Feasibility, Acceptability and the Effects of Two Publicly Available Physical Activity Mobile Apps

Within the new digital health care landscape, the rise of health applications (apps) creates novel prospects for behaviour change opportunities. The commercial market is saturated with apps that aim to increase physical activity (PA) with more than 49,000 PA apps available in the major app stores in 2016 \[1\]. Despite the wide distribution and popularity of PA apps, research on the efficacy of the apps is lacking.

This project focuses on exploring the potential for increasing PA levels using 2 selected apps that are available on the market with participants that do not engage or perform very little PA. This study is timely because PA apps on the market are extremely popular and there is a clear need to this the potential of these potentially convenient, accessible, wide-reaching, and cost-effective technology.

Before a large scale study is conducted, it is crucial to conduct assessment of the feasibility and acceptability of the study \[2\]. Feasibility determines if the study design, procedures, and the intervention can be executed by the researcher. Acceptability assesses the suitability of the study design, procedures, and the intervention from the perspective of the participants and intervention deliverers \[3\]. Hence, this mixed-methods feasibility study was designed to inform a decision about whether to proceed to a large-scale study. The aim of this study is to investigate the feasibility and acceptability of a study assessing 2 selected PA apps to inform the design of a definitive RCT, and to assess the effects of the app interventions on PA

The aim of this research project is to investigate the feasibility and acceptability of a study assessing 2 selected PA apps to inform the design of a definitive randomised controlled trial, and to assess the effects of the app interventions on PA.

To address the aim, an explanatory mixed-methods study using quantitative (phase 1) and qualitative (phase 2) design will be used. Target population will be those that do not engage, or engage in low levels, of PA and the investigators will aim at recruiting participants from London and surrounding areas.

The primary objective is to determine the feasibility and acceptability of the trial procedures and the interventions delivered using apps.

The secondary objectives are to explore potential effects of the 2 selected PA apps on behavioural and psychological outcomes, and to assess the usability of the apps.

Phase 1 Phase 1 will utilise a crossover which means that half of the participants will be randomly assigned to use 1 of the 2 apps, while the other half will use the 2nd app. After 2 weeks participants will switch.

Participants will complete a baseline assessment (1 week), followed by the randomisation to using 1 of the 2 apps (2 weeks' follow up), and crossover (4 weeks' follow up). The primary outcome of the study will be average percent increase in activity count and will be measured using accelerometer. The secondary measures include exercise self-efficacy, intentions, apps usability and usage.

Phase 2 Following the end of phase 1, a semi-structured interview will be conducted to explore the acceptability and experiences of using the 2 apps (phase 2). The sample will include participants that took part in the crossover trial and consented to being interviewed. Participants that showed frequent usage of the apps, as well as those who used the app infrequently and/or discontinued using the app will be interviewed.

Eligibility Criteria:
Inclusion Criteria:

* adults (≥18 years' old) identified as "moderately inactive" or "inactive" using General Practice Physical Activity Questionnaire
* as the use of accelerometer requires some maintenance from the researcher, it was necessary to include only users that reside in/around London for practical reasons
* willingness to try the apps assessed in the study (walking and workout app)
* those owning a smartphone, iPhone (operating iOS 6.0 or newer and ) or Android (version 2.3.3 and up

Exclusion Criteria:

* do not speak English
* previous use of the apps of interest
* medical conditions that require special attention when conducting physical activity
* current participation in another research study that targets behaviour change