Genes may thwart seniors' exercise gains. Keeping strong and physically fit is crucial to maintaining independence among the elderly. Exercise has repeatedly been shown to reduce or slow age-related declines in physical function and is a widely recommended for seniors, but the way that older people respond to exercise varies widely.
The full study, "Genetic Influence on Exercise-Induced Changes in Physical function among mobility-limited older adults" is published in Physiological Genomics. The new study examines the ACE I/D gene and whether its variations—the ID, DD, and II genotypes—impact some seniors' ability to fully reap the benefits of exercise. Physiology is the study of how molecules, cells, tissues, and organs function in health and disease. Authors are Thomas W. Buford et al.
Researchers followed 424 sedentary, mobility-limited seniors aged 70-89 for a year
Participants were randomly placed in a group that focused on either health education or physical activity. The health education group received ongoing presentations on eating right, how to properly use medication, and other information on maintaining a healthy lifestyle, but did not perform exercise as part of the study.
Seniors in the physical activity group were taught a variety of strength, for example, squats and leg raises, balance exercises, and a walking program that they were encouraged to perform both in a group setting and at home, according to the March 14, 2014 news release, "Genes may thwart seniors' exercise gains." Should seniors exercise a little daily to keep in shape? Or do their genes control their walking speed at different ages or with different health conditions regarding walking mobility?
The researchers measured changes in walking speed and participants' ability to perform other tasks such as getting up from a chair
They found that the physical activity intervention led to greater improvements walking speed among ID and DD genotype carriers (29.9% and 13.7% respectively). However, among II genotype carriers, health education alone led to more improvements in walking speed than physical activity intervention (20% vs. 18.5%). II carriers in the physical activity group also experienced smaller gains in lower body performance than those in the health education group.
These findings suggest that the ACE I/D genotype may be a significant factor in how well seniors respond to exercise. This insight could be used to develop more effective, individualized, and senior-friendly exercise recommendations for improving physical function and preventing in disability.
Older adults: Build muscle and you'll live longer
New University of California - Los Angeles (UCLA) research suggests that the more muscle mass older Americans have, the less likely they are to die prematurely. The findings add to the growing evidence that overall body composition — and not the widely used body mass index, or BMI — is a better predictor of all-cause mortality. You can check out the abstract of the study, "Muscle Mass Index as a Predictor of Longevity in Older-Adults." The study, published in the American Journal of Medicine, is the culmination of previous UCLA research led by Dr. Preethi Srikanthan, an assistant clinical professor in the endocrinology division at the David Geffen School of Medicine at UCLA, that found that building muscle mass is important in decreasing metabolic risk.
"As there is no gold-standard measure of body composition, several studies have addressed this question using different measurement techniques and have obtained different results," Srikanthan says, according to the March 14, 2014 news release, Older adults: Build muscle and you'll live longer. "So many studies on the mortality impact of obesity focus on BMI. Our study indicates that clinicians need to be focusing on ways to improve body composition, rather than on BMI alone, when counseling older adults on preventative health behaviors."
The researchers analyzed data collected by the National Health and Nutrition Examination Survey (NHANES) III, conducted between 1988 and 1994. They focused on a group of 3,659 individuals that included men who were 55 or older and women who were 65 or older at the time of the survey. The authors then determined how many of those individuals had died from natural causes based on a follow-up survey done in 2004.
The body composition of the study subjects was measured using bioelectrical impedance, which involves running an electrical current through the body
Muscle allows the current to pass more easily than fat does, due to muscle's water content. In this way, the researchers could determine a muscle mass index — the amount of muscle relative to height — similar to a body mass index. They looked at how this muscle mass index was related to the risk of death.
They found that all-cause mortality was significantly lower in the fourth quartile of muscle mass index compared with the first quartile. "In other words, the greater your muscle mass, the lower your risk of death," says Dr. Arun Karlamangla, an associate professor in the geriatrics division at the Geffen School and the study's co-author. "Thus, rather than worrying about weight or body mass index, we should be trying to maximize and maintain muscle mass."
This study does have some limitations
For instance, one cannot definitively establish a cause-and-effect relationship between muscle mass and survival using a cohort study such as NHANES III. "But we can say that muscle mass seems to be an important predictor of risk of death," Srikanthan says in the news release. "In addition, bioelectrical impedance is not the most advanced measurement technique, though the NHANES III measurements were conducted in a very rigorous fashion "and practically, this is the best situation possible in a study of this size," she notes.
"Despite these limitations, this study establishes the independent survival prediction ability of muscle mass as measured by bioelectrical impedance in older adults, using data from a large, nationally representative cohort," Srikanthan and Karlamangla write, adding that BMI's association with mortality in older adults has proven inconsistent. "We conclude that measurement of muscle mass relative to body height should be added to the toolbox of clinicians caring for older adults. Future research should determine the type and duration of exercise interventions that improve muscle mass and potentially increase survival in (healthy), older adults." NIH/NIA grant P30 AG028748 funded the research.
You also may wish to check out the abstracts of these recent studies: New Analysis Suggests Whole Diet Approach to Lower Cardiovascular Risk Has More Evidence Than Low-Fat Diets, Mediterranean-Style Diets Most Successful, Reports The American Journal of Medicine, and Study Strengthens Link Between Low Dietary Fiber Intake and Increased Cardiovascular Risk, Results Reported in The American Journal of Medicine.