Eccentric And Concentric Resistance Training Alterations In Muscle Z-line Proteins

Abstract

Few studies are available on the alterations of resistance training on muscle Z-lines. Thus, it is of great importance to understand long time effects of resistance training on the mechano-stability and mechano response on muscle Z-lines proteins. PURPOSE: The present study was conducted to ascertain how Z-lines proteins (myopdin/SYNPO 2 and α-actinin) are altered by eccentric and concentric resistance training leading to possible alterations in mechano-stability and mechano-response. METHODS: Ten (10) healthy male subjects with age (25.3 ± 1.4 years), height (1.87 ± 0.09 m), weight (73.2 ± 11.6 kg) and BMI (24.4 ± 3.3 kg·m-2) were grouped into eccentric resistance (n= 5) and concentric resistance (n=5) training. Subjects underwent twelve (12) weeks of resistance training intervention on the dominate leg. Muscle biopsies were taken in five time points (T0,T1,T2,T3,T4) on the forelimb of the vastus lateralis muscle and immunohistochemistry double staining protocol were implemented. Images were taken using confocal laser scanning microscope and protein distribution was morphometrically analysed by line scanning to find-out the alterations of myopodin/SYNPO2 and α-actinin on muscle Z- lines. Paired student’s t-test was used for analysis to compare a given time point to the basal value (T0), whilst an unpaired student’s t-test was used for between groups analysis. RESULTS: We observed a significant value (0.44 ± 0.07, p < 0.007) for between group (eccentric and concentric) for myopodin/SYNPO 2 for time (T4), as well as significant value (0.50 ± 0.25, p < 0.034) between time (T0 and T4) for eccentric training on myopodin/SYNPO 2. Also, we observed a significant value (0.69 ± 0.09, p < 0.013) between group (eccentric and concentric) for Z-line for time (T3). The results show that myopodin/SYNPO 2 is more restricted or distributed in the Z-line region. Also, it could be that the compression of Z-line at time (T3) led to a higher signal at the reducing ratio of α-actinin for both eccentric and concentric training, which depends on the time and type of training in a dose-response manner. CONCLUSION: Long-term exposure of resistance training, especially eccentric type, affects Z-lines (myopodin/SYNPO 2 and α-actinin) proteins functional architecture and structure against myofibrillar stress.