All four studies, and an accompanying editorial commentary appear in the 25 January issue of the Archives of Internal Medicine.
In the accompanying editorial, Drs Jeff Williamson and Marco Pahor, of the University of Florida, point out that previous studies have linked exercise to beneficial effects on a range of conditions and diseases, including obesity, diabetes, heart disease, cancer, lung disease, arthritis, falls and fractures, that can hamper older people's ability to get on with their day to day tasks and lead indendepent lives.
"Regular physical activity has also been associated with greater longevity as well as reduced risk of physical disability and dependence, the most important health outcome, even more than death, for most older people."
And now, they suggest, these four new studies advance the field and help us better understand the "full range of important aging-related outcomes for which exercise has a clinically relevant impact".
Exercise in Middle Age Linked to Better Health in Later Life
In the first of the four studies, Dr Qi Sun, of the Harvard School of Public Health, Brigham and Women's Hospital and Harvard Medical School, Boston, and colleagues looked at health data from 13,535 participants taking part in the Nurses' Health Study.
They found that among women aged 70 and over, those who engaged in regular physical activity in their middle age were more likely to show signs of better overall health.
The women completed questionnaires about their physical activity in 1986, when their average age was 60.
When the researchers looked at data on health outcomes in those women that survived to age 70 and over from 1995 to 2001, they found that those who had reported higher levels physical activity in their middle age were less likely to have undergone heart surgery, have chronic diseases, or any physical, cognitive or mental impairments.
The researchers wrote that they also found:
"Increasing energy expenditure from walking was associated with a similar elevation in odds of successful survival."
They concluded that as the US population is a rapidly aging one and nearly 25 per cent of Americans do not pursue leisure time activities:
"Our findings appear to support federal guidelines regarding physical activity to promote health among older people and further emphasize the potential of activity to enhance overall health and well-being with aging."
They said people might be more motivated to pursue physical activities if they thought it would increase their chance of being fit and well in old age rather than just extending their lifespan.
Resistance Training Linked to Improved Cognitive Skills in Older Women
In the second of the four studies, Dr Teresa Liu-Ambrose, of Vancouver Coastal Health Research Institute and University of British Columbia, Vancouver, Canada, and colleagues, enrolled 155 women aged 65 to 75 and randomly assigned them to one of three groups that undertook to follow a particular exercise pattern for a year.
One group of 54 participants did resistance training once a week, another group of 52 did it twice a week, and a third group of 49, the control group, didn't do resistance training: they took part in twice-weekly sessions of balance and tone training.
The results showed that after following their exercise program for a year, compared to those in the balance and tone group, the women in both resistance training groups improved their performance on the Stroop test, a cognitive test of selective attention and conflict resolution.
Liu-Ambrose and colleagues also wrote that:
"Task performance improved by 12.6 per cent and 10.9 per cent in the once-weekly and twice-weekly resistance training groups, respectively; it deteriorated by 0.5 per cent in the balance and tone group."
The women in the resistance training groups also improved muscular function.
The authors concluded that:
"This has important clinical implications because cognitive impairment is a major health problem that currently lacks a clearly effective pharmaceutical therapy and because resistance training is not widely adopted by seniors."
"The doses of resistance training we used in this study fall within those recommended by the 2008 Physical Activity Guidelines for seniors," they added.
Exercise May Be Linked to Reduced Cognitive Impairment in Older Adults
In the third of the four studies linking exercise to healthier aging, Dr Thorleif Etgen of the Technische Universität München, Munich, and Klinikum Traunstein, Germany, and colleagues who followed a group of older adults for two years, found that moderate or high physical activity appeared to be linked with a lower risk of developing cognitive impairment.
The participants, who were older than 55 years, enrolled in a community-based prospective cohort study in southern Bavaria, Germany between 2001 and 2003 and were followed for 2 years. They gave data about their physical activity level and underwent tests of cognitive function (the 6-item Cognitive Impairment Test). The main outcome measure was the level of cognitive impairment after the 2 years of follow up.
The results showed that at the start of the study, 418 (10.7 per cent) of the participants had cognitive impairment, leaving 3,485 unimpaired.
After 2 years, 207 (5.9 per cent) of the unimpaired participants developed cognitive impairment.
When they analysed the data on these additional 207, the researchers found that compared with those who did no physical activity, those who reported moderate (exercising less than 3 times a week) or high (3 times a week or more) levels of physical activity at the start of the study (baseline) "showed a significantly reduced risk of incident cognitive impairment after 2 years".
"The incidence of new cognitive impairment among participants with no, moderate and high activity at baseline was 13.9 per cent, 6.7 per cent and 5.1 per cent, respectively," they wrote.
The researchers concluded that further studies should be done to assess how much and what types of exercise might prevent or delay cognitive impairment and to what extent.
Exercise Linked to Denser Bones and Lower Risk of Falls in Older Women
For the fourth study, which ran from May 2005 to July 2008, Dr Wolfgang Kemmler and colleagues at Freidrich-Alexander University of Erlangen- Nuremberg, Erlangen, Germany, recruited and randomly assigned 246 women aged 65 and over either to to follow an exercise program (the exercise group) or a wellness program (the control group) for 18 months.
They found that compared to the control group, the women in the exercise group appeared to have denser bones and a reduced risk of falls, but not a reduced risk of cardiovascular disease.
The exercise group followed a multipurpose 4 days per week exercise program that emphasized exercise intensity, while the controls followed a general wellness program that focused on wellbeing with a low intensity and low frequency program.
The main outcome measures were bone mineral density (BMD), number of falls, risk of coronary heart disease (the Framingham CHD Risk Calculator, which takes into account cholesterol level, blood pressure and presence of diabetes), and health care costs.
The results showed that among the 227 women who completed the study, the 115 in the exercise group had higher bone mineral density in the spine and hip and a 66 per cent reduced rate of falls.
Also, women in the control group were twice as likely to have fractures due to falls compared to those in the exercise group (12 versus 6), but the 10-year risk of cardiovascular disease went down in both groups with no difference between them.
There were no significant differences in direct health care costs per participant between the two groups.
The researchers concluded that:
"Compared with a general wellness program, our 18-month exercise program significantly improved BMD and fall risk, but not predicted CHD risk, in elderly women. This benefit occurred at no increase in direct costs."
"Because this training regimen can be easily adopted by other institutions and health care providers, a broad implementation of this program is feasible," they wrote.
"Physical Activity at Midlife in Relation to Successful Survival in Women at Age 70 Years or Older."
Qi Sun; Mary K. Townsend; Olivia I. Okereke; Oscar H. Franco; Frank B. Hu; Francine Grodstein.
Arch Intern Med. 2010;170:194 -201, published online 25 January 2010.
"Resistance Training and Executive Functions: a 12-Month Randomized Controlled Trial."
Teresa Liu-Ambrose; Lindsay S. Nagamatsu; Peter Graf; B. Lynn Beattie; Maureen C. Ashe; Todd C. Handy.
Arch Intern Med. 2010;170:170 -178, published online 25 January 2010.
"Physical Activity and Incident Cognitive Impairment in Elderly Persons: the INVADE Study."
Thorleif Etgen; Dirk Sander; Ulrich Huntgeburth; Holger Poppert; Hans Forstl; Horst Bickel.
Arch Intern Med. 2010;170:186 -193, published online 25 January 2010.
"Exercise Effects on Bone Mineral Density, Falls, Coronary Risk Factors, and Health Care Costs in Older Women: the Randomized Controlled Senior Fitness and Prevention (SEFIP) Study."
Wolfgang Kemmler; Simon von Stengel; Klaus Engelke; Lothar Haberle; Willi A. Kalender.
Arch Intern Med. 2010;170:179 -185, published online 25 January 2010.