Using Rasch modeling to re-evaluate three scales related to physical activity: enjoyment, perceived benefits and perceived barriers.

Studies suggest that enjoyment, perceived benefits and perceived barriers may be important mediators of physical activity. However, the psychometric properties of these scales have not been assessed using Rasch modeling. The purpose of this study was to use Rasch modeling to evaluate the properties of three scales commonly used in physical activity studies: the Physical Activity Enjoyment Scale, the Benefits of Physical Activity Scale and the Barriers to Physical Activity Scale. The scales were administered to 378 healthy adults, aged 25-75 years (50% women, 62% Whites), at the baseline assessment for a lifestyle physical activity intervention trial. The ConQuest software was used to assess model fit, item difficulty, item functioning and standard error of measurement. For all scales, the partial credit model fit the data. Item content of one scale did not adequately cover all respondents. Response options of each scale were not targeting respondents appropriately, and standard error of measurement varied across the total score continuum of each scale. These findings indicate that each scale's effectiveness at detecting differences among individuals may be limited unless changes in scale content and response format are made.

Does adherence to a lifestyle physical activity intervention predict changes in physical activity?

This study examined whether adherence to a lifestyle physical activity intervention predicted weekly participation in at least 150 min of moderate to vigorous physical activity among 244 sedentary healthy adults. Structural equation modeling was used to assess the association between adherence and physical activity. Markers of adherence were attendance, homework completion, and self-monitoring for a group-based intervention and telephone call completion, homework completion, and self-monitoring for a telephone and mail-delivered intervention. For both interventions, adherence significantly predicted moderate to vigorous physical activity. Adherence to lifestyle physical activity interventions ought to be encouraged to increase the likelihood that participants will engage in an adequate amount of physical activity for health benefits to occur.

Field evaluation of energy expenditure from continuous and intermittent walking in women.

RATIONALE: Recent physical activity recommendations suggest that comparable amounts of prescribed physical activity, done as a single continuous bout or as a set of intermittent bouts, will produce equal amounts of energy expenditure (EE) during the prescribed activity as well as throughout the day. HYPOTHESES: In a field setting, we tested two hypotheses: (1) continuous and intermittent walking conditions will result in significantly greater total daily EE than a control condition, and (2) continuous and intermittent walking conditions will result in similar total daily METHODS: Thirty women (mean age [yr] = 43.7+/-5.8; mean body mass index [kg x m(-2)]= 24.7+/-4.0) participated in a repeated-measures design so that each woman participated in three walking conditions on successive days of the week: a single 30-min brisk walk (continuous): three 10-min brisk walks (intermittent); and no activity (control). Throughout the study protocol, women wore a TRITRAC-R3D accelerometer programmed to estimate EE in 2-min intervals. RESULTS: Mean total EE estimates (kcal) for the three walking conditions were as follows: continuous: 2181+/-308; intermittent: 2121+/-305; and control: 1948+/-270. A repeated-measures analysis of variance omnibus test indicated that EE differed significantly by experimental condition [F(2,58) = 40.2, P < 0.001). To test the first hypothesis, contrasts were examined revealing that EE in the continuous and intermittent conditions was significantly greater than EE in the control condition [F(1,29) = 58.2, P < 0.001]. To test the second hypothesis, contrasts revealed that EE in the continuous condition was significantly greater than EE in the intermittent condition [F(1,29) = 7.0, P = 0.013]. CONCLUSION: For the purposes of total EE, selecting a continuous mode of walking may offer additional benefit over an intermittent mode, given the same total prescribed duration.

Perceptions of sedentary African-American women about continuous versus intermittent walking.

To meet current physical activity recommendations, a person may chose to adopt a continuous or an intermittent physical activity program, as long as they accumulate 30 minutes of moderate-intensity physical activity most days of the week. Sixty-four sedentary African-American women were surveyed to assess whether perceptions about continuous and intermittent walking programs differed. Specifically, we assessed whether perceptions of self-efficacy, outcome expectations, social support, and the environment varied with respect to walking programs. Results indicated that the women perceived higher self-efficacy for the intermittent walking program and associated this program with more favorable environmental factors (p < .05). However, they expected greater benefits from the continuous walking program (p < .05). Overall, 65% of the women reported that they would prefer to adopt the continuous walking program.

Reliability, validity, and methodological issues in assessing physical activity in a cross-cultural setting.

In summary, to complement the issues raised in Dr. Kriska's paper, this paper identified a number of methodological issues that researchers need to address before valid cross-cultural comparisons can be performed (see summary of issues and proposed actions for researchers in Table 1). In addition, this paper cautions us to interpret published findings in light of the methodological issues that were raised in this paper. This paper selectively addressed some methodological issues and leaves ample room for other researchers to think of other important issues. Many of the issues raised in this paper are related to the use of questionnaires to make cross-cultural comparisons. However, many of the methodological issues presented in this paper apply to other methods of assessing physical activity behaviors. As a final remark, I do want to acknowledge that other methods used to measure physical activity (including activity monitor) provide valuable but different information than questionnaires. It remains that in large-scale epidemiological studies, questionnaires are often the most practical instrument to use, and given the errors associated with questionnaires, we need to consider whether questionnaires are better at measuring physical activity behaviors at the group level or individual level.

Detecting bouts of physical activity in a field setting.

The purposes of this study were to assess the TRITRAC and CSA for: (a) interaccelerometer agreement; (b) agreement in detecting patterns of moderate-intensity physical activity; and (c) agreement in detecting walking patterns recorded in a diary. Thirty-one women wore both the TRITRAC and CSA accelerometers for three consecutive days. Interaccelerometer agreement (measured with generalizability coefficients) ranged from .88 to .99. In total, 71.3% of the accelerometers' patterns agreed in length, with CSA patterns being on average significantly longer. Interaccelerometer agreement in detecting patterns of brisk walking, as recorded in a diary, was comparable (69.4%). Interaccelerometer discrepancies may be related in part to the threshold employed by each instrument for classifying moderate intensity patterns.

Validity of scales measuring the psychosocial determinants of HIV/STD-related risk behavior in adolescents.

We examined the content, construct and concurrent validity of scales to assess beliefs and self-efficacy related to adolescents' sexual risk behavior. We addressed content validity in the scale development process by drawing on literature and theory, and by pre-testing items with focus groups. We used confirmatory factor analysis of two models, an intercourse involvement model and a condom use model, to assess construct validity. The final intercourse involvement model included three scales: norms about sexual intercourse, attitudes about sexual intercourse and self-efficacy in refusing sex. The final condom use model included five scales: norms about condoms, attitudes about condom use, self-efficacy in communicating about condoms, self-efficacy in buying/using condoms and barriers to condom use. After two alterations to the models, the chi 2 and other indices indicated that the data fit the models well. Supporting the concurrent validity of the scales, high school students who had never had sexual intercourse had more negative attitudes toward sexual intercourse among teenagers, perceived norms toward sexual intercourse among teenagers to be more negative and expressed greater self-efficacy in refusing sex than did those who had experienced sexual intercourse. Consistent condom users had more positive attitudes and norms about condoms, had higher self-efficacy in communicating about and buying/using condoms, and perceived fewer barriers to condom purchase and use than did inconsistent condom users.

Evaluation of a skin cancer prevention module for nurses: change in knowledge, self-efficacy, and attitudes.

PURPOSE: The purpose of this study was to evaluate the effectiveness of a 1-week didactic and clinical skin cancer prevention training module. The evaluation assessed both the immediate and the 3-month effects of the module on nurse participants. In addition, this study assessed whether the module had any secondary effects on skin cancer practices, including perceived support from colleagues, resources, time, and perceived responsibility to conduct skin cancer screening activities and education. METHODS: A quasi-experimental design with 32 intervention and 87 comparison subjects was employed. Instruments developed and validated specifically for this study were used to assess knowledge, self-efficacy, priority of skin cancer, and organizational level constructs. RESULTS: The findings indicate that the module significantly increased general and prevention knowledge as well as screening ability; the increase was stable over time. The module was also found to improve self-efficacy to screen and to educate. There was no effect on the organizational-level constructs. CONCLUSIONS: Baseline knowledge assessments validated other studies indicating that nurses need more education about skin cancer. Despite promising results from program participants, system-level barriers could impose substantial barriers to implementation in health care practice. Knowledgeable nurses must educate their colleagues, their supervisors, and the public about the priority of skin cancer screening and develop strategies for creating organizational change to increase the likelihood that screening and patient education will occur for people at risk for skin cancer.

Assessing physical activity among minority women: focus group results.

Focus group findings indicate a need to develop physical activity surveys that are more relevant for women, that include well-defined, inoffensive terminology, and that improve recall of unstructured and intermittent physical activities.

Measuring physical activity in midlife, older, and minority women: issues from an expert panel.

This article summarizes the findings of an exploratory meeting of 53 experts brought together under the aegis of the Women's Health Initiative to identify important issues related to measuring physical activity in minority women, women in midlife (aged 40-75), and older women (aged > 75). The findings address five areas, three dealing with measurement and two concerning the design of surveys: (1) population characteristics to consider when measuring the physical activity of women and minority populations, (2) activity dimensions relevant to physical activity surveys, (3) measuring moderate and intermittent activities, (4) designing and administering physical activity surveys for older and minority women, and (5) establishing the reliability and validity of such physical activity surveys. Although the focus of the expert panel meeting was on identifying issues related to the measurement of physical activity in women, many issues summarized here can be generalized to children and men. The panel's findings concerning measuring physical activity are timely, as they directly bear on the challenges associated with the physical activity guidelines jointly issued by the Centers for Disease Control and Prevention and the American College of Sports Medicine and the recommendations made in the Surgeon General's 1996 report, Physical Activity and Health.

Behavior of boys in kindergarten and the onset of substance use during adolescence.

BACKGROUND: The purpose of this study was to assess the usefulness of personality dimensions measured at ages 6 and 10 years in predicting early onset of cigarette smoking, alcohol abuse, and other drug use in boys. In addition, the stability of the prediction between the measurements at ages 6 and 10 years was investigated. METHODS: Data from a large longitudinal study of boys were used to assess the relation between childhood personality and the onset of substance use from 10 to 15 years of age. Childhood personalities were assessed by teachers' ratings of behaviors. Self-reports of smoking cigarettes, getting drunk, and using other drugs provided the measurement of substance use. Discrete-time survival analysis was used for the statistical analyses. RESULTS: High novelty-seeking and low harm avoidance significantly predict early onset of substance use (eg, cigarettes, alcohol, and other drugs), but reward dependence was unrelated to any of the outcomes studied. The results also indicated that either set of predictors (ie, the personality dimensions measured at ages 6 and 10 years) could be used to predict onset of cigarette smoking, getting drunk, and other drug use, because the power of prediction was similar between the measurements at ages 6 and 10 years. CONCLUSIONS: High novelty-seeking and low harm avoidance lead to early onset of substance use in boys. The stability of the prediction between ages 6 and 10 years suggests that the kindergarten assessments may be used for preventive efforts at school entry instead of waiting until early adolescence.

A bimodal preventive intervention for disruptive kindergarten boys: its impact through mid-adolescence.

Disruptive kindergarten boys from inner-city low socioeconomic neighborhood schools were randomly allocated to a preventive intervention and control condition. The 2-year prevention program included a home-based parent training component and a school-based social skills training component. Participants were followed up to mid-adolescence. Results indicated that a significantly greater percentage of treated boys remained in an age-appropriate regular classroom up to the end of elementary school and that the treated boys reported significantly less delinquent behaviors at yearly assessments from 10 to 15 years old, compared with controls. The preventive intervention appeared to have a significant long-term impact on the social development of the disruptive kindergarten boys. Earlier and more intensive intervention may be necessary for some cases, whereas for all disruptive boys, booster sessions between 12 and 15 years of age are recommended.

Individual and peer characteristics in predicting boys' early onset of substance abuse: a seven-year longitudinal study.

Early onset of substance abuse is a clear marker for future maladjustment in adolescents. The present study employed data originating from 755 6-year-old boys from low SES neighborhoods, who were followed through age 13, to predict this marker, 3 models were tested using LISREL analyses to determine whether individual characteristics and/or peer influences were linked to subsequent substance abuse. Individual characteristics consisted of fighting, hyperactivity, oppositional behaviors, and likability. Peer influences referred to mutual friends' characteristics (aggressiveness and likability). Data were obtained from 3 different sources: teacher ratings, peer ratings, and self-reports. Results were replicated at ages 10, 11, and 12 years with 3 subsamples of the original sample and indicated that individual characteristics, more than friends' deviance, are pivotal in the development of substance abuse. This finding is consistent with results from other longitudinal studies involving children from a variety of cultural backgrounds. It suggests that prevention programs should target individual characteristics and begin at an early age.

Biomechanical analysis of wheelchair propulsion for various seating positions.

The pattern of propulsion was investigated for five male paraplegics in six seating positions. The positions consisted of a combination of three horizontal rear-wheel positions at two seating heights on a single-purpose-built racing wheelchair. To simulate wheelchair propulsion in the laboratory, the wheelchair was mounted on high rotational inertia rollers. For three trials at each seating position, the subjects propelled the designed wheelchair at 60 percent of their maximal speed, which was determined at the beginning of the test session. At each trial, the propulsion technique of the subject was filmed at 50 Hz with a high-speed camera for one cycle, and the raw electromyographic (EMG) signal of the biceps, brachii, triceps brachii, pectoralis major, deltoid anterior, and deltoid posterior muscles were simultaneously recorded for three consecutive cycles. The digitized film data were used to compute the angular kinematics of the upper body, while the EMG signals were processed to yield the linear envelope (LE EMG) and the integrated EMG (IEMG) of each muscle. The kinematic analysis revealed that the joint motions of the upper limbs were smoother for the Low positions-since they reached extension in a sequence (wrist, shoulder, and elbow), when compared to the High positions. Also, the elbow angular velocity slopes were found to be less abrupt for the Backward-Low position. It was observed that in lowering the seat position, less IEMG was recorded and the degrees of contact were lengthened. Among the seat positions evaluated, the Backward-Low position had the lowest overall IEMG and the Middle-Low position had the lowest pushing frequency. It was found that a change in seat position caused more variation in the IEMG for the triceps brachii, pectoralis major, and deltoid posterior. The trunk angular momentum was not found to be affected by a change in seat position which may be related to the variability among the subject's technique of propulsion or to a posture compensation.