Table 2 Summary of key results and conclusions for the effectiveness of the app techniques

Feedback

 Qual.

 Quant.

18 vs. 0

12 vs. 2

Presence of feedback was the app technique most often studied; in all but one study, it was supported to foster PA. Hence, feedback is an effective and robust app technique in promoting PA

Goal setting^a

 High

  Qual.

  Quant.

4 vs. 1

1 vs. 1

Presence of high goals was fairly often studied and supported to foster PA in all but two studies. Hence, based on these results, goal setting with challenging goals seems for the most part an effective app technique in promoting PA

 Low

  Qual.

  Quant.

4 vs. 0

4 vs. 0

Presence of low goals was often studied and supported to foster PA in all studies. Hence, based on these results, goal setting with less challenging goals is an effective app technique in promoting PA, which is probably more effective than challenging goals

 Reward

  Qual.

  Quant.

3 vs. 2

1 vs. 1

Presence of reward was fairly often studied, and results were mixed. Based on this, we cannot yet draw definite conclusions about its effectiveness in fostering PA. Additional research that explains the mixed findings is needed

Social sharing

 Familiar users in segregated groups

  Qual.

  Quant.

4 vs. 0

1 vs. 0

Presence of social sharing with familiar users in segregated groups was occasionally studied and, in all studies, supported in fostering PA. Hence, this social sharing type appears promising as an effective app technique for promoting PA

 Familiar users in social networks

  Qual.

  Quant.

2 vs. 1

1 vs. 0

Presence of social sharing with familiar users in social networks was one of the least studied techniques, and in three studies versus one, was shown to foster PA. Thus, pending future research, this social-sharing type might also be an effective app technique for promoting PA

 Strangers in segregated groups

  Qual.

  Quant.

1 vs. 3

2 vs. 2

Presence of social sharing with strangers in segregated groups was often studied. In three studies, it was supported as fostering PA; in five, not. Hence, results indicate that this sharing type seems rather ineffective but may work under special conditions that need to be identified in additional research

 Strangers in social network

  Qual.

  Quant.

0 vs. 2

–

Presence of social sharing with strangers in social networks was one of the least often studied app techniques, and in two studies, it was not found to be a driver of PA, with particularly strong negative reactions of users. Hence, this social sharing type is, pending research, probably not effective in promoting PA

Competition

  Qual.

  Quant.

7 vs. 1

3 vs. 1

Presence of competition was often studied, and all but two studies supported it as a driver of PA. Hence, results render competition for the most part an effective app technique in promoting PA