Table 1 Suggested actions for improving the level evidence for physical activity interventions in young people (structured by intervention mapping (IM) steps)

Needs assessment

Ensure timely input from your stakeholders at key points in the research process. Public Involvement, qualitative research and process evaluations will help inform and adapt interventions and evaluations to make them acceptable and relevant to the target audience and feasible for implementation, but only if you take into account the information it produces.

Listen to others and their opinions

Matrices

Carefully consider your target population and the potential negative and positive consequences of targeting. Consider comparing the feasibility, acceptability, and effectiveness of targeted vs. non-targeted interventions in a trial.

The whole forest of just a tree?

Theory

Use relevant theory, and feedback from your target audience, to understand how we might be able to achieve sustained engagement through, for example, focusing on autonomous forms of motivation.

Fun, fun, fun

Program

Carefully design your intervention and link it to a pre-defined causal model. This helps guide your evaluation and improve our understanding of causation.

To map or not to map?

Implementation

Plan ahead for the inclusion of a detailed (mixed-methods) process evaluation to allow for a deeper understanding of the (lack of) intervention effect.

The intervention delivery intention-behaviour gap

Evaluation

Implement recruitment and retention strategies based on the best available evidence, and report on them and their effectiveness to inform future research.

To recruit and to retain

Consider how to schedule measurements to avoid bias due to for example weather or influences of ‘special days’.

Timing is everything

Include upstream outcomes, preferably objectively-measured – this is likely to increase impact at the policy and practice level.

Keep it real

Don’t miss the often “neglected” assessment at long-term follow-up - make early provisions.

Happily ever after…?

Include evidence for policy makers that the intervention is worth it. This may involve collaboration with health economists to evaluate the cost-effectiveness of your intervention.

Money makes the world go round

Design your evaluation to enable studying mediators and moderators. Use your pre-defined causal model and consider the timing of assessment and statistical power.

Look under the bonnet

Dissemination

Report everything, preferably in a single paper, and tell it as it is to increase our collective understanding of the complexity of intervention effects.

The whole truth, and nothing but the truth