Intensity-Dependent Effect of Treadmill Running on Knee Articular Cartilage in a Rat Model

Guo-Xin Ni,Sheng-Yao Liu,Zhe Li,Yue-Zhu Zhou,Lei Lei,Li-Qiong Zhan

doi:10.1155/2013/172392

Abstract

Objective. To understand the changes of femoral cartilage in response to treadmill running with different intensities in the hope of differentiating “moderate” and “strenuous” running in a rat model. Method. A total of 24 male Wistar rats were randomly assigned into groups of sedentary (SED), low-intensity running (LIR), medium-intensity running (MIR), and high-intensity running (HIR). Rats in LIR, MIR, and HIR groups underwent 8 weeks' treadmill running programs. After sacrificed, femoral condyles were collected to take histomorphometric analysis and immunohistochemistry for collagen II. Results. Gross and histological observation showed osteoarthritic changes in group HIR. In comparison to SED group, there was significant increase in cartilage thickness, number of chondrocytes, and GAG content in groups LIR and MIR. Conversely, decrease in cartilage thickness, chondrocyte number, and GAG content was found in rats of HIR group, without significant difference though. In addition, in comparison to SED group, HIR group exhibited disorganization of collagen fibril and significantly lower content of collagen type II. Conclusion. An intensity-dependent effect was suggested on the articular cartilage. Our results also demonstrated that running with low-to-medium intensity applied in the present study should be regarded as “moderate” running, whereas high-intensity running as “strenuous” running.

Highlights

Osteoarthritis (OA) is a progressive degenerate joint disease that affects the structural and functional integrity of joint tissues, which is mainly characterized by cartilage degradation
Similar appearance of the cartilage was observed in groups low-intensity running (LIR) (Figure 1(b)) and medium-intensity running (MIR) (Figure 1(c))
Histomorphometric analyses were taken on hematoxylin eosin (HE)-stained sections in four groups to obtain the cartilage thickness, chondrocyte number, and Glycosaminoglycans HE (GAG) content (Table 1)

Summary

Introduction

Osteoarthritis (OA) is a progressive degenerate joint disease that affects the structural and functional integrity of joint tissues, which is mainly characterized by cartilage degradation. It is generally agreed that reduced loading has deleterious effects on articular cartilage [2]. A certain amount of joint loading is needed to maintain normal cartilage properties. Regular exercise is considered an integral component of a healthy lifestyle; its effect on articular cartilage remains a subject of debate and speculation, as does the relationship of exercise to the development of OA [3]. One of the most common weight-bearing activities, for example, its effect on the cartilage of knee joint appears conflicting. Findings from some studies using animal models suggested that running exercise may be beneficial to the cartilage health [4, 5], while others demonstrated deleterious effect [6,7,8]. “Strenuous” running is regarded as a reliable OA animal model [8]

Methods

Results

Discussion

Conclusion