Aerobic and Resistance Training Attenuate Differently Knee Joint Damage Caused by a High-Fat-High-Sucrose Diet in a Rat Model

Abstract

Objective: Obesity and associated low-level local systemic inflammation have been linked to an increased rate of developing knee osteoarthritis (OA). Aerobic exercise has been shown to protect the knee from obesity-induced joint damage. The aims of this study were to determine (1) if resistance training provides beneficial metabolic effects similar to those previously observed with aerobic training in rats consuming a high-fat/high-sucrose (HFS) diet and (2) if these metabolic effects mitigate knee OA in a diet-induced obesity model in rats.

Design: Twelve-week-old Sprague-Dawley rats were randomized into 4 groups: (1) a group fed an HFS diet subjected to aerobic exercise (HFS+Aer), (2) a group fed an HFS diet subjected to resistance exercise (HFS+Res), (3) a group fed an HFS diet with no exercise (HFS+Sed), and (4) a chow-fed sedentary control group (Chow+Sed). HFS+Sed animals were heavier and had greater body fat, higher levels of triglycerides and total cholesterol, and more joint damage than Chow+Sed animals.

Results: The HFS+Res group had higher body mass and body fat than Chow+Sed animals and higher OA scores than animals from the HFS+Aer group. Severe bone lesions were observed in the HFS+Sed and Chow+Sed animals at age 24 weeks, but not in the HFS+Res and HFS+Aer group animals.

Conclosion: In summary, aerobic training provided better protection against knee joint OA than resistance training in this rat model of HFS-diet-induced obesity. Exposing rats to exercise, either aerobic or resistance training, had a protective effect against the severe bone lesions observed in the nonexercised rats.

Keywords: aerobic exercise; high-fat/high-sucrose diet; knee; metabolic disease; obesity; osteoarthritis; resistance exercise.

Figure 1.

Knee joint damage represented by total knee joint OA score. Data presented as box plots showing the median and interquartile ranges and the individual values for rats fed the chow diet (Chow+Sed), animals fed the HFS diet (HFS+Sed), and animals fed the HFS diet and subjected to aerobic and resistance exercise (EXE). OA = osteoarthritis; HFS = high fat/high sucrose; Chow+Sed = chow diet with no exercise; HFS+Sed = HFS diet with no exercise intervention. ^aA significant difference compared to Chow+Sed at P < 0.05.

Figure 2.

Knee joint damage assessed using total knee joint OA scores. Data presented as box plots showing the median and interquartile ranges and the individual values for animals fed an HFS diet subjected to aerobic exercise (HFS+Aer) and animals fed an HFS diet subjected to resistance exercise training (HFS+Res). OA = osteoarthritis; HFS = high fat/high sucrose; HFS+Aer = HFS diet subjected to aerobic exercise; HFS+Res = HFS diet subjected to resistance exercise. ^aA significant difference at P < 0.05.

Figure 3.

Knee joint damage assessed using total knee joint OA scores. Data are presented as box plots showing the median and interquartile ranges and the individual values for all animals in the nonexercised/sedentary groups (SED = Chow+Sed and HFS+Sed) and all animals fed an HFS diet and subjected to resistance and aerobic exercise training (EXE). OA = osteoarthritis; HFS = high fat/high sucrose; Chow+Sed = chow diet with no exercise; HFS+Sed = HFS diet with no exercise intervention. ^aA significant difference at P < 0.05.

Figure 4.

Histological slides showing knee joint integrity. (A) Severe lesions commonly seen in the femur of rats in the nonexercised/sedentary groups (Sed = Chow+Sed and HFS+Sed). OA femur score = 33 (maximum = 36). (B) Exemplar joint showing healthy cartilage and bone of the rats subjected to aerobic or resistance exercise (EXE = HFS+Aer and HFS+Res). OA femur score = 2 (maximum = 36). The black arrow indicates a severe bone lesion and bone degeneration associated with a collapse of the adjacent cartilage. OA = osteoarthritis; HFS = high fat/high sucrose; HFS+Aer = HFS diet and subjected to aerobic exercise; HFS+Res = HFS diet and subjected to resistance exercise.