Joint associations of physical activity and sedentary behaviors with body mass index: results from a time use survey of US adults.

OBJECTIVE: Obesity risk is negatively associated with physical activity and positively associated with time spent in sedentary behaviors. Yet, it is not known how different combinations of sedentary and active behavior are associated with body mass index (BMI). This study examined the interaction between time spent in physical activity and sedentary behavior on BMI in US adults. DESIGN: Cross-sectional, data from the 2006 American Time Use Survey. SUBJECTS: 10 984 non-underweight adults (aged 21 + years). MEASUREMENT: A phone interview assessed all activities performed in the past 24 h, height, weight, health status, and other sociodemographic characteristics. Time spent in (1) moderate-to-vigorous leisure-time physical activity (MVPA), (2) active transportation (walking, biking), (3) sedentary leisure activities (TV/movie watching, computer use, playing games, reading), and (4) sedentary transportation (motorized vehicles) was determined from activity coding. BMI was calculated. RESULTS: After adjusting for age, gender, education level, race/ethnicity, and health status, sample-weighted linear regressions found significant interactions for leisure MVPA x TV/movies, leisure MVPA x playing games, active transportation x sedentary transportation, and active transportation x reading (Ps<0.0001). For example, the group of adults watching <60 min per day of TV/movies and engaging in > or =60 min per day of leisure MVPA had lower average BMI compared to the group watching <60 min per day of TV/movies and reporting <60 min per day of leisure MVPA (P<0.0001). In contrast, for adults watching > or =189 min per day of TV/movies, there was not a significant difference in BMI by time spent in leisure MVPA. CONCLUSION: Data from a US time use survey indicate that the strength of the association between certain types of sedentary behavior and BMI varies according to time spent in certain types of physical activity and vice versa.

Gender differences in cardiovascular response to dementia caregiving.

PURPOSE: This study examined gender differences in cardiovascular responses to laboratory-based stress, as well as in ambulatory hemodynamic (i.e., blood pressure and heart rate) functioning among caregivers of persons with dementia. DESIGN & METHODS: Participants were 25 men and 25 women caregivers, matched on age, type of care recipient's dementia, and relationship to the care recipient. After cardiovascular reactivity to a laboratory-based caregiving stressor was assessed, the ambulatory hemodynamic functioning levels of caregivers were measured in caregivers' natural environments. RESULTS: Female caregivers displayed greater systolic and diastolic blood pressure reactivity to a laboratory-based stress task (i.e., discussing caregiving difficulties) compared with male caregivers (p < or =.01). In contrast, no gender differences were found for ambulatory hemodynamic functioning when aggregated overall or when in the presence of the care recipient. IMPLICATIONS: Laboratory-based findings suggest that female caregivers experience greater blood pressure reactivity to caregiving-related stress than do male caregivers. However, these laboratory-based gender differences may not generalize to differences in hemodynamic functioning in caregivers' daily lives.

The mediating effects of situational control on social support and mood following a stressor: a prospective study of dementia caregivers in their natural environments.

OBJECTIVES: The present study examined, prospectively and within the context of stress experienced in the natural environment, whether situational control served as a mediator between perceived social support and caregiver's mood. METHODS: Data came from baseline assessments of individuals participating in health promotion interventions for women caregivers. Participants were 49 female caregivers of dementia patients who monitored their own acute psychological states during the day. RESULTS: Results revealed that although the occurrence of a situational stressor increased negative mood, greater perceived support reduced the detrimental impact of a stressor on negative mood. Moreover, path analyses revealed that changes in situational control partially mediated the relationship between perceived support and stress-induced negative mood changes. However, changes in control did not serve as a mediator in analyses focused on happiness. DISCUSSION: Results suggest that caregivers with greater perceived support were less emotionally reactive to stress occurring in their natural environments because of, in part, sustained or increased situational control.

The interplay of work and caregiving: relationships between role satisfaction, role involvement, and caregivers' well-being.

This study applied theory from the general work and family literature to the dual roles of work and caregiving, in order to examine whether level of satisfaction and time involvement in each of these roles moderate the effects of stress in the other role on well-being. Respondents were 118 employed women who were providing care to an impaired parent or parent-in-law. As predicted, greater time involvement in work was found to buffer women from the negative effects of caregiving stress. Satisfaction with caregiving and satisfaction with work were directly associated with better well-being, beyond the effects of stress in both roles. However, women who experienced high levels of caregiving stress and who were highly satisfied with work were especially vulnerable to depression. These findings illustrate the importance of examining the effects of caregiving stress on well-being in the context of work-related experiences.

Where two roles intersect: spillover between parent care and employment.

Spillover between the roles of parent care and employment was assessed in a sample of 105 employed adult daughter caregivers. This research examined how these 2 roles affect one another, both positively and negatively, and how such spillover was related to caregivers' psychological well-being. Path analyses indicated that negative spillover was an important mediating mechanism in the relationship between role stress and depression. In contrast, no evidence was found to suggest that positive spillover mediated the relationship between role satisfaction and positive affect. Findings extend prior research that has documented that caregiving and employment can interfere with one another by demonstrating that such spillover has implications for caregivers' emotional health.