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Weight Loss and Exercise Differentially Affect Insulin Sensitivity, Body Composition, Cardiorespiratory Fitness, and Muscle Strength in Older Adults With Obesity: A Randomized Controlled Trial.
Brennan, AM, Standley, RA, Anthony, SJ, Grench, KE, Helbling, NL, DeLany, JP, Cornnell, HH, Yi, F, Stefanovic-Racic, M, Toledo, FGS, et al
The journals of gerontology. Series A, Biological sciences and medical sciences. 2022;77(5):1088-1097
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Plain language summary
Aging is marked by increased risk for type 2 diabetes, reduced muscle mass and strength (ie, sarcopenia), decreased physical function and cardiorespiratory fitness, ectopic fat deposition, and insulin resistance all of which increase the risk for physical disability, morbidity, and mortality. These adverse health consequences associated with advanced age are exacerbated with obesity and physical inactivity. The aim of this study was to investigate the effects of weight loss with or without exercise on skeletal muscle insulin sensitivity, exclusively in obese older adults. This study is a 2-site, 6-month randomized controlled trial with a parallel group design. Eighty-six older (60–80 years of age), physically inactive men and women with obesity were randomised into one of the 3 treatments (1:1:1 allocation ratio): control (health education), calorie restriction-induced weight loss, and weight loss with exercise. Results suggest that weight loss via calorie restriction alone is insufficient to significantly improve skeletal muscle insulin sensitivity and requires the addition of exercise to incur benefit, which was also true for clinical measures of insulin resistance including haemoglobin A1C [a blood test that measures the average blood sugar levels over a period of 3 months] and fasting insulin. Authors conclude that regular exercise should be considered as a useful and manageable adjunct to traditional weight loss therapies for older adults with obesity to mitigate risk for chronic disease and maintain functional independence and quality of life.
Abstract
BACKGROUND Aging-related disease risk is exacerbated by obesity and physical inactivity. It is unclear how weight loss and increased activity improve risk in older adults. We aimed to determine the effects of diet-induced weight loss with and without exercise on insulin sensitivity, VO2peak, body composition, and physical function in older obese adults. METHODS Physically inactive older (68.6 ± 4.5 years) obese (body mass index 37.4 ± 4.9 kg/m2) adults were randomized to health education control (HEC; n = 25); diet-induced weight loss (WL; n = 31); or weight loss and exercise (WLEX; n = 28) for 6 months. Insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp, body composition by dual-energy X-ray absorptiometry and MRI, strength by isokinetic dynamometry, and VO2peak by graded exercise test. RESULTS WLEX improved (p < .05) peripheral insulin sensitivity (+75 ± 103%) versus HEC (+12 ± 67%); WL (+36 ± 47%) versus HEC did not reach statistical significance. WLEX increased VO2peak (+7 ± 12%) versus WL (-2 ± 24%) and prevented reductions in strength and lean mass induced by WL (p < .05). WLEX decreased abdominal adipose tissue (-16 ± 9%) versus HEC (-3 ± 8%) and intermuscular adipose tissue (-15 ± 13%) versus both HEC (+9 ± 15%) and WL (+2 ± 11%; p < .01). CONCLUSIONS Exercise with weight loss improved insulin sensitivity and VO2peak, decreased ectopic fat, and preserved lean mass and strength. Weight loss alone decreased lean mass and strength. Older adults intending to lose weight should perform regular exercise to promote cardiometabolic and functional benefits, which may not occur with calorie restriction-induced weight loss alone.
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Inflammation and glucose homeostasis are associated with specific structural features among adults without knee osteoarthritis: a cross-sectional study from the osteoarthritis initiative.
Stout, AC, Barbe, MF, Eaton, CB, Amin, M, Al-Eid, F, Price, LL, Lu, B, Lo, GH, Zhang, M, Pang, J, et al
BMC musculoskeletal disorders. 2018;19(1):1
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Individuals with osteoarthritis (OA) typically present with greater systemic inflammation and impaired glucose homeostasis. Currently it is unclear whether these factors are associated with early-stage OA, namely bone marrow lesions and swelling. The purpose of this cross-sectional study was to investigate the role of inflammation and glucose homeostasis in early-stage OA. Using baseline data from the Osteoarthritis Initiative, 343 participants were enrolled and tested for markers of inflammation and impaired glucose homeostasis. Bone marrow lesions and swelling were also assessed through imaging results. Results indicate that among individuals without OA, those with greater systemic inflammation were more likely to have bone marrow lesions and knee swelling. According to these results, the authors conclude that systemic inflammation and glucose homeostasis are related to structural features of osteoarthritis. Future studies should explore whether these factors are predictive of OA in order to identify therapeutic targets to prevent or delay the onset of knee OA.
Abstract
BACKGROUND Greater age and body mass index are strong risk factors for osteoarthritis (OA). Older and overweight individuals may be more susceptible to OA because these factors alter tissue turnover in menisci, articular cartilage, and bone via altered glucose homeostasis and inflammation. Understanding the role of inflammation and glucose homeostasis on structural features of early-stage OA may help identify therapeutic targets to delay or prevent the onset of OA among subsets of adults with these features. We examined if serum concentrations of glucose homeostasis (glucose, glycated serum protein [GSP]) or inflammation (C-reactive protein [CRP]) were associated with prevalent knee bone marrow lesions (BMLs) or effusion among adults without knee OA. METHODS We conducted a cross-sectional study using baseline data from the Osteoarthritis Initiative. We selected participants who had no radiographic knee OA but were at high risk for knee OA. Blinded staff conducted assays for CRP, GSP, and glucose. Readers segmented BML volume and effusion using semi-automated programs. Our outcomes were prevalent BML (knee with a BML volume > 1 cm3) and effusion (knee with an effusion volume > 7.5 cm3). We used logistic regression models with CRP, GSP, or glucose concentrations as the predictors. We adjusted for age, sex, body mass index (BMI), and Physical Activity Scale for the Elderly (PASE) scores. RESULTS We included 343 participants: mean age = 59 ± 9 years, BMI = 27.9 ± 4.5 kg/m2, PASE score = 171 ± 82, and 64% female. Only CRP was associated with BML prevalence (odds ratio [OR] = 1.43, 95% confidence interval [CI] = 1.09 to 1.87). For effusion, we found an interaction between BMI and CRP: only among adults with a BMI <25 kg/m2 was there a significant trend towards a positive association between CRP and effusion (OR = 1.40, 95% CI = 1.00 to 1.97). We detected a U-shaped relationship between GSP and effusion prevalence. Fasting glucose levels were not significantly associated with the presence of baseline effusion or BML. CONCLUSIONS Among individuals without knee OA, CRP may be related to the presence of BMLs and effusion among normal weight individuals. Abnormal GSP may be associated with effusion. Future studies should explore whether inflammation and glucose homeostasis are predictive of symptomatic knee OA.