torque production immediately post-injury to the anterior crural skeletal muscles. Upon completion of the protocols, the mice received an oral gavage of either 20E (50 mg/kg BW) in liquid diet or placebo. Mice were gavaged daily, on day 3 or 7, post-injury torque frequency was assessed and skeletal muscles were harvested and prepared for assessment of Akt/mTOR signaling via Western blot analysis. No significant differences in recovery of torque production within groups were observed at any time point or treatment. Furthermore, no significant differences were found in activation of Akt, 4E-BP1, or rpS6 intracellular signaling between treatments. These data suggest that 20E does not additively stimulate an increase of protein synthesis and enhance recovery of torque production after eccentric contraction injury.