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  • Author: Ronald C. Plotnikoff x
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Ronald C. Plotnikoff, Klaus Gebel and David Revalds Lubans

Background:

According to social-cognitive theory (SCT), self-efficacy affects health behavior both directly and indirectly by influencing how individuals perceive their environment. This study examines whether perceptions of home and school environment mediate the association between self-efficacy and physical activity (PA) and sedentary behavior in adolescent girls.

Methods:

Baseline data from the Nutrition and Enjoyable Activity for Teen Girls (NEAT) was used for this study. Grade 8 female students (n = 357) were recruited from 12 secondary schools located in low-income communities in the Hunter Region, New South Wales, Australia. PA was assessed using accelerometers, and sedentary behavior by self-report and accelerometers. Self-reported measures were used for perceived home and school environment and self-efficacy. Multilevel regression models were calculated to determine if the perceived environment mediated the relationship between self-efficacy with both PA and sedentary behavior.

Results:

The perceptions of the school and home environment did not mediate the relationship between PA self-efficacy and PA behavior or sedentary behavior.

Conclusion:

The mediated models were not supported for PA or sedentary behavior. However, other results of this paper may be helpful for future theory development and practice. More research is needed to understand behaviors in unique populations such as this.

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John C. Spence, Chris M. Blanchard, Marianne Clark, Ronald C. Plotnikoff, Kate E. Storey and Linda McCargar

Background:

The purposes of this study were to determine if a) gender moderated the relationship between self-efficacy and physical activity (PA) among youth in Alberta, Canada, and, alternatively b) if self-efficacy mediated the relationship between gender and PA.

Methods:

A novel web-based tool was used to survey a regionally diverse sample of 4779 students (boys = 2222, girls = 2557) from 117 schools in grades 7 to 10 (mean age = 13.64 yrs.). Among other variables, students were asked about their PA and self-efficacy for participating in PA.

Results:

Based upon a series of multilevel analyses, self-efficacy was found to be a significantly stronger correlate of PA for girls. But, boys had significantly higher self-efficacy compared with girls, which resulted in significantly more PA.

Conclusions:

Findings suggest self-efficacy is an important correlate of PA among adolescent girls but that boys are more physically active because they have more self-efficacy for PA.

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Fabiola E. Aparicio-Ting, Christine M. Friedenreich, Karen A. Kopciuk, Ronald C. Plotnikoff and Heather E. Bryant

Background:

Little is known about the intrapersonal and social factors associated with sufficient physical activity (PA) for cancer prevention, which is greater than for cardiovascular health.

Methods:

1087 and 1684 randomly selected men and women, age 35–64, completed self-administered questionnaires on PA behavior and psycho-social characteristics. Using gender-stratified logistic regression, we investigated correlates of compliance with Canadian Society for Exercise Physiology PA guidelines for general health (150 min/wk), and the American Cancer Society (ACS; 225 min/wk) and World Cancer Research Fund/American Institute for Cancer Research (WCRF/AIRC; 420 min/wk) guidelines for cancer prevention.

Results:

Only 39% and 19% of men and women met ACS and WCRF/AICR guidelines, respectively. Self-efficacy, scheduling PA and friend social support were positively correlated with recommended PA for cancer prevention. In men, poor self-rated health and perceived negative outcomes were negatively correlated and hypertension was positively correlated with meeting cancer prevention guidelines. For women, not being married and having a companion for PA were positively correlated with meeting cancer prevention guidelines.

Conclusions:

Few adults participate in sufficient PA for cancer risk reduction. Multidimensional public health strategies that incorporate intrapersonal and social factors and are tailored for each gender are needed to promote PA for cancer prevention.

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Adam B. Lloyd, David R. Lubans, Ronald C. Plotnikoff and Philip J. Morgan

Background:

This study examined potential parenting-related mediators of children’s physical activity and dietary behavior change in the Healthy Dads, Healthy Kids (HDHK) community program.

Methods:

A randomized controlled trial was conducted with 45 overweight/obese (mean [SD] age = 39.8 [5.4] years; BMI = 32.4 [3.8]) fathers and their children (n = 77; 58% boys; mean [SD] age = 7.7 [2.5] years). Families were randomized to either the HDHK program or wait-list control group. The program involved 7 sessions. Fathers and their children were assessed at baseline and at 14 weeks for physical activity (pedometery) and core food intake (Questionnaire). Fathers’ lifestyle-related parenting practices included; self-efficacy, beliefs, modeling, logistic support, rules, cophysical activity, shared mealtime frequency and intentions.

Results:

Significant intervention effects were found for cophysical activity and modeling physical activity. Cophysical activity mediated children’s physical activity in the intervention (‘mediated effect,’ AB = 653, 95% CI = 4–2050) and was responsible for 59.5% of the intervention effect. Fathers’ beliefs mediated children’s percent energy from core foods (AB = 1.51, 95% CI = 0.05–5.55) and accounted for 72.9% of the intervention effect.

Conclusions:

Participation in the HDHK program positively impacted on fathers’ cophysical activity with their child and beliefs about healthy eating which mediated changes in children’s diet and physical activity behaviors.

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Alyce T. Barnes, Ronald C. Plotnikoff, Clare E. Collins and Philip J. Morgan

Background:

The aim was to assess the feasibility and preliminary efficacy of a community-based physical activity (PA) intervention targeting mothers and daughters.

Methods:

A randomized controlled trial of 48 primary school-aged girls and their 40 mothers were randomized to (i) Mothers And Daughters Exercising for Life (MADE4Life) (n = 21 mothers, n = 25 daughters) or (ii) wait-list control (n = 19 mothers, n = 23 daughters). The 8-week program involved 8 sessions; 25-minute separate mothers and daughters education sessions and 60-minutes PA together. Assessments were at baseline, postintervention and 3-month postintervention. Primary outcome measure was daughters’ moderateto-vigorous physical activity (MVPA) (accelerometer). Secondary outcomes included accelerometer-assessed light/moderate/vigorous PA, BMI, waist circumference, body composition, blood pressure, resting heart rate, sedentary behaviors and mothers’ self-reported PA, parenting measures, and cognitions. Intention-to-treat analysis used linear mixed models.

Results:

Recruitment and retention goals were exceeded. Attendance rates, program acceptability and satisfaction were high. There was no significant group-by-time effect for daughters’ %MVPA (–0.08; 95%CI –1.49, 1.33, d = –0.03) or other secondary outcomes for girls (postintervention range d = 0.01 to –0.46). Significant intervention effects were found for mothers’ %VPA (P = .04, d = 0.25) and role modeling (P = .02, d = 0.66).

Conclusion:

MADE4Life was both feasible and acceptable. Although very small effect sizes were found for the daughters, significant changes were seen for mothers (d = 0.25 to 0.66). Future fully powered trials targeting PA in mothers and daughters is warranted.

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Deborah L. Dewar, David Revalds Lubans, Philip James Morgan and Ronald C. Plotnikoff

Background:

This study aimed to develop and evaluate the construct validity and reliability of modernized social cognitive measures relating to physical activity behaviors in adolescents.

Methods:

An instrument was developed based on constructs from Bandura’s Social Cognitive Theory and included the following scales: self-efficacy, situation (perceived physical environment), social support, behavioral strategies, and outcome expectations and expectancies. The questionnaire was administered in a sample of 171 adolescents (age = 13.6 ± 1.2 years, females = 61%). Confirmatory factor analysis was employed to examine model-fit for each scale using multiple indices, including chi-square index, comparative-fit index (CFI), goodness-of-fit index (GFI), and the root mean square error of approximation (RMSEA). Reliability properties were also examined (ICC and Cronbach’s alpha).

Results:

Each scale represented a statistically sound measure: fit indices indicated each model to be an adequate-to-exact fit to the data; internal consistency was acceptable to good (α = 0.63−0.79); rank order repeatability was strong (ICC = 0.82−0.91).

Conclusions:

Results support the validity and reliability of social cognitive scales relating to physical activity among adolescents. As such, the developed scales have utility for the identification of potential social cognitive correlates of youth physical activity, mediators of physical activity behavior changes and the testing of theoretical models based on Social Cognitive Theory.

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Steven T. Johnson, Clark Mundt, Weiyu Qiu, Allison Soprovich, Lisa Wozniak, Ronald C. Plotnikoff and Jeffrey A. Johnson

Objective:

To determine the effectiveness of an exercise specialist led lifestyle program for adults with type 2 diabetes in primary care.

Methods:

Eligible participants from 4 primary care networks in Alberta, Canada were assigned to either a lifestyle program or a control group. The program targeted increased daily walking through individualized daily pedometer step goals for the first 3 months and brisk walking speed, along with substitution of low-relative to high-glycemic index foods over the next 3 months. The outcomes were daily steps, diet, and clinical markers, and were compared using random effects models.

Results:

198 participants were enrolled (102 in the intervention and 96 in the control). For all participants, (51% were women), mean age 59.5 (SD 8.3) years, A1c 6.8% (SD 1.1), BMI 33.6 kg/m2 (SD 6.5), systolic BP 125.6 mmHg (SD 16.2), glycemic index 51.7 (4.6), daily steps 5879 (SD 3130). Daily steps increased for the intervention compared with the control at 3-months (1292 [SD 2698] vs. 418 [SD 2458] and 6-months (1481 [SD 2631] vs. 336 [SD 2712]; adjusted P = .002). No significant differences were observed for diet or clinical outcomes.

Conclusions:

A 6-month lifestyle program delivered in primary care by an exercise specialist can be effective for increasing daily walking among adults with recently diagnosed type 2 diabetes. This short-term increase in daily steps requires longer follow-up to estimate the potential impact on health outcomes.

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Angus A. Leahy, Narelle Eather, Jordan J. Smith, Charles H. Hillman, Philip J. Morgan, Ronald C. Plotnikoff, Michael Nilsson, Sarah A. Costigan, Michael Noetel and David R. Lubans

Purpose: This study was designed to assess the feasibility and preliminary efficacy of a teacher-facilitated high-intensity interval training intervention for older adolescents (ie, 16–18 y). Methods: Two secondary schools from New South Wales, Australia were recruited, and participants (ie, grade 11 students; 16.2 [0.4] y) were randomized at the school level to the Burn 2 Learn intervention (n = 38), or a wait-list control group (n = 30). Teachers were trained to facilitate the delivery of the novel high-intensity interval training program, which involved 3 sessions per week (∼12–20 min) for 14 weeks. A range of process measures were used to assess intervention feasibility (ie, recruitment, retention, attendance, and program satisfaction). Primary (cardiorespiratory fitness, determined using the progressive aerobic cardiovascular endurance run shuttle run test) and secondary outcomes were assessed at baseline and posttest (14-wk). Results: Sixty-eight grade 11 students were recruited at baseline (85% of target sample), 61 participants completed posttest assessments (90% retention) and on average, participants performed 1.9 sessions per week. Overall, teachers (4.0/5) and students (4.0/5) were satisfied with the Burn 2 Learn program. Group by time effects were observed for cardiorespiratory fitness (8.9 laps; 95% confidence intervals, 1.7–16.2) and a selection of secondary outcomes. Conclusion: This study provides evidence for the feasibility and preliminary efficacy of a teacher-facilitated high-intensity interval training intervention for older adolescents.

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Ronald C. Plotnikoff, Michael A. Pickering, Nicole Glenn, Sandra L. Doze, Melissa L. Reinbold-Matthews, Laura J. McLeod, David C. W. Lau, Gordon H. Fick, Steven T. Johnson and Laura Flaman

Background:

Physical activity (PA) is a cornerstone in the management of type 2 diabetes (T2DM). This pilot investigation explores the effects of a standard diabetes education program compared with a supplemental PA intervention on diabetes-related health outcomes.

Methods:

Using a prospective 2-armed design, 96 adults with T2DM were randomly assigned to either standard care (diabetes education program; n = 49) or standard care supplemented with an 8-week, individualized-counseling and community-based PA component (n = 47). Measurements were taken at baseline, 3, 6, and 12 months. Primary outcomes were changes in PA (self-report) and HbA1c. Between group changes were compared using analysis of covariance (ANCOVA) and changes over time using repeated-measures ANOVA.

Results:

In comparison with standard care, the supplemental group demonstrated an increase in PA (Ps < 0.01) and cardiorespiratory fitness (Ps < 0.05) from baseline to all follow-up time-points. HbA1c levels declined (P < .05) from baseline to all time points in the standard care group. Reduction in cholesterol-ratio (P < .01), increase in HDL (P < .05), and reductions in blood pressure, resting heart rate and BMI (approaching statistical significance Ps < 0.10) were also reported for both groups.

Conclusions:

PA counseling in addition to standard care is effective for promoting PA behavior change and positive health-related outcomes among individuals with T2DM.