Light physical activity is a better determinant of lower adiposity during the menopausal transition.

OBJECTIVE: To investigate the relationship between time spent performing physical activity (PA) and adiposity across the menopausal transition. METHODS: Body weight and body composition were analyzed in 65 women (47-54 years old; body mass index 23.2 ± 2.4 kg/m(2)) in a 5-year prospective study. Time spent in PA of varying intensities (sedentary, light, moderate and vigorous) was determined from 7-day accelerometer measurement and energy intake with a 7-day food diary. RESULTS: Significant negative correlations were observed between the time spent in light-intensity PA and fat mass (FM) (r = -0.38, p < 0.005), central FM (r = -0.36, p < 0.005), peripheral FM (r = -0.33, p < 0.01), and percent body fat (r = -0.42, p < 0.001) at year 1, respectively. No significant correlations were noted between measures of adiposity and time spent performing either moderate or vigorous PA. Analyses using tertiles of time spent in light PA at year 1 showed that FM (20.7 ± 4.0 vs. 20.3 ± 6.6 vs. 16.6 ± 4.6 kg, p < 0.05), central FM (10.1 ± 2.6 vs. 10.0 ± 3.8 vs. 7.8 ± 2.4 kg; p < 0.05) and percent body fat (34.5 ± 5.1 vs. 32.2 ± 7.7 vs. 28.1 ± 6.2%, p < 0.01) were all significantly lower in women in the highest tertile. These differences remained significant after covariate analyses using time spent in moderate- and high-intensity PA and total energy intake. Finally, lower levels of FM, percent body fat, central and peripheral FM persisted in women who spent more time in light PA (highest tertiles) over the 5-year follow-up. CONCLUSION: Our results suggest that the time spent performing light PA may have a greater impact on adiposity than moderate and/or vigorous PA, an observation independent of the menopausal status.

Relationship of mid-thigh adiposity to the metabolic syndrome in postmenopausal women.

BACKGROUND: In postmenopausal women, a population at risk for the metabolic syndrome, the relative contribution of central fat versus peripheral muscle fat to the metabolic risk profile is unknown. This study explored the relationship between muscle fat infiltration derived from computed tomography (CT) scans and metabolic syndrome. METHODS: Mid-thigh CT scans measured the surface of muscle with low attenuation (LAMS) [0-34 Hounsfield units (HU)], which represented the specific component of fat-rich muscle. Insulin sensitivity was evaluated by an euglycemic-hyperinsulinemic clamp. National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria were used to determine the presence of the metabolic syndrome. RESULTS: A total of 103 postmenopausal women were studied. Metabolic syndrome was found in 43 women with significantly higher levels of abdominal adiposity, higher LAMS (27 +/- 8 vs. 23 +/- 7 cm(2)), and lower insulin sensitivity compared to those without the metabolic syndrome. Women with higher levels of LAMS presented higher metabolic risk features such as higher blood pressure, abdominal adiposity, inflammatory markers, and blood lipid levels. LAMS and visceral adipose tissue correlated significantly with the presence of metabolic syndrome, but these relationships were lost when LAMS was adjusted for visceral adipose tissue but not when visceral adipose tissue was adjusted for LAMS. CONCLUSIONS: These results suggest that postmenopausal women who present with metabolic syndrome had increased fat-rich mid-thigh muscle. Moreover, women with more fat-rich muscle had many features of the metabolic syndrome. These relations were weakened when visceral adipose tissue was taken into account suggesting that LAMS may play a relatively smaller role, compared to VAT, in the contribution to the metabolic syndrome.

Validation of a simple index (SIisOGTT) of insulin sensitivity in a population of sedentary men.

AIM: The ongoing obesity epidemic is associated with numerous health problems related to altered metabolic function. Among these is type 2 diabetes, characterized by lowered insulin sensitivity (IS). Consequently, the development of simple indices to assess IS has research and clinical importance. The SI(is)OGTT, a new index of IS, was recently described by Bastard et al. (Diabetes & Metabolism 2007;33:261-8), and validated in sedentary, non-diabetic, overweight and obese postmenopausal women. The aim of the present study was to validate the index in men. METHODS: The data used in this project came from sedentary men (n=36), aged 34-53 years, all of whom underwent a hyperinsulinaemic-euglycaemic clamp and 2-hour oral glucose tolerance test (OGTT). Correlations with M/I (glucose infusion rate [GIR] divided by insulin concentration), GIR and GIR divided by fat-free mass (FFM) were obtained by four well-known indices (HOMA, QUICKI, Cederholm and Matsuda) as well as with the new SI(is)OGTT index. Pearson correlations and Bland-Altman analyses were obtained for every index versus clamp value. RESULTS: The best correlate of IS in the present study was the SI(is)OGTT (r=0.84, P<0.0001). The agreement of this method with the hyperinsulinaemic-euglycaemic clamp, as assessed by Bland-Altman plots, was similar to those of the other indices and to those previously described in postmenopausal women. CONCLUSION: The new index proposed by Bastard et al. is as good a predictor of IS in sedentary men as the other commonly used indices, and appears to be as reliable in this population as it was in the original study of postmenopausal women.