Researchers at Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Japan, report that fermented milk can prevent muscle damage associated with strenuous exercise.
Exercising increases the presence of free radicals that can damage tissues. Unaccustomed and high intensity exercise causes muscle damage known as delayed-onset muscle damage that involves protein degradation in the body. The damage occurs because of several factors, including mechanical stress, calcium accumulation, and oxidative stress.
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In one of their earlier studies, Masayo Iwasa and colleagues have shown that Lactobacillus helveticus-fermented milk prevents muscle damage induced by acute exercise in experimental animals, suggesting that fermented milk may prevent the impairment of glucose metabolism associated with muscle damage.
So, this time they conducted a trial to investigate the effect of fermented milk supplementation on glucose metabolism associated with muscle damage after acute exercise in humans.
Eighteen healthy young men aged 20 to 22 years who were not habituated to a regular exercise regimen participated in this study. They participated in three trials of the study: rest with placebo intake (rest), exercise with placebo intake (placebo), and exercise with fermented milk intake (fermented milk).
High intensity exercise included resistance exercise consisting of five sets of leg and bench presses at 70-100 percent 12 repetition maximum. Examination beverage (fermented milk or placebo) was taken before and after exercise. On the following day, respiratory metabolic performance, blood collection, and muscle soreness were assessed.
The findings were-
• Muscle soreness was significantly suppressed by the consumption of fermented milk compared with placebo.
• Serum creatine phosphokinase was significantly increased by exercise, but this increase showed a tendency of suppression after the consumption of fermented milk.
• Exercise significantly decreased the respiratory quotient, although this decrease was negated by the consumption of fermented milk. [Respiratory quotient (RQ) is a measurement of the ratio between oxygen intakes and carbon dioxide exhaled by an individual].
• Exercise significantly reduced the absorption capacity of serum oxygen radical, although this reduction was not observed with the consumption of fermented milk.
These results indicate that dietary fermented milk improves the impairment of glucose metabolism associated with exercise-induced muscle damage in healthy people.
'Previously, (studies have shown that) consumption of milk (unfermented) partially attenuates the muscle damage; therefore, the placebo trial, which used unfermented milk, may have also suppressed muscle damage to some extent. However, our results showed that fermented milk is more effective than milk,' says Wataru Aoi, one of the study authors.
'The present study suggests that small digested peptides in fermented milk may contribute to increasing the level of antioxidants in muscle. In future studies, we will attempt to detect the specific small peptides present after the consumption of fermented milk,' they concluded.