PAX7 and MyoD Proteins Expression in Response to Eccentric and Concentric Resistance Exercise in Active Young Men

Objective: Satellite cells play an important role in muscle regeneration, which this process can be affected by differentgenes including PAX7 and MyoD. Exercise training known as an important strategy for mediating the satellite cell’sfunction. Therefore, the main purpose of the present study is to investigate the changes in PAX7 and MyoD proteinexpression in response to eccentric and concentric resistance exercise in healthy young men.Materials and Methods: In this semi-experimental and cross-sectional study, 10 healthy men (age range 18-30 yearsold) participated. They were randomly divided into two equal groups (n=5) to perform one of two high-intensity eccentricor concentric knee extensions muscle contraction protocols. The contractions included a maximum of 12 sets of 10repetitions, with a 30 second rest time interval between sets. PAX7 and MyoD protein expression was assessed usingImmunohistochemistry analysis from the Vastus Lateralis muscle needle biopsy samples that have been taken 24hours before and 3 to 4 hours after the end of the exercise protocol.Results: We observed that the PAX7 protein expression level increased significantly after eccentric (47.75%) andconcentric (39.21%) (P=0.01) intervention. While, the MyoD protein expression level reduced (38.14%) significantlyfollowing acute eccentric resistance exercise (P=0.01).Conclusion: It seems that eccentric or concentric muscular contraction modulates the expression of PAX7 and MyoDprotein expression in the skeletal muscle, with further effects observed in eccentric resistance exercise.