Association Of Leptin And RMR In Obese Elderly Adults With Different Levels Of Physical Activity

Abstract

PURPOSE: The aims of this study were1) to examine potential sex-related differences in leptin, resting metabolic rate (RMR) and metabolic markers2) to assess differences in leptin, RMR and metabolic markers between low MVPA group and high MVPA group3) to assess whether being physically active may play a role in the associations between leptin, RMR and physical activity. METHODS: The subjects were 73 women (age=64.1±6.1years,percent body fat=39.1±4.8%) and 37 men (age=66.3±5.6years,percent body fat=29.7±4.7%). RMR was measured by indirect calorimetry (Metamax 3B-R2 Metabolic Measurement system, German) and body composition by the DXA (GE Lunar Prodigy, USA). Serum leptin and lipid and glucose metabolism makers’ levels were determined by radioimmunoassay. Waist-mounted triaxial accelerometer Actigraph GT3X-BT was used to make objective 7-day recordings of physical activity. Based on the mean of the minutes spent in MVPA (180 min/week), subjects were divided into low MVPA group (n=50, percent body fat=37.1±7.0%) and high MVPA group (n=56, percent body fat=34.5±6.1%). RESULTS: Leptin and HDL cholesterol levels were higher in women than men (both p<0.01), while men presented higher fat free mass and RMR (both p<0.01) than women. Leptin, insulin, HOMA-IR, percent body fat were higher in low MVPA than high MVPA group (all p<0.05), RMR and metabolic markers, however, were not found significant differences (all p>0.05). Leptin levels was associated with RMR negatively and PBF positively (r=-0.36, p=0.013;r=0.645,p=0.0001)in low MVPA group, leptin levels was associated with RMR negatively and PBF positively (r=-0.511, p=0.0001;r=0.631,p=0.0001)in high MVPA group. The negative association of RMR with proportion of sedentary (r=-0.304, p=0.027) and the negative association of leptin with proportion of MVPA (r=-0.303, p=0.023)were only found in high MVPA group. CONCLUSIONS: Leptin may play a role in energy metabolism in overweight and obese elderly adults. Obesity is associated with energy metabolism and metabolic markers both in women and men. The relationship of leptin with energy metabolism and insulin resistance might be moderated by levels of physical activity. Acknowledgements: This work was supported by Ministry of Science and Technology of the People's Republic of China (Grants No.2013FY114700).