The aging process leads to adverse changes in body composition (increases in fat mass and decreases in skeletal muscle mass), declines in physical function (PF), and ultimately increased risk for disability and loss of independence. Specific components of body composition or muscle capacity (strength and power) may be useful in predicting PF; however, findings have been mixed regarding the most salient predictor of PF. The development of a conceptual model potentially aids in understanding the interrelated factors contributing to PF with the factors of interest being physical activity, body composition, and muscle capacity. This article also highlights sex differences in these domains. Finally, factors known to affect PF, such as sleep, depression, fatigue, and self-efficacy, are discussed. Development of a comprehensive conceptual model is needed to better characterize the most salient factors contributing to PF and to subsequently inform the development of interventions to reduce physical disability in older adults.
Anne O. Brady, Chad R. Straight, and Ellen M. Evans
Christie L. Ward, Rudy J. Valentine, and Ellen M. Evans
Adiposity, lean mass, and physical activity (PA) are known to influence physical function in older adults, although the independent influences are not completely characterized. Older adults (N = 156, M age = 68.9 ± 6.7 yr, 85 men) were assessed for body composition via dual-energy X-ray absorptiometry, PA by accelerometer, and physical function via timed up-and-go (UP&GO), 30-s chair stand, 6-min walk (6-min WALK), and Star-Excursion Balance Test. In the absence of percentage-body-fat by PA interactions (p > .05), main effects existed such that a higher percentage body fat was associated with poorer performance in UP&GO, 30-s chair stand, and 6-min WALK (p < .05). No significant main effects were found for PA and functional performance. Adiposity explains 4.6–11.4% in physical functional variance (p < .05). Preventing increases in adiposity with age may help older adults maintain functional independence.
Kathryn E. Wilson, Bhibha M. Das, Ellen M. Evans, and Rodney K. Dishman
A positive association between physical activity and mental health is well established, particularly for lower symptoms of depression and anxiety among active adults. However, it is unclear whether the association is influenced by personality, which might moderate or otherwise explain the association. In addition, past studies have not confirmed the association using an objective measure of physical activity.
Our objective was to examine whether Extraversion and Neuroticism influence the association between mental health and physical activity measured by convergent self-reports and an accelerometer.
Structural equation modeling was used to test competing models of the relationships between personality, physical activity, and mental health in a sample of female undergraduates.
In bivariate analysis, mental health was negatively related to Neuroticism and positively related to Extraversion, self-reported physical activity (which was related only to Extraversion, positively), and objective physical activity (which was related only to Neuroticism, negatively). In structural equation modeling, a 3-way interaction indicated that objective physical activity and mental health were unrelated in extraverts, but related positively in neurotic-introverts and negatively in stable-introverts.
Higher levels of physical activity were associated with better mental health only in neurotic-introverts, who are at higher risk for mental health problems.
Eric C. Freese, Rachelle M. Acitelli, Nicholas H. Gist, Kirk J. Cureton, Ellen M. Evans, and Patrick J. O’Connor
The purpose of this investigation was to determine whether 6 weeks of sprint interval training (SIT) is associated with changes in mood and perceived health in women at risk for developing metabolic syndrome (MetS). Physically inactive women (30–65 years) were randomized to 6 weeks of nutrition meetings and SIT (n = 23; 3 bouts/week of 4–8 30-s cycle sprints with 4-min recovery) or a nonexercise control condition (CON; n = 24). Before and after the 6-week intervention, perceived health status and mood were assessed. Clinically relevant increases in role-physical scores (ES = 0.64) and vitality (ES = 0.52) were found after 6 weeks of SIT compared with a nonexercise control group. For middle-aged women at risk for MetS, it is concluded that high-intensity, low-volume SIT (1) increases feelings of vitality and perceptions of having fewer physical limitations and (2) does not induce mood disturbances as occurs with high-volume, high-intensity training.
Erika Rees-Punia, Charles E. Matthews, Ellen M. Evans, Sarah K. Keadle, Rebecca L. Anderson, Jennifer L. Gay, Michael D. Schmidt, Susan M. Gapstur, and Alpa V. Patel
This study examined the test-retest reliability and criterion validity of light (LPA), moderate (MPA), vigorous (VPA), and moderate-to-vigorous (MVPA) physical activity survey items in a subset of participants from a large prospective cohort. Participants included 423 women and 290 men aged 31–72 years in the Cancer Prevention Study-3 (CPS-3). Information on physical activity (PA) was collected using two different surveys: one survey which captures all activity performed during a typical 24-hour period in broad categories (24-hour survey), and a more detailed survey focused primarily on leisure-time PA (LTPA survey). One-year reliability was assessed by computing Spearman correlation coefficients between responses from pre- and post-study periods for both surveys. Validity was assessed by comparing survey-estimated PA with accelerometry, seven-day diaries, and a latent variable representing ‘true’ PA estimated through the method of triads. Reliability was considered acceptable for most items on the LTPA survey (range ρ = 0.45–0.92) and the 24-hour survey (range ρ = 0.37–0.61). LPA validity coefficients were higher for the 24-hour survey, while MPA, VPA, and MVPA coefficients were higher for the LTPA survey. Study results suggest that both CPS-3 PA surveys are suitable for ranking or classifying participants in our population according to overall PA category or intensity-specific activity level.