Development and exploratory cluster-randomised opportunistic trial of a theory-based intervention to enhance physical activity among adolescents

May combine two claims.

Multilevel analyses indicated that adolescents in intervention classes perceived more negative outcomes associated with current PA and reported higher coping planning.

“Multilevel analyses indicated that adolescents in the intervention classes perceived more negative outcomes associated with their current levels of physical activity (situation-outcome expectancies) and reported higher levels of coping planning.”

May combine two claims.

Trends favouring intervention were not significant for self-efficacy and approached significance for action planning.

“Trends favouring the intervention group were not significant for self-efficacy and approached significance for action planning.”

May combine two claims.

Sensitivity analysis imputing baseline PA for missing values confirmed significant group differences at Time 4 and a trend approaching significance at Time 3.

“While imputing pre-intervention baseline data for missing values naturally decreases the point estimates of effects, the sensitivity analysis confirms the significant group differences at Time 4 and the trend approaching significance at Time 3.”

May combine two claims.

Participants in the intervention group showed significantly higher increases in situation outcome expectancies and coping planning than controls.

“Participants in the intervention group showed significantly higher increases in situation outcome expectancies and coping planning than controls, i.e., they became more aware that their current levels of physical activity might not be sufficient to achieve positive outcomes and developed clearer plans about how to deal with barriers for regular PA.”

May combine two claims.

Baseline PA and sex accounted for significant variance in PA, while age did not.

“The random effects regression analyses show that baseline PA (T2: B=.33; SE=.04; p<.001; T3: B=.41; SE=.06; p<.001; T4: B=.27; SE=.05; p<.001) and sex (T2: B=52.5;SE=14.6;p<.001) both account for significant amounts of variance in PA, while age does not contribute to the equation.”

May combine two claims.

Trends for self-efficacy and action planning favoured intervention but were not significant.

“Trends for selfefficacy and action planning favour the intervention group but remain insignificant.”

May combine two claims.

The models accounted for 24.9% of variance at Time 2, 29.8% at Time 3, and 36.9% at Time 4.

“These models account for 24.9% of the variance at Time 2; 29.8% at Time 3 and 36.9% at Time 4.”

May combine two claims.

The intervention effect on moderate-to-vigorous physical activity was not statistically significant at Time 2 or Time 3.

“Time 2 | 119 | (134) | 100 | (143) | 18 | -10 | 46 | 0.202”

• Also stated in: § Limitations and future research · plain

  “Time 3 | 141 | (171) | 104 | (170) | 33 | -4 | 71 | 0.082”

May combine two claims.

Action planning and coping planning both correlated significantly with physical activity.

“Both measures show significant correlations with physical activity”

May combine two claims.

Theory-based interventions allow testing whether the intervention modifies hypothesised determinants and whether those changes mediate behaviour change.

“Moreover, applications of theory-based interventions present an opportunity to test if an intervention successfully modifies the hypothesised determinants and if these changes mediate behaviour change effects (Baranowski, et al., 1998;Michie & Abraham, 2004).”

• cites Baranowski, et al., 1998Not checked yet

  Not checked in the free run.

• cites Michie & Abraham, 2004Not checked yet

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May combine two claims.

Previous physical activity interventions were weakly effective and maintenance of effects was poor.

“Previous PA interventions were weakly effective (Dishman & Buckworth, 1996;Kahn et al., 2002;Stone, McKenzie, Welk, & Booth, 1998) and maintenance of effects has been poor (Biddle, Gorely & Stensel, 2004).”

• cites Dishman & Buckworth, 1996Not checked yet

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• cites Kahn et al., 2002Not checked yet

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• cites Biddle, Gorely & Stensel, 2004Not checked yet

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May combine two claims.

The intervention programme is based on social cognitive theory, self-regulation theory, and planning, which are treated as evidence-based mediators of physical activity change.

“The intervention is based on social cognitive theory (SCT), self-regulation theory (SRT) and planning as evidence-based mediators of physical activity changes.”

• Also stated in: § DISCUSSION · plain

  “The intervention was based on social cognitive theory and self-regulation theory and incorporates action planning and coping planning.”

Classified as probably not a substantial claim.

Social cognitive theory assumes behaviour is guided by beliefs acquired through interaction with the environment, especially beliefs about consequences and capabilities.

“Social cognitive theory (SCT; Bandura, 1997) assumes that behaviour is guided by beliefs that people acquire in their ongoing interaction with the environment; in particular beliefs about the consequences of behaviour and individual capabilities.”

• cites Bandura, 1997Not checked yet

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Classified as probably not a substantial claim. May combine two claims.

Portuguese adolescents have some of the lowest physical activity levels in Europe and a high prevalence of health risk behaviours.

“Portuguese adolescents show some of the lowest levels of PA in Europe and an overall high prevalence of health risk behaviours (McIntyre et al., 1998;Riddoch, et al., 2004;WHO, 2000).”

• cites McIntyre et al., 1998Not checked yet

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• cites Riddoch, et al., 2004 sourceNot checked yet

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• cites WHO, 2000Not checked yet

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May combine two claims.

Most previous trials were based in the United States and little evidence about behaviour change in European adolescents is available.

“The majority of previous trials have been based in the United States and little evidence about behaviour change in European adolescents is available (Marcus et al., 2006).”

• cites Marcus et al., 2006Not checked yet

  Not checked in the free run.

May combine two claims.

The intervention is of minimal intensity and thus potentially a highly economic means of health promotion in schools.

“The intervention studied is of minimal intensity (two 90 minute sessions on physical activity) and thus potentially a highly economic means of health promotion in schools.”

May combine two claims.

The study used a cluster-randomised design in which two classes per school similar in socio-demographic variables were randomly assigned to intervention or control after initial assessment.

“The study used a cluster-randomised design.In each school two classes similar in socio-demographic variables were selected and randomly assigned to intervention or control condition after initial assessment.”

• Also stated in: § Abstract · plain

  “Two classes, paired on socialeconomic variables, were selected from each of eight Portuguese schools and randomly assigned to an intervention or control group (N=291).”

May combine two claims.

An inexpensive classroom-based intervention can potentially reach a large number of adolescents and produce health promotion effects if a moderate increase in PA is delivered to many individuals.

“An inexpensive classroom-based intervention can potentially reach a large number of adolescents and produce tremendous health promotion effects if a moderate increase in PA can be delivered to a large number of individuals.”

Probably not a substantial claim: may not pass S3 (load-bearing).

A formal mediation analysis was beyond the scope of this paper due to sample size and power considerations.

“Although a formal mediation analysis was beyond the scope of this paper due to sample size and power considerations, pre-post changes in theoretical target variables were analysed to test if the intervention reached its immediate targets (Table 4).”

Classified as probably not a substantial claim.

Random effects were included for school and class to account for potential intra-cluster correlation.

“Random effects were included for school and class to account for potential intra-cluster correlation (Rabe-Hesketh & Skrondal, 2005).”

• cites Rabe-Hesketh & Skrondal, 2005Not checked yet

  Not checked in the free run.

May combine two claims.

Attrition was unrelated to intervention and not biased with regard to social-cognitive or behavioural baseline measures.

“Attrition was unrelated to the intervention and not biased with regard to social-cognitive or behavioural baseline measures.”

May combine two claims.

The findings suggest that the intervention successfully changed the theory-based targets, but a non-significant trend for goal intentions in favour of controls needs further investigation.

“While these findings suggest that the interventions successfully changed the theory-based targets, a non-significant trend for goal intentions in favour of the controls needs further investigation.”

Probably not a substantial claim: may not pass S3 (load-bearing).

In a recent study by Dishman et al. (2004), self-efficacy partly mediated the effects of a comprehensive school-based physical-activity programme in girls of similar age.

“In a recent study by Dishman et al. (2004) self-efficacy partly Theory-based Intervention to enhance Physical Activity Among Adolescents -15mediated the effects of a comprehensive school-based physical-activity programme in girls with a similar age to the students in this study.”

• cites Dishman et al. (2004)Not checked yet

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May combine two claims.

SCT and planning measures were developed based on a belief elicitation study and pilot studies following guidelines of leading theorists.

“SCT measures were developed based on a belief elicitation study and pilot studies (Araújo-Soares, et al., in press;Araújo-Soares, 2006) following the guidelines of leading theorists (Ajzen, 2006;Bandura, 2005).”

• cites Araújo-Soares, et al., in pressNot checked yet

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• cites Araújo-Soares, 2006Not checked yet

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• cites Ajzen, 2006Not checked yet

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Probably not a substantial claim: may not pass S3 (load-bearing).

This could have resulted in a social environment reinforcing physical activity.

“This could have resulted in a social environment reinforcing of physical activity.”

Probably not a substantial claim: may not pass S3 (load-bearing).

There is a growing body of evidence showing linear relationships between physical activity and health.

“However, there is a growing body of evidence showing linear relationships between physical activity and health (Hallal et al, 2006).”

• cites Hallal et al, 2006Not checked yet

  Not checked in the free run.

May combine two claims.

Intervention participants became more aware that their current PA might be insufficient for positive outcomes and developed clearer plans for dealing with barriers to regular PA.

“i.e., they became more aware that their current levels of physical activity might not be sufficient to achieve positive outcomes and developed clearer plans about how to deal with barriers for regular PA.”

May combine two claims.

The intervention seems to facilitate PA with a cumulative effect over nine months, resulting in a difference of nearly one hour per week at trial end.

“The intervention seems to facilitate PA with a cumulative effect over nine months following the intervention resulting in a difference of nearly one hour a week at the end of the trial.”

Classified as probably not a substantial claim.

Data were analysed using three-level random effects ANCOVA linear regression, adjusting post-intervention PA at each time point for pre-intervention PA, age and sex.

“Data were analysed using multilevel modelling techniques; a three level random effects analyses of covariance linear regression, adjusting post-intervention PA at each time point for pre-intervention PA, age and sex.”

Classified as probably not a substantial claim.

The underlying rationale of a theory-based intervention is that behaviour change is achieved by modifying theory-based determinants of behaviour.

“The underlying rational of a theory-based intervention is that behaviour change is achieved by modifying theory-based determinants of behaviour (Michie & Abraham, 2004).”

• cites Michie & Abraham, 2004Not checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The increasing effects may be due to group effects, as the intervention might have changed group norms, creating a culture of mastery and collective self-efficacy.

“This may be due to group effects, as the intervention might have changed group norms, creating a culture of mastery and collective self-efficacy (Bandura, 1997).”

• cites Bandura, 1997Not checked yet

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Classified as probably not a substantial claim.

All analyses were conducted as complete cases intention-to-treat.

“All analyses were therefore conducted as complete cases intention-to-treat analyses (Wood, White & Thompson, 2004;Wood, White, Hillsdon & Carpenter, 2005).”

• cites Wood, White & Thompson, 2004Not checked yet

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• cites Wood, White, Hillsdon & Carpenter, 2005Not checked yet

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• AssumptionThe authors state this as an assumption: Missing data were missing completely at random.

Probably not a substantial claim: may not pass S3 (load-bearing).

Previous research has shown that adolescents often lead sedentary lifestyles despite good intentions to be active.

“Previous research had shown that adolescents often lead sedentary lifestyles despite good intentions to be active (Araújo-Soares, McIntyre & Sniehotta, in press;McIntyre et al., 1998;Riddoch et al., 2004).”

• cites Araújo-Soares, McIntyre & Sniehotta, in pressNot checked yet

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• cites McIntyre et al., 1998Not checked yet

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• cites Riddoch et al., 2004 sourceNot checked yet

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Probably not a substantial claim: may not pass S3 (load-bearing).

A conservative sensitivity analysis imputing baseline PA for missing data was carried out to test robustness.

“To test the robustness of the results to this assumption we also carried out a conservative sensitivity analysis imputing the baseline levels of PA for any missing data.”

Classified as probably not a substantial claim.

Most behavioural interventions show immediate effects that over time lack sustainability.

“Most behavioural interventions show immediate effects that over time lack sustainability (Marcus et al., 2006;Biddle et al., 2004).”

• cites Marcus et al., 2006Not checked yet

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• cites Biddle et al., 2004Not checked yet

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May combine two claims.

Feasibility and acceptability of the intervention and training procedures were established in a one-group design with pre, post and 9-month follow-up in 107 students from four schools.

“Feasibility and acceptability of the intervention and the training procedures were established in a one-group design with pre, post and 9 months follow up, with 107 students from four different schools in Northern Portugal.”

Probably not a substantial claim: may not pass S3 (load-bearing).

These findings are in line with recent evidence that theory-based measures of cognitions mediate the effects of theory-based interventions.

“These findings are also in line with recent evidence that theory-based measures of cognitions mediate the effects of theory-based interventions.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Seasonal effects might have contributed to the observed differences.

“Moreover, seasonal effects might have contributed.Baseline measures were taken in October/November (autumn), post-tests in November/December (winter), 3-months follow-up in March (spring and period for school exams) and the 9-months follow-up took place in September (end of summer vacations).”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

SCT is an evidence-based theory of individual-environment interaction, holding that the environment influences behaviour by shaping and constraining beliefs.

“SCT is an evidence-based theory about the interaction of individual and environmental factors and argues that the environment affects behaviour by constraining and changing beliefs (Bandura, 1997).”

• cites Bandura, 1997Not checked yet

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Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

That smoking cessation study found no benefit of planning because few participants were smokers.

“This study failed to find beneficial effects of planning because few subjects turned out to be smokers.”

• cites Higgins & Conner, 2004Not checked yet

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May combine two claims.

The IPAQ is one of the most studied self-report measures, and validation studies show good reliability and acceptable validity against accelerometer measures.

“The IPAQ is amongst the best-studied self-report measures and validation studies indicate good reliability and acceptable validity with regard to accelerometer measures (Craig et al., 2003).”

• cites Craig et al., 2003Not checked yet

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Probably not a substantial claim: may not pass S3 (load-bearing).

Using matched control and intervention classes within the same schools could have biased the findings through interaction between adolescents in both classes.

“Comparing matched control classes with intervention classes in the same schools might have biased the findings due to interaction between adolescents for both classes.”