Elizabeth H. Barrington

Explanation of vigorous physical activity during two years using social learning variables.

This study examined determinants of vigorous physical activity in a community sample of adults over a 24-month period. Social learning theory predicts that causal relationships between determinants and behavior are bidirectional, and both the behavior and its influences are subject to change over time. Thus, dynamic variables were expected to account for more variance in exercise change than static baseline variables. Over 86% of respondents to the baseline mail survey completed follow-up surveys 24 months later, yielding a final sample of 1739. Two physical activity change indices were constructed that were adjusted for baseline exercise and demographic variables, so that the effects of social learning variables could be isolated. In a two-step hierarchical regression analysis, physical activity measures were regressed onto 21 static and six dynamic independent variables. Baseline self-efficacy was a significant predictor of exercise change for both dependent variables. Four dynamic social learning variables were significantly associated with both exercise change measures: self-efficacy, perceived barriers, family support, and friend support. Social learning variables accounted for 12.3-15.5% of the variance in exercise change over 24 months. The results provide strong support for bidirectional causation between behavior and determinants and suggest hypotheses to be tested in experimental studies.

Lifetime history of relapse from exercise

Most research on relapse from exercise has investigated one relapse episode following a structured program. The present study examined the patterns and determinants of the lifetime history of relapse from exercise in a community population. Subjects were 1.811 randomly selected residents of San Diego, California who completed an extensive mailed survey. Subjects reported the number of times over their lifetime that they had exercised vigorously for at least six months and then stopped exercising for at least three months. Approximately 60% of subjects reported zero relapses, 20% reported one or two relapses, and 20% reported three or more relapses. Relapse histories of current exercisers and current nonexercisers were virtually identical. The most commonly reported reason for the last relapse was injuries for both nonexecisers and exercisers. Multiple regression analyses were used to identify correlates of exercise relapse history. These data indicate that cross-sectional surveys of exercise behavior are inadequate to characterize exercise behavior in a population, and injuries are probably a major cause of relapse.

Correlates of Change in Walking for Exercise: An Exploratory Analysis

This study was designed to identify correlates of change in walking for exercise. Respondents to a random sample mailed exercise survey were asked to complete a follow-up questionnaire 24 months after the first. Responses were obtained from 1,739 adults, reflecting an 86.6% return rate. Nonrespondents did not differ from respondents for baseline level of walking for exercise. Respondents overrepresented Caucasian and middle to high education (or income) adults. Residualized measures of change in walking for exercise served as the dependent variable, adjusted for baseline walking. Similarly, key independent variables, subject to change over time, were included after residualization. At both baseline and 24 months follow-up, adults walked for exercise an average of just under 1 hour per week, and 23.5% of the initially active adults ceased walking for exercise at 2 years. Multiple regression analyses explained more variance in walking for exercise among women than men. Change in dynamic variables such as friends support and vigorous physical activity accounted for most of the explained variance. Results suggest that dynamic variables may need to be sustained to maintain walking for exercise. The limited explained variance suggests that more precise measures and additional determinants of walking for exercise need to be identified.

Cocaine and methamphetamine: Differential addiction rates

Clients admitted to treatment centers for stimulant addiction were categorized as either regular users of cocaine or of methamphetamine based on an algorithm involving 5 specific criteria. A subsample consisting of 90 regular users of cocaine and nonusers of methamphetamine, and 39 regular users of methamphetamine and nonusers of cocaine, was selected for comparison. Analyses showed that, when compared with cocaine users, the methamphetamine users exhibited a shorter period of time from 1st use to regular use (period of initial use) and from 1st use to treatment entry (period of pretreatment use). Relative to cocaine use, the use of methamphetamine appears to induce a faster rate of progression toward regular use and subsequent need for treatment.

Illness, injury, and correlates of aerobic exercise and walking : a community study

This study explores differences in exercise and walking behavior among subjects who reported temporary or long-term illnesses or injuries serious enough to have limited physical activities. The study is primarily concerned with specifying similarities and differences in correlates of vigorous exercise and walking among illness/injury groups in comparison to a healthy sample. Subjects in the analysis (N = 2,053) were drawn from a multiwave mailed survey of a probability sampling of the adult population residing in households in San Diego, California. Although differences were found in correlates of walking and vigorous exercise among the groups, self-efficacy, the belief that one is able to perform specific activities, was the most powerful and statistically significant correlate of both walking and vigorous exercise among all groups.

Illness, injury, and correlates of aerobic exercise and walking: a community study

This study explores differences in exercise and walking behavior among subjects who reported temporary or long-term illnesses or injuries serious enough to have limited physical activities. The study is primarily concerned with specifying similarities and differences in correlates of vigorous exercise and walking among illness/injury groups in comparison to a healthy sample. Subjects in the analysis (N = 2,053) were drawn from a multiwave mailed survey of a probability sampling of the adult population residing in households in San Diego, California. Although differences were found in correlates of walking and vigorous exercise among the groups, self-efficacy, the belief that one is able to perform specific activities, was the most powerful and statistically significant correlate of both walking and vigorous exercise among all groups.