Regular Exercise Seen to Partly Reverse Mitochondrial Damage Tied to Poor Diet in Animal Study

Regular physical exercise helped to prevent mitochondria dysfunction in animals, researchers reported, emphasizing the importance of activities that work skeletal muscles in maintaining metabolic homeostasis or equilibrium.

Although the study, which was published in the scientific journal PLOS One, describes healthy mitochondria, it furthers the understanding of the function of healthy mitochondria and, by extension, the causes and possible ways of treating mitochondrial disease. The study is titled, “Physical activity prevents alterations in mitochondrial ultrastructure and glucometabolic parameters in a high-sugar diet model.”

Researchers led by Dr. Renata Guerra-Sá of Universidade Federal de Ouro Preto, in Brazil, divided male Wistar rats into two groups, and fed one a normal diet and the other a high-sugar diet of equal calories. A number of rats in both diet groups were then put through 60-minute swimming exercises five days a week, for either four or eight weeks. At the end of the experiment, the researchers analyzed the blood, fat tissues, and skeletal muscles of the animals.

Animals fed a high-sugar diet were found to have greater body weight after eight weeks, increased fat pads (masses of closely packed fat cells surrounded by fibrous tissue), and a higher body adipose index (a measure similar to BMI but that measures the amount of body fat). These rats also showed glucose intolerance and insulin resistance, both signs of diabetes.

When the scientists analyzed the animals’ muscle tissue, they saw that the high-sugar diet also changed the structure of the rats’ mitochondria. A decrease was also seen in the activity of a mitochondrial enzyme called superoxide dismutase, an important antioxidant that protects against cell death caused by oxidative stress. And an increase was observed in protein carbonylation, which is a major hallmark of oxidative damage.

But when the researchers looked at high-sugar diet animals put through regular swimming exercises, they saw a partial reversal in the changes caused by the diet. Specifically, both alterations to the shape of muscle mitochondria and insulin resistance were prevented.

“Our results suggested a protective effect of regular physical activity in obese animals fed a HSD [high-sugar diet], preventing mitochondrial dysfunction and IR [ insulin resistance],” the team concluded.  “We observed an increase in mitochondrial density after an 8-week period of regular physical activity, which is consistent to the role of exercise inducing mitochondrial biogenesis [a process essential to cellular energy]. These results corroborate the idea that regular physical activity increases total mitochondria.”