BACKGROUND
Obesity causes frailty in older adults; however, weight loss might
accelerate age-related loss of muscle and bone mass and resultant sarcopenia
and osteopenia.
METHODS
In this clinical trial involving 160 obese older adults, we evaluated
the effectiveness of several exercise modes in reversing frailty and
preventing reduction in muscle and bone mass induced by weight loss.
Participants were randomly assigned to a weight-management program plus one
of three exercise programs — aerobic training, resistance training,
or combined aerobic and resistance training — or to a control group
(no weight-management or exercise program). The primary outcome was the
change in Physical Performance Test score from baseline to 6 months (scores
range from 0 to 36 points; higher scores indicate better performance).
Secondary outcomes included changes in other frailty measures, body
composition, bone mineral density, and physical functions.
RESULTS
A total of 141 participants completed the study. The Physical
Performance Test score increased more in the combination group than in the
aerobic and resistance groups (27.9 to 33.4 points [21%
increase] vs. 29.3 to 33.2 points [14%
increase] and 28.8 to 32.7 points [14%
increase], respectively; P=0.01 and P=0.02 after
Bonferroni correction); the scores increased more in all exercise groups
than in the control group (P<0.001 for between-group comparisons).
Peak oxygen consumption (milliliters per kilogram of body weight per minute)
increased more in the combination and aerobic groups (17.2 to 20.3
[17% increase] and 17.6 to 20.9 [18%
increase], respectively) than in the resistance group (17.0 to 18.3
[8% increase]) (P<0.001 for both
comparisons). Strength increased more in the combination and resistance
groups (272 to 320 kg [18% increase] and 288 to 337
kg [19% increase], respectively) than in the aerobic
group (265 to 270 kg [4% increase]) (P<0.001
for both comparisons). Body weight decreased by 9% in all exercise
groups but did not change significantly in the control group. Lean mass
decreased less in the combination and resistance groups than in the aerobic
group (56.5 to 54.8 kg [3% decrease] and 58.1 to
57.1 kg [2% decrease], respectively, vs. 55.0 to
52.3 kg [5% decrease]), as did bone mineral density
at the total hip (grams per square centimeter; 1.010 to 0.996
[1% decrease] and 1.047 to 1.041
[0.5% decrease], respectively, vs. 1.018 to 0.991
[3% decrease]) (P<0.05 for all comparisons).
Exercise-related adverse events included musculoskeletal injuries.
CONCLUSIONS
Of the methods tested, weight loss plus combined aerobic and
resistance exercise was the most effective in improving functional status of
obese older adults. (Funded by the National Institutes of Health; LITOE
ClinicalTrials.gov number, NCT01065636.)
Background
Obesity exacerbates the age-related decline in insulin sensitivity and is associated with risk for cardiometabolic syndrome in older adults; however, the appropriate treatment for obese older adults is controversial.
Objective
To determine the independent and combined effects of weight loss and exercise on cardiometabolic risk factors in obese older adults.
Design
One-hundred-seven obese (BMI≥30 kg/m2) older (≥65 yrs) adults with physical frailty were randomized to control group, diet group, exercise group, and diet-exercise group for 1 year. Outcomes for this study included change in insulin sensitivity index (ISI), glucose tolerance, central obesity, adipocytokines, and cardiometabolic syndrome.
Results
Although similar increases in ISI occurred in the diet-exercise and diet groups at 6 months, the ISI improved more in the diet-exercise than in the diet group at 12 months (2.4 vs. 1.2; between-group difference, 1.2; 95% CI, 0.2-2.1); no changes in ISI occurred in both exercise and control groups. The diet-exercise and diet groups had similar improvements in insulin area under the curve (AUC) (−2.9 and −2.9 ×103mg.min/dl), glucose AUC (−1.4 and −2.2×103mg.min/dl), visceral fat (−787 and −561 cm3), tumor-necrosis factor (−17.0 and −12.8 pg/mL), adiponectin (5.0 and 4.0 ng/mL), waist circumference (−8.2 and −8.4 cm), triglyceride (−30.7 and −24.3 g/dL), and systolic/diastolic BP (−15.9 and −13.1/−4.9 and −6.7 mmHg), while no changes in these parameters occurred in both exercise and control groups. The cardiometabolic syndrome prevalence decreased by 40% in the diet-exercise and by 15% in the diet group. Body weight decreased similarly in the diet-exercise and diet groups (−8.6 and −9.7kg) but not in the exercise and control groups.
Conclusions
In frail, obese older adults, lifestyle interventions associated with weight loss improve insulin sensitivity and other cardiometabolic risk factors, but continued improvement in insulin sensitivity is only achieved when exercise training is added to weight loss.
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