Highlights d Diet-induced weight loss leads to muscle mass reduction in obese older adults d Diet-induced muscle loss is attenuated by addition of resistance exercise d Muscle protein synthesis following a meal improves with resistance exercise d Myocellular quality improves with aerobic plus resistance exercise

Background Obesity exacerbates age-related effects on body composition, physical and metabolic function. Which exercise mode is most effective in mitigating these deleterious changes in dieting obese older adults is unknown. Methods In a randomized controlled trial, we performed a head-to-head comparison of aerobic (AEX), resistance (REX), or combination (COMB) exercise during matched weight loss in 160 obese older adults. Prespecified analyses compared 6-month changes in intermuscular adipose tissue (IMAT) and visceral adipose tissue (VAT) assessed using MRI, insulin sensitivity index (ISI) by oral glucose tolerance test, physical function using Modified Physical Performance Test (PPT), VO2peak, gait-speed, and knee strength by dynamometry. Results IMAT and VAT decreased more in COMB than AEX and REX groups (IMAT; -41% vs. -28% and -23% and VAT: -36% vs. -19% and -21%; p=.003 to .01); IMAT and VAT decreased in all groups more than control (CON) (between-group p<.001). ISI increased more in COMB than AEX and REX groups (86% vs. 50% and 39%; p=.005 to .03). PPT improved more in COMB than AEX and REX groups, while VO2peak improved more in COMB and AEX than REX group (all p<.05). Knee strength improved more in COMB and REX than AEX group (all p<.05). Changes in IMAT and VAT correlated with PPT (r=-.28 and -.39), VO2peak (r=-.49 and -.52), gait-speed (r=-.25 and -.36), and ISI (r=-.49 and -.52) (all p<.05). Conclusions Weight loss plus combination aerobic and resistance exercise was most effective in improving ectopic fat deposition and physical and metabolic function in older adults with obesity.

Objective: Because the aromatase enzyme catalyzes the conversion of testosterone to estradiol (E 2 ), the activity of this enzyme could be important in the musculoskeletal health of men with low testosterone. The objective of the present study is to determine the influence of aromatase activity on the bone mineral density (BMD) and body composition of patients with hypogonadism. Design: Cross-sectional study. Methods: The baseline data of 90 patients between 40 and 74 years old who participated in a genetic study of response to testosterone therapy in men with low testosterone (i.e., !300 ng/dl) were analyzed. BMD and body composition were measured by dual-energy X-ray absorptiometry. Serum testosterone was measured by automated immunoassay, E 2 was measured by ultrasensitive enzyme immunoassay, and sex hormone-binding globulin was measured by enzyme immunoassay. Results: Men in the highest tertile of E 2 to testosterone ratio (E 2 :T) had the highest spine BMD (P%0.037), highest truncal fat (PZ0.046), and lowest truncal lean body mass (PZ0.045). A similar pattern was observed in the upper extremities; that is, fat mass significantly increased (PZ0.047), whereas lean mass significantly decreased (PZ0.034) with increasing E 2 :T tertiles. Conclusion: The present findings suggest that in men with hypogonadism, aromatase activity could be an important determinant of musculoskeletal health. Men with high aromatase activity are able to maintain a higher BMD despite low circulating testosterone, but they have lower lean and higher truncal fat mass as compared to those with lower aromatase activity.