Prospective study on sedentary behaviour patterns and changes in body composition parameters in older women: A compositional and isotemporal substitution analysis.

BACKGROUND & AIMS: The aims of this study were to examine the prospective compositional associations between sedentary behaviour (SB) patterns and longitudinal changes in body composition parameters, and to use compositional isotemporal substitution modelling to analyse the longitudinal changes in body composition parameters associated with time reallocation from SB to physical activity (PA) in older women. METHODS: The study included women aged 60 years and older (n = 182) with valid data at baseline and at the subsequent 7-year follow-up. For both time points, the ActiGraph GT1M accelerometer was used for SB and PA assessments and multi-frequency bioimpedance analysis was used to assess the body composition parameters related to adiposity and muscle mass. Compositional regression models were used to analyse the associations between proportion of time spent in sedentary bouts of different duration and longitudinal changes in body composition parameters. A compositional isotemporal substitution model was created to estimate the differences in body composition parameters associated with one-to-one time reallocations between baseline SB and PA. RESULTS: A significant increase in fat mass index (ßilr1 = 0.61, 95% confidence interval [CI]: 0.18, 1.04) and visceral adipose tissue (ßilr1 = 6.01, 95% CI: 1.52, 10.5) was associated with a higher baseline proportion of time spent in long sedentary bouts (i.e. sedentary bout of ≥30 min). Reallocating 1 h/week and 3.5 h/week from the time spent in long sedentary bouts in favour of light PA was associated with a significant decrease in fat mass index by 0.78% (95% CI: 0.24, 1.32) and 3.13% (95% CI: 0.97, 5.29), respectively. No association was found for indicators of muscle mass. CONCLUSIONS: This study suggests that long-term adiposity status could be improved by increasing the proportion of time spent in light PA at the expense of time spent in prolonged SB. This finding may help in designing more effective and feasible interventions for the maintenance of healthy body composition in advanced age.

Adiposity and changes in movement-related behaviors in older adult women in the context of the built environment: a protocol for a prospective cohort study.

BACKGROUND: In older adults, sedentary behaviors increase while physical activity decreases over time following the compositional nature of 24-h behaviors. These changes in movement-related behaviors (MRBs) might be associated with unhealthy weight gain and several health comorbidities. However, information is lacking on how obesity influences longitudinal changes in the composition of MRBs in older adults. Furthermore, the moderating effect of the built environment on prospective associations between obesity and MRBs in older adults is not fully understood. Therefore, using an integrated time-use approach, this study aims to identify prospective associations between obesity and MRBs together with an assessment of the moderating effect of the built environment in elderly women. METHODS: The study was designed as a prospective 7-year follow-up study. It is based on two previous cross-sectional studies that enable the use of participant data (women aged 60+ years, n = 409) as a baseline dataset in the current study. All methods designed for 7-year follow-up are based on previous studies. The data collection comprises device-based measurement of MRBs (ActiGraph GT1M accelerometer), objective assessment of body adiposity (multi-frequency bioelectrical impedance analysis), subjective assessment of the built environment (NEWS-A questionnaire), and other possible confounding factors. Time spent in sedentary behavior, light physical activity, and moderate-to-vigorous physical activity will be used as three components in a composition reflecting individual MRBs. In linear multiple compositional regression analysis assessing the prospective association between obesity and MRBs, the 7-year follow-up composition of the three mentioned components represents the dependent variable. The 7-year changes in the percentage of body fat (body adiposity), baseline composition of MRBs, and parameters of the built environment represent regressors. DISCUSSION: This study will use an integrated time-use approach to explore causality from obesity to device-measured behaviors in older women. The design and respective analysis consider the compositional nature of MRBs data and the potential moderating effects of various factors. A comprehensive assessment of causality may help to develop multilevel interventional models that enhance physical activity in older adults.

Sedentary behaviour and adiposity in community-dwelling women aged 55 and older.

This study aimed to describe sedentary behaviour in detail and assess its association with adiposity in older adult women. Data from 314 community-dwelling women (mean age 66.6 ± 6.5 years) from Czech Republic, Poland, and Slovakia were analyzed. Fat mass percentage was used as an indicator of adiposity, measured by bioelectrical impedance analysis. The patterns of sedentary behaviour were monitored using an accelerometer, and 1-9, 10-29 and 30 min. bouts were analyzed. We performed a multiple linear regression analysis to assess the association between variables. There was a significant association of fat mass percentage with time spent in bouts with a duration 10-29 min. (β = 0,03, p < 0,01) and the frequency of all analyzed bouts (β ranging -0,08-0,6; p < 0,05) which was independent of age, physical activity, demographic, socio-economic and health factors. Our results suggest that the sedentary behaviour patterns are significantly associated with adiposity. Reducing of sedentary time should be considered when planning a prevention programs or interventions.

Interaction of cryptogein with its binding sites in tobacco plasma membrane studied using the piezoelectric biosensor.

Elicitins are low-molecular-weight proteins representing the elicitor family secreted by many species of the oomycete Phytophthora. Elicitins induce a hypersensitive reaction in tobacco, a process that is triggered by binding of elicitin to the high-affinity site on the plasma membrane. Specific interaction of cryptogein with the binding sites on tobacco plasma membranes was studied using the piezoelectric biosensor in real time in a flow-through mode. Cryptogeins (wild-type and mutant forms) were covalently immobilized on the sensing surface, and membrane vesicles containing receptors were in solution. Kinetic characterization of the interaction provided values of kinetic rate association (k(a))=5.74 . 10(6)M(1)s(-1) and kinetic rate dissociation (k(d))=6.8710(-4)s(-1) constants, respectively. The kinetic equilibrium dissociation constant was calculated as K(D)=12.0 nM. The piezoelectric biosensor appeared to be a convenient tool for studying interactions of receptors embedded in membrane vesicles.