Abstract
BackgroundThere is some evidence that simply measuring physical activity alone can increase self-reported physical activity behaviour. Objective measures of physical activity in intervention studies have increased substantially over the last decade. Yet, there is no synthesised evidence of observed changes in the control group physical activity in trials that have used objective physical activity measurement approaches. Understanding factors associated with control group increases (or decreases) in physical activity may have implications for planning physical activity research and in clinical settings where objective measures of physical activity may be used. The aim of this systematic review is to describe changes in objectively measured physical activity that have occurred within control groups in primary care physical activity intervention studies and, if possible, identify factors that are potentially associated with these changes.MethodsThe PRISMA-P reporting guidelines for systematic review protocols will be followed. Five electronic databases (PubMed, MEDLINE, SPORTDiscuss, PsychINFO, CINAHL) will be searched to identify physical activity controlled (randomised, cluster, quasi-experimental) studies conducted with adults in primary care. Search terms will be based on previous systematic reviews, and only peer-reviewed articles published in English will be considered. The main outcome measure is the change in objectively measured physical activity within the control group. Risk of bias will be assessed using the Cochrane Collaboration tool and the Risk Of Bias in Non-randomised Studies—of Interventions tool. Meta-analyses will be conducted where possible among studies with sufficient homogeneity.DiscussionThis systematic review and meta-analysis will determine the extent to which physical activity measurement alone is associated with changes in objectively measured physical activity levels in control groups in primary care. Findings from this study will inform future physical activity intervention research and practice. If measuring physical activity alone is associated with increases in physical activity levels that may be considered beneficial for health, this could indicate that measurement alone may be a low cost, efficient and effective method to increase a proprotion of the population’s physical activity levels.Systematic review registrationPROSPERO CRD42018104896
Highlights
There is some evidence that measuring physical activity alone can increase self-reported physical activity behaviour
The mere-measurement effect, or the question-behaviour effect, refers to the change in behaviour under investigation following measurement of the behaviour and/or related cognitions [5]. These mechanisms are recognised as potential challenges when calculating sample sizes and interpreting results of controlled physical activity intervention studies due to the likely small increase in physical activity levels in the control group, making it difficult to interpret measurement and intervention effects [4, 5]
The authors concluded that the increased frequency of physical activity measurements affected the participants’ self-reported physical activity behaviour. These findings suggest that completing questionnaires about physical activity may not affect objectively assessed physical activity, with more evidence for measurement affecting self-reports of behaviour than objectively measured behaviour [4], there have been some reports of measurement reactivity using accelerometers [9, 10] and pedometers [11]
Summary
Design To facilitate the design and reporting of this protocol for a systematic review and meta-analysis, the Preferred Reporting Items for Systematic Reviews and MetaAnalyses Protocol (PRISMA-P) statement will be followed [18]. Mean changes in the control group objectively measured physical activity will be recorded and if, not reported, calculated by subtracting the mean value at baseline from the mean value immediately post-intervention and follow-up [6]. Forest plots will be created using RevMan 5.3 [26] to synthesise the measures of effect and 95% confidence intervals for the control group changes in objectively measured physical activity, evidence from dissimilar study designs and outcome types will not be reported in the same forest plot. Analysis of subgroups will be performed if sufficient data is available These subgroup analyses may be conducted on the basis of differences between health status, control group intervention, mode of administration, duration between assessments, number of interim assessments, time between interim assessments and intensity of physical activity measurements
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