Haemodynamic responses to physical activity and body posture during everyday life

OBJECTIVE: To determine the relationships between body posture and physical activity and systemic haemodynamics during everyday life. METHODS: Continuous measurements were performed in 34 subjects (16 hypertensive, 12 male), aged 49 +/- 13 (mean +/- standard deviation) years. Blood pressure (BP) was measured in the brachial artery. Physical activity and posture were measured with four accelerometers. Beat-to-beat values of systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), stroke volume (SV), cardiac output (CO) and systemic vascular resistance (SVR) were computed from the pressure waveforms. Multiple correlation coefficients (R) between activity and haemodynamic variables were computed and responses to physical activity were estimated with random regression models. RESULTS: The overall percentages of variance in SBP, DBP, HR, SV, CO and SVR explained by activity (R2) were 32, 28, 56, 44, 74, and 45%, respectively. The SBP and HR increased linearly with increasing levels of activity (19 mmHg and 30 beats/min when activity increased 90 percentiles). Other variables showed parabolic relationships. The initial decrease in SV and CO (14 ml and 0.5 l/min) and increase in DBP and SVR (9 mmHg and 2 mmHg min/l) with increasing levels of activity coincided with changes in posture (lying-sitting-standing). The subsequent SV and CO increase (23 ml and 3.7 l/min) and DBP and SVR decrease (8 mmHg and 8 mmHg min/l) coincided with changes in activity (standing-moving generally-walking). CONCLUSIONS: Our findings show that normal daily posture and activity are only moderate determinants of BP, but main determinants of HR and CO variation.     

Biological determinants of spontaneous physical activity

A decline in daily physical activity levels is clearly a major factor contributing to the current obesity epidemic affecting both developed and developing countries in the world. This escalating problem is associated with increased morbidity and mortality and reduced psychosocial health. Thus, increasing physical activity has become the strategy of choice in public health strategies to prevent obesity. Efforts to improve levels of physical activity in the population rely upon an accurate understanding of the determinants of physical activity. Most research has focused on environmental and social influences, while the potential for physical activity to be controlled by intrinsic biological processes has been largely overlooked. This review presents some of the compelling and diverse evidence that has emerged recently showing that physical activity energy expenditure is a critical factor in both the successful regulation of energy balance in normal individuals, as well as the abnormal regulation of energy balance that characterizes obesity. Although the metabolic and genetic factors involved in these regulatory processes remain mostly unidentified, some novel discoveries have been made in this area recently and these are described within this review.     

Growth and development during early manhood as determinants of prostate size in later life

BACKGROUND: Age and androgens are key determinants of benign prostate hyperplasia, but the mechanisms remain unclear. We examine the relationship between androgens and total, central, and peripheral prostate volume with a focus on early life factors. METHODS: We conducted a cross-sectional observational study of 406 community-dwelling Australian men aged 20-82 yr old without known prostate disease. Prostate zonal (total, central, and peripheral) volumes were measured by planimetric transrectal ultrasound. Participants completed questionnaires, underwent physical examination, and provided blood samples to measure total, free, and bioavailable testosterone, dihydrotestosterone, estradiol, SHBG, LH, FSH, and prostate-specific antigen. RESULTS: Prostate zonal volumes were positively associated with age, prostate-specific antigen, early onset of puberty, current height, body surface area, lean body mass, hip and waist circumference as well as recalled height and weight during puberty and adolescence but not current weight, fat mass, or body mass index. Stepwise multivariate regression modeling indicated that age and height were the only independent predictors of prostate zonal volumes. When adjusted for age and sampling time of day, the negative correlations of age-adjusted prostate zonal volumes with current blood total, free, and bioavailable testosterone and the positive correlation with blood SHBG were no longer significant. CONCLUSIONS: This study suggests that early and long-term androgen exposure may have long-acting effects on mature prostate zonal volumes, whereas relationships with current blood androgens and related hormones levels were mostly a result of confounding by age. Additional studies on the mechanism of androgen effects on late-life prostate diseases should consider lasting effects of early-life androgen exposure.     

Physical activity and determinants of physical activity in obese and non-obese children.

OBJECTIVE: To compare the physical activity (PA) patterns and the hypothesized psychosocial and environmental determinants of PA in an ethnically diverse sample of obese and non-obese middle school children. DESIGN: Cross-sectional study. SUBJECTS: One-hundred and thirty-three non-obese and 54 obese sixth grade children (mean age of 11.4+/-0.6). Obesity status determined using the age-, race- and gender-specific 95th percentile for BMI from NHANES-1. MEASUREMENTS: Objective measurements were collected of PA over a 7-day period using the CSA 7164 accelerometer: total daily counts; daily moderate (3-5.9 METs) physical activity (MPA); daily vigorous physical activity (> or =6 METs; VPA); and weekly number of 5, 10 and 20 min bouts of moderate-to-vigorous physical activity (> or =3 METs, MVPA). Self-report measures were collected of PA self-efficacy; social influences regarding PA, beliefs about PA outcomes; perceived PA levels of parents and peers, access to sporting and/or fitness equipment at home, involvement in community-based PA organizations; participation in community sports teams; and hours spent watching television or playing video games. RESULTS: Compared to their non-obese counterparts, obese children exhibited significantly lower daily accumulations of total counts, MPA and VPA as well as significantly fewer 5, 10 and 20 min bouts of MVPA. Obese children reported significantly lower levels of PA self-efficacy, were involved in significantly fewer community organizations promoting PA and were significantly less likely to report their father or male guardian as physically active. CONCLUSIONS: The results are consistent with the hypothesis that physical inactivity is an important contributing factor in the maintenance of childhood obesity. Interventions to promote PA in obese children should endeavor to boost self-efficacy perceptions regarding exercise, increase awareness of, and access to, community PA outlets, and increase parental modeling of PA.     

Differential determinants of physical daily activities in frail and nonfrail community-dwelling older adults

Background/Purpose

The purpose of this study was to determine whether or not daily activities determined by average daily steps are associated with age, gender, body mass index, fear of falling, and physical functions (locomotive function, balance function, and muscle power) in community-dwelling nonfrail and frail older adults.

Methods

This is a cross-sectional study conducted in community-dwelling older adults in Japan. Based on the Timed Up and Go (TUG) test, 629 elderly adults were divided into two groups: 515 were grouped to nonfrail elderly (TUG time less than 13.5 seconds, mean age 77.0 ± 7.2 years) and 114 to frail elderly (TUG time of 13.5 seconds or more, mean age 76.1 ± 7.5 years). Daily physical activities were determined by average daily steps measured by pedometer and four other physical function tests (10-m walk test, single-leg standing, functional reach, and five-chair stand test) were performed along with the assessment of fear of falling.

Results

Stepwise regression analysis revealed that age, gender, 10-m walk test, and single-leg standing were significant and independent determinants of the average step counts in the nonfrail elderly (R² = 0.282, p < 0.001), whereas fear of falling was the only significant and independent determinant of the average step counts in the frail elderly (R² = 0.119, p < 0.001).

Conclusion

These results indicate that differential factors may be related to daily activities depending on the level of frailty in community-dwelling older adults.     

Working in later life

The issue of work in later life has assumed increasing salience as the population (and consequently the work force) continues to age. Within 10 years, the average age of the work force will be over 40, and employers will have to face up to the fact that the pool of young school leavers is steadily shrinking.     

Social status and mortality with activity of daily living disability in later life

OBJECTIVES: The aim of this study was to assess which social status factors predispose a person to dying with activity of daily living (ADL) disability in later life. METHODS: We followed 243 deceased members of the Swiss Interdisciplinary Longitudinal Study on the Oldest Old annually up to 8 years before their deaths. Using a multilevel regression, we analyzed age at death, gender, occupational category, and geographic area as potential factors predisposing a person to ending life with ADL disability. RESULTS: Disability scores showed a substantial increase as death approached. Individuals from a lower occupational category were at higher risk of ADL disability and experienced a greater functional decline prior to death compared to those from higher occupational categories. DISCUSSION: Consistent with the cumulative disadvantage theoretical framework, the health differential between the occupational categories seems to be exacerbated prior to death.     

Time and self-identity in later life

Addressing questions raised by Kastenbaum concerning varied everyday experiences of psychological time, an attempt is made to provide a framework through which such experiences can be interpreted. Raynor's concept of time-linked sources of self-identity is elaborated to include intergenerational-linked and timeless sources of self-identity in the quest to feel good about oneself. Case examples of how eight elderly individuals viewed their futures are used in illustrating how a meaningful sense of self-identity is part of an integration of experiences over time.     

Behaviour and adaptation in later life

The implications of three revolutions in current social scientific thinking about behaviour and adaptation in later life are discussed. A demographic revolution is occurring in all countries; the number of older persons is less important than their functional impairments. A knowledge revolution has laid the basis for realistic optimism about modifiability of aging processes. A revolution in expectations about the future of aging is occurring.     

Stress and adaptation in later life

The effects of five major life events, and of three types of resources, on the physical and social-psychological adaptation of 375 participants in a longitudinal study were examined. As expected, medical events had the most impact on physical adaptation, but they had surprisingly little impact on social-psychological adaptation. Retirement had the most negative social-psychological effects, but had little effect on physical adaptation. The other three events had even less effects, although multiple events tended to cumulate in impact. Better physical resources helped only physical adaptation, and better psychological and social resources mainly helped satisfaction. It appears that most of these potential stressors have less serious long-term outcomes than the crisis orientation would suggest.