A structured exercise program may improve mobility even among the most obese elderly patients, new data indicate.
Results from a post hoc analysis of a large, prospective, randomized trial examining the impact of physical activity on mobility disability in adults aged 70 to 89 years were published June 26 in Obesity by Stephen B Kritchevsky, PhD, director of the Sticht Center on Aging and professor, Gerontology and Geriatric Medicine Center on Diabetes, Obesity, and Metabolism at Wake Forest University, Winston-Salem, North Carolina, and colleagues.
In the Lifestyle Interventions and Independence for Elders (LIFE) Study, a structured program focused on walking, strength, balance, and flexibility training produced a significant 18% reduction in major mobility disability compared with those randomized to simply a health-education program (JAMA. 2014;311:2387-2396).
Now, in a new analysis in which the subjects from that study were divided into four groups based on baseline body-mass index (BMI) and waist circumference, the findings were contrary to what the authors had hypothesized: rather than benefiting less, those in the highest obesity category (class 2+) actually benefited the most.
That group was the only one to achieve statistical significance, although there was a trend toward benefit for the physical-activity program across the board regardless of body size.
“We wanted to look at different obesity classes because prior data suggest that obesity may blunt the benefits of physical activity for the prevention of mobility disability.…We were surprised to see the strongest apparent benefit of the intervention was in the heaviest group,” Dr Kritchevsky told Medscape Medical News.
The clinical message, he said, is: “You should not give up on an older person just because it looks like the odds are stacked against them….We know from our research that it’s never too late to start.”
Dr Kritchevsky noted that local community senior centers often offer structured exercise programs similar to the one used in the LIFE study and that the National Institute on Aging also has a web page with instructional videos of safe exercises that seniors can perform at home. While some seniors may need to work on strengthening before they can achieve daily walking goals, overall “it doesn’t take a lot to get this benefit,” he noted.
Overall Trend for Greater Mobility, With Significance for Heaviest Group
The current analysis included 1613 inactive adults aged 70 to 89 at high risk for mobility disability based on scoring 9 or less on the 12-point Short Physical Performance Battery (SPPB), comprising tests of walking, rising from a chair without using arms, and standing balance.
Subjects were randomized to a physical-activity program or to a health-education (control) arm.
The physical-activity program focused on walking, strength, balance, and flexibility training, with goals of 30 minutes of walking at moderate intensity, 10 minutes of lower-extremity strength training using ankle weights, and 10 minutes of balance training of major muscle groups. Participants attended twice-weekly in-person sessions and were asked to perform activities at home for three to four times weekly and to keep an activity log.
The health-education arm involved once-weekly 60- to 90-minute in-person discussions on topics such as nutrition, safety, and legal/financial issues related to aging.
The participants were classified into four categories based on BMI and waist circumference:
- Nonobese without abdominal obesity (BMI <30 kg/m2; n=437).
- Nonobese with abdominal obesity (waist circumference >102 cm [men], >88 cm [women]; n=434).
- Class 1 obesity (BMI 30 to <35 kg/m2; n=430).
- Class 2 to 3 obesity (BMI >35 kg/m2; n=312).
The median follow-up time was 2.7 years. At 24 months, attendance at the scheduled center-based intervention sessions was 63% for the physical-activity program and 73% for the health-education program.
The primary outcome of major mobility disability was defined as the inability to complete a 400-m-walk test within 15 minutes without sitting and without the help of another person or walker. Point estimates for the intervention effect were <1 in each obesity category and the strongest effect was observed in those with class 2+ obesity (hazard ratio, 0.69). Interactions between obesity category and treatment arm did not reach statistical significance (P = .49).
There was no overall effect of the intervention on 400-m-walk speed over the first 24 months of the study (P = .73), nor was there evidence of an interaction between intervention arm and obesity status (P = .36).
However, there was an overall beneficial effect of the physical-activity program on SPPB score (mean change, 0.23; P = .013), with the largest effect on the group with BMI <30 and abdominal obesity. But there was no statistical interaction between intervention arm and obesity category (P = .23).
In the class 2+ obesity group, participants in the health-education arm reported no increase in their walking at 6 months — remaining around 30 minutes/week — while the physical-activity group increased their walking to 135 minutes/week.
Although this level was still below that of the lesser obese categories, it could at least partly explain the mobility benefit seen in the heaviest group, the authors note.
Dr Kritchevsky commented that physicians should advocate for community resources such as senior centers with health-promotion programs if they’re not already available, given that seniors may not feel comfortable at facilities such as YMCAs and gyms that tend to target younger people: “If you don’t have them, let somebody know you need them.”
The LIFE Study is funded by a National Institutes of Health (NIH)/National Institute on Aging Cooperative Agreement and a supplement from the National Heart, Lung, and Blood Institute and sponsored in part by the Intramural Research Program, National Institute on Aging, NIH. The research is partially supported by the Claude D Pepper Older Americans Independence Centers at the University of Florida, Wake Forest University, Tufts University, University of Pittsburgh, and Yale University and the NIH/ National Center for Research Resources Clinical and Translational Science Awards at Stanford University. Investigators have also received support from the Boston Rehabilitation Outcomes Center and the US Department of Agriculture. Dr Kritchevsky has no relevant financial relationships. Disclosures for the coauthors are listed in the paper.
Obesity. Published online June 26, 2017. Abstract