Extracellular Matrix Content and Remodeling Does Not Differ Between Higher-Responders and Lower-Responders to Resistance Training.

No significant group*time interactions or main effects of time were detected for MMP-2, MMP-9, TIMP-1, TIMP-2, Collagen-1, or Collagen-4 protein levels (p > 0.05). MMP activity and VL fascial thickness also revealed no significant group*time interactions or main effects of time (p > 0.05). A significant main effect of time (p = 0.009) and group*time interaction (p = 0.007) was detected for MMP-14. Further analysis revealed a significant difference between HR and LR prior to training (p = 0.026) along with a significant decrease from pre to post in HR (p = 0.002) CONCLUSIONS: Our data suggest that skeletal muscle ECM markers did not differentiate higher-responders versus lower-responders to resistance training. However, MMP-14 was responsive to resistance training and significantly different between response clusters prior to resistance training, and this warrants further investigation.