Circulating Matrix Metalloproteinase Activity and Functional Capacity in Individuals Undergoing Hemodialysis: Exploratory Findings from a Resistance Training Trial

Abstract Purpose To investigate the effects of 24 weeks of resistance training (RT) on pro- and active matrix metalloproteinases (MMPs) and their association with functional performance in end-stage kidney disease (ESKD) patients undergoing hemodialysis. Methods Forty-two ESKD patients (mean age: 65 ± 4 years; dry body mass: 71 ± 16 kg; body mass index: 25 ± 3 kg/m 2 ) were randomized into two groups: the control (CTL, n = 20) and RT group ( n = 22). RT was comprised three times per week for 24 weeks. Plasma MMP-2 and MMP-9 activity were assessed by zymography. Functional and body-composition outcomes included handgrip strength, fat-free mass (FFM), 5-min walking test, and the Timed Up and Go (TUG) test. Results Using bioinformatics tools, we found that MMP-2 gene expression in PBMCs was decreased in ESKD patients undergoing hemodialysis. At post-intervention, RT displayed a higher active MMP-2 activity, while MMP-9 did not change. After baseline adjustment, the estimated effect of RT on active MMP-2 was attenuated, whereas active MMP-9 showed a lower adjusted response in the RT group. Active MMP-2 activity was positively associated with handgrip strength, FFM ( P < 0.05), and negatively correlated with TUG test ( P < 0.05). Conclusion RT improved functional outcomes and the complex effects of RT on MMPs should be thoroughly investigated in future experimental and clinical studies.