Aging processes are partly due to cellular rusting. Aggressive molecules – free radicals – that are released when the immune system eliminates intruders and when cells generate energy damage cell structure. It's called oxidative stress. American cancer researchers discovered that you can reduce oxidative stress by 15 percent by taking 45 minutes of daily exercise at a level that causes your maximal oxygen uptake to increase.
The researchers, who worked for the American Cancer Society, did an experiment involving 173 women. The average age of the women was 60, their average BMI was 30 and they were not physically active.
Half of the women did stretching exercises every day for a year. This was the control group.
The other half did a 45-minute aerobic training session five times a week. The women went to a gym three times a week and trained at home on the other days. They wore a heart rate monitor so that they could keep their exercise constant at 60-75 percent of their maximal heart rate. At that intensity the women could just about continue a conversation, or not quite.
Before the programmes started and at the end of the year the researchers measured the concentration of F2-isoprostanes in the women's blood. F2-isprostanes are formed when free radicals damage fatty acids. Concentration levels of these are an indicator of oxidative stress.
In the control group the concentration level of F2-isoprostanes increased by 3.3 percent; in the training group the concentration level decreased by 6.2 percent.
The decrease in oxidative stress was only statistically significant in the women whose maximal oxygen uptake [VS2max] had increased considerably. In the women whose VO2max had increased by more than 15 percent their concentration of F2-isoprostanes decreased by 14.1 percent.
Change in body composition was also a factor. In the women whose waist measurement went down by more than 3 cm, their concentration of F2-isoprostanes went down by 16.4 percent.
The effect of the decrease in waist measurement was not quite statistically significant.
The researchers suspect that physical exercise generates free radicals, and as a result the body produces more endogenous antioxidants. This last effect is so strong that the net health effect of physical exercise is positive.
Med Sci Sports Exerc. 2010 Aug;42(8):1448-53.