Voluntary Running Attenuates Metabolic Dysfunction in Ovariectomized Low-Fit Rats

Area of Science:

• Exercise physiology
• Metabolic health
• Endocrinology

Background:

• Ovariectomy and high-fat diet (HFD) exacerbate obesity and metabolic dysfunction, particularly in individuals with low aerobic fitness.
• Exercise training is known to mitigate metabolic abnormalities, but its effectiveness after ovariectomy and HFD is not well understood.

Purpose of the Study:

• To determine if exercise training improves metabolic function in rats with low intrinsic aerobic capacity following ovariectomy and a high-fat diet.

Main Methods:

• Female rats selectively bred for low (LCR) and high (HCR) aerobic capacity were ovariectomized, fed HFD, and assigned to sedentary (SED) or exercise (EX) groups.
• Measurements included resting energy expenditure, glucose tolerance, spontaneous physical activity, body composition, metabolic markers, and skeletal muscle gene/protein expression.

Main Results:

• Exercise training reduced body weight and adiposity in LCR rats but unexpectedly increased them in HCR rats, potentially due to dietary overcompensation.
• Despite a fivefold difference in running volume, exercise equally enhanced insulin sensitivity, resting energy expenditure, and skeletal muscle mitochondrial content in both LCR and HCR rats.

Conclusions:

• Exercise training similarly improved systemic insulin sensitivity, resting energy expenditure, and skeletal muscle mitochondrial content in ovariectomized rats fed HFD, irrespective of their baseline aerobic capacity.
• These findings highlight the sustained benefits of exercise on metabolic health even under conditions of obesity and hormonal changes induced by ovariectomy.