Resistance training may not only help to build muscle in older people, it may also be warding off type 2 diabetes, a new study demonstrates. Thirty-six men and women in their early 60s experienced significant improvements in glucose tolerance after a 12-week resistance-training regimen, Dr. Wayne W. Campbell of Purdue University in West Lafayette, Indiana, and his colleagues found.
"The idea that you could actually improve your glucose tolerance by about 25 percent to 30 percent with 12 weeks of strength exercise without having any weight loss, which is a typical therapy for this, is very encouraging," states Campbell.
People lose their ability to metabolize sugar effectively as they age, even if they’re otherwise healthy, Campbell and his team note in their report in the American Journal of Clinical Nutrition. And the weight gain that frequently accompanies aging worsens glucose tolerance and compounds diabetes risk. One in five Americans older than 60 years has type 2 diabetes, they add.
There is evidence that resistance training can improve glucose tolerance, while adequate protein levels are necessary for resistance trainers and may even improve changes in body composition and glucose tolerance that come with weightlifting, the researchers note.
To investigate how resistance exercise and dietary protein affect metabolism, the researchers had the study participants work out on resistance machines three times a week for 12 weeks. Each workout session lasted for about an hour and 15 minutes, and included 8 exercises.
Half of the study participants consumed 0.9 grams of protein for each kilogram of body weight per day (low-protein group); the other half consumed 1.2 grams of protein per kilogram (high protein group). The current recommended amount of daily protein is 0.8 grams per kilogram of body weight.
Men and women in the high-protein and the low-protein groups experienced small but significant reductions in total cholesterol and in low-density lipoprotein, the "bad" cholesterol. The level of reduction was similar in both groups.
Changes were similar to what would have occurred with short-term weight loss. And both groups also experienced similar increases in lean body mass and reductions in fat mass.
However, the most dramatic effect was on glucose tolerance, Campbell said, with both groups showing a "profound" improvement in glucose tolerance after the 3-month training program.
The findings are especially significant, the researcher added, because the study participants were at risk of developing type 2 diabetes because of their age and, in some cases, their weight.
"Another five or ten years from now, if they follow the usual paths, they’re going to become heavier and move into the clearly overweight category," he explained.
Campbell emphasized that all of the study participants were getting adequate amounts of high-quality protein, and urged anyone considering beginning a weight resistance program to do the same.
American Journal of Clinical Nutrition, April 2007.
DID YOU KNOW:
A New Risk Factor for Diabetes in Men? Men with testosterone levels in the low-normal range appear to be more likely to develop diabetes than those with higher levels, according to a national study. Senior study author Elizabeth A. Platz, SCD, MPH, and colleagues’ analyzed data on 1,413 men age 20 and older. Men in the lowest tertile of free testosterone were four times more likely to have prevalent diabetes when compared with men in the highest tertile. The association of low free testosterone persisted even after men with clinically low total and/or free testosterone levels were excluded, suggesting that the findings were not entirely driven by hypogonadal men. After accounting for the effect of obesity, low testosterone levels still appeared to be an important risk factor for diabetes. The study team concluded that androgens may directly influence glucose metabolism and the development of insulin resistance. The study group reported that low testosterone is a common finding among men with diabetes and may lead to other clinical problems.
The study was published in the February 2007 issue of Diabetes Care.
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