Karen J. Calfas

Assessing Perceived Physical Environmental Variables that May Influence Physical Activity

The present study evaluated a measure of perceived physical environments that may influence physical activity. Forty-three self-report items were used to assess environmental variables at homes, in neighborhoods, or on frequently traveled routes. The presence of facilitators of (e.g., equipment, programs, attractive surroundings) and barriers to (e.g., high crime) physical activity was assessed. In 110 college students, test-retest reliabilities were .89 for the home equipment scale, .68 for the neighborhood scale, and .80 for the convenient facilities scale. Home equipment and convenient facilities scales were correlated with self-reported physical activity. In multiple regression analyses, the only significant association, after adjusting for neighborhood socioeconomic status, was home equipment with strength exercise. Further research is needed to identify other environmental characteristics that may influence physical activity.

Assessment of Physical Activity with the Computer Science and Applications, Inc., Accelerometer: Laboratory versus Field Validation

Abstract Our purpose was to compare the validity of the Computer Science and Applications, (CSA) Inc., accelerometer in laboratory and field settings and establish CSA count ranges for light, moderate, and vigorous physical activity. Validity was determined in 60 adults during treadmill exercise, using oxygen consumption (VO2) as the criterion measure, while 30 adults walked and jogged outdoors on a 400-m track. The relationship between CSA counts and VO2 was linear (R2 = .89 SEE = 3.72 ml. kg1. min1), as was the relationship between velocity and counts in the field (R2 = .89, SEE = 0.89 mi. hr1). However, significant differences were found (p < .05) between laboratory and field measures of CSA counts for light and vigorous intensity. We conclude that the CSA can be used to quantify walking and jogging outdoors on level ground; however, laboratory equations may not be appropriate for use in field settings, particularly for light and vigorous activity.

Psychosocial and Environmental Correlates of Adolescent Sedentary Behaviors

Objective. To determine correlates of sedentary behaviors in adolescents through the examination of psychosocial and environmental variables. Method. The study used a cross-sectional design to evaluate an ethnically diverse clinic-based sample of 878 adolescents who were 11 to 15 years old. Bivariate and multivariate analyses were stratified by gender to assess correlates of sedentary behaviors occurring on the most recent nonschool day (television viewing, computer video games, sitting listening to music, and talking on the phone). Results. For girls, age, family support, television/video rules, and hills in the neighborhood were associated with sedentary behaviors. Furthermore, psychological constructs such as self-efficacy, enjoyment, change strategies, and pros and cons of change emerged as correlates of sedentary behaviors. A moderator effect revealed that the proportion of girls in the low-BMI group decreased with increased self-efficacy, whereas the proportion of girls in the high-BMI group did not vary significantly by self-efficacy. For boys, age, ethnicity, BMI, cons of change, and self-efficacy were associated with sedentary behaviors. Conclusions. This study provides evidence of factors associated and not associated with adolescent sedentary behaviors. Similar to physical activity, measures of specific psychosocial constructs of sedentary behavior demonstrated important associations. The results highlight the need for additional examination of the correlates of sedentary behavior to determine which correlates are mechanisms of behavior change.

Validity, reliability, and calibration of the Tritrac accelerometer as a measure of physical activity.

PURPOSE The purposes of this study were to assess the validity and reliability of the Tritrac R3D accelerometer during treadmill walking and running and then to calibrate the instrument. METHODS The Tritrac was assessed on 60 young adults (23.4 +/- 2.9 yr) during treadmill walking and running at 3.2, 6.4, and 9.7 km x h(-1). The calibration was carried out by identifying ranges of Tritrac raw data (vector magnitude) values corresponding to light (2-3.9 MET), moderate (4-7 MET), and vigorous (>7 MET) physical activity. Energy expenditure (EE), measured by indirect calorimetry, served as the criterion measure. RESULTS Interinstrument intraclass reliability coefficients for Tritracs worn on the right and left hip ranged from 0.73-0.87, while intersession coefficients demonstrated high reliability for all speeds (R = 0.87-0.92). Paired t-tests comparing mean accelerometer counts at 6.4 km x h(-1), 0% grade (2647 +/- 456), and 6.4 km x h(-1), 5% grade (2635 +/- 435) demonstrated no significant difference (P > 0.05). Mean differences between EE measured by indirect calorimetry and that estimated by the Tritrac ranged from 0.0082 kcal x kg(-1) x min(-1) at 3.2 km x h(-1) to 0.0320 kcal x kg(-1) x min(-1) at 9.7 km x h(-1), with the Tritrac consistently overestimating EE during horizontal treadmill walking. The relationship between vector magnitude and EE across all speeds was highly linear (R2 = 0.90, SEE = 0.014 kcal x kg(-1) x min(-1)), with little overlap between light, moderate, and vigorous categories. The mean vector magnitudes at 2, 4, and 7 MET were 650, 1772, and 3455, respectively. CONCLUSIONS These data indicate that the Tritrac is highly reliable from day to day and is sensitive to changes in speed but not grade. Furthermore, the Tritrac accurately distinguishes various intensities of walking and jogging on level ground. With limitations, these cut-points can be used to categorize light, moderate, and vigorous physical activity and to estimate EE.

Effects of interventions in health care settings on physical activity or cardiorespiratory fitness

INTRODUCTION This paper reviews studies of physical activity interventions in health care settings to determine effects on physical activity and/or fitness and characteristics of successful interventions. METHODS Studies testing interventions to promote physical activity in health care settings for primary prevention (patients without disease) and secondary prevention (patients with cardiovascular disease [CVD]) were identified by computerized search methods and reference lists of reviews and articles. Inclusion criteria included assignment to intervention and control groups, physical activity or cardiorespiratory fitness outcome measures, and, for the secondary prevention studies, measurement 12 or more months after randomization. The number of studies with statistically significant effects was determined overall as well as for studies testing interventions with various characteristics. RESULTS Twelve studies of primary prevention were identified, seven of which were randomized. Three of four randomized studies with short-term measurement (4 weeks to 3 months after randomization), and two of five randomized studies with long-term measurement (6 months after randomization) achieved significant effect on physical activity. Twenty-four randomized studies of CVD secondary prevention were identified; 13 achieved significant effects on activity and/or fitness at twelve or more months. Studies with measurement at two time points showed decaying effects over time, particularly if the intervention were discontinued. Successful interventions contained multiple contacts, behavioral approaches, supervised exercise, provision of equipment, and/or continuing intervention. Many studies had methodologic problems such as low follow-up rates. CONCLUSION Interventions in health care settings can increase physical activity for both primary and secondary prevention. Long-term effects are more likely with continuing intervention and multiple intervention components such as supervised exercise, provision of equipment, and behavioral approaches. Recommendations for additional research are given.

Prospective evaluation of three smoking interventions in 205 recovering alcoholics : One-year results of project SCRAP-tobacco

A total of 205 (113 male, 92 female) nonhospitalized recovering alcoholics with > 3 months of continuous abstinence from alcohol and drugs and relatively heavy tobacco dependence (Fagerstrom Tolerance Questionnaire score = 7.7; mean number of cigarettes per day, 26.8; mean number of years smoked, 24.4) were randomized to standard treatment (ST) American Lung Association quit program plus nicotine anonymous meetings (n = 70), behavioral counseling plus physical exercise (BEX; n = 72), or behavioral counseling plus nicotine gum (BNIC; n = 63). A 3 x 4 repeated measures design was used to evaluate the effectiveness of the interventions on smoking outcome at baseline, posttreatment, and 6- and 12-month follow-ups. Self-reported smoking status was verified with biochemical and informant report. Verified self-report indicated that significantly more smokers in BEX quit by posttreatment (60%) than in either BNIC (52%) or ST (31%), chi 2 (2, N = 205) = 17.85, p < .01, but not at the 6-month (29%, 27%, and 21%, respectively) or 12-month (27%, 27%, and 26%, respectively) follow-up. Only 4% (7 of 188) relapsed to alcohol or drugs. Alcohol relapse did not differ by treatment group or smoking status. Length of alcohol abstinence was not associated with smoking cessation outcome.

Self-report measures and scoring protocols affect prevalence estimates of meeting physical activity guidelines

PURPOSE Prevalence estimates of meeting the guidelines for physical activity based on various self-report measures were compared, and the effects of various scoring protocols on the estimates were evaluated. METHOD A sample of 575 university students aged 24.5 +/- 1.9 yr (56% women, 54% Euro-American) completed the Seven-Day Physical Activity Recall interview (PAR), Youth Risk Behavior Survey (YRBS), and National Health Interview Survey 1991 (NHIS). To determine the prevalence of meeting the ACSM (1990) fitness and the CDC/ACSM (1995) health-related guidelines, various scoring protocols were employed that closely approximated the recommendations. Protocols varied by whether frequency and duration or duration only were considered. For the health-related guidelines, scoring protocols also varied depending on the intensity of activities considered. RESULTS Depending on the scoring protocol and instrument used, the proportion meeting the fitness guidelines ranged from 32 to 59%. The NHIS, YRBS, and PAR resulted in significantly different proportions of those meeting the health-related guideline, ranging from 4 to 70%. CONCLUSION The type of measure as well as the scoring protocol affected prevalence estimates of meeting the physical activity guidelines. This study indicates the difficulty of comparing prevalence rates across studies using different measures.

Project GRAD: two-year outcomes of a randomized controlled physical activity intervention among young adults. Graduate Ready for Activity Daily.

INTRODUCTION Project Graduate Ready for Activity Daily evaluated a program to promote physical activity through the transition of university graduation in a randomized controlled trial. METHODS Three hundred thirty-eight university seniors participated in either a cognitive-behavioral intervention course or a knowledge-oriented general health course during the semester before graduation. Behaviorally oriented phone and mail follow-up was delivered to the intervention group for 18 months. Physical activity outcomes and mediating variables were assessed at baseline, 1 and 2 years (93% retention rate). RESULTS There were no significant intervention effects on physical activity outcomes at 2 years for either men or women. Experiential and behavioral processes of change were significantly improved for intervention women over 2 years. CONCLUSIONS Despite excellent participation in a theoretically based, well-attended intervention, few long-term effects on physical activity or its mediators were found. Additional research is needed to determine optimal interventions for physical activity and to validate or alter current behavior change theory.

Potential mediators of change in a physical activity promotion course for university students: Project GRAD.

The purpose of the study is to evaluate the performance of theoretically-derived mediators of health behavior change. Participants were university seniors (184 females; 154 males) randomly assigned to an intervention course designed to promote physical activity or to a control course. Five physical activity outcomes and nine psychosocial mediating variables were assessed at baseline and the end of the 16-week course. For women, the intervention had significant effects on five of the mediators, including self-efficacy for making time, self-efficacy for resisting relapse, social support from friends, and experiential and behavioral processes of change. Among men, the intervention improved use of behavioral processes of change but also had the unintended effect of increasing perceived barriers to activity. For women, significant contributors to regressions explaining physical activity change were social support from friends (for total activity) and change in self-efficacy for resisting relapse (for vigorous exercise). For men, significant explanatory variables included change in enjoyment (for total activity), change in self-efficacy for resisting relapse (for strength exercise), and change in benefits (for moderate intensity activity). For both sexes, there were significant findings in the unexpected direction. Across the five physical activity outcomes, hypothesized mediators were inconsistent and weak contributors to the models. Investigating mediators of behavior change has the potential to stimulate improvements in theories and interventions.

Evaluation of a University Course to Promote Physical Activity: Project GRAD

Project GRAD (Graduate Ready for Activity Daily) evaluates a university course to promote physical activity. In a randomized study, 338 university seniors participated in either an intervention or control course for academic credit, and posttest data were collected on 321. The control course was knowledge-oriented. The intervention course taught behavior change skills in weekly lectures and peer-led labs. Physical activity was assessed with 7-Day Physical Activity Recall interviews. The intervention had no significant effects on men. Among women, the intervention increased total physical activity during leisure, strengthening exercises, and flexibility exercise. This university course had the intended effects of promoting healthful patterns of physical activity among women, but no effects were observed on men, who were more active than women at baseline.