Treadmill running induces remodeling of the infrapatellar fat pad in an intensity-dependent manner

Abstract Objective To investigate the response of infrapatellar fat pad (IFP) to running at different intensities and further explore underlying mechanisms these responses under running-induced loadings. Methods Animals were randomly assigned into sedentary (SED), low-intensity (LIR), medium-intensity (MIR), high-intensity (HIR) groups. The rats in LIR, MIR, HIR groups subjected an 8-week treadmill protocol. In each group, IFP was examined baseline 8th week perform histomorphology, immunohistochemistry, mRNA expression analyses. Results Compared with LIR for 8 weeks led a substantial increase surface cellularity (1.67 ± 1.15), fibrosis (1.29 0.36), vascularity (33.31 8.43) but did not inflammation or M1 macrophage polarization. Low-to-medium-intensity resulted unchanged decreased fibrosis, vascularity, compared those SED group. Furthermore, serum leptin visfatin levels significantly lower MIR than group ( P < 0.05). Conclusion effect on remodeling intensity dependent. contrast increased IFP. HIR-induced probably due mechanical stress, rather pathological proinflammatory M1/M2