The carbohydrate periodisation framework is a widely accepted nutritional intervention strategy in the field of sports nutrition. However, despite the validity of this approach, it is reported that athletes find it difficult to stick to this behaviour and that the support required is highly personalised, and as a result time consuming for the coach. Prior research has suggested that a digital environment can deliver better personalised dietary interventions to better support athletes.

The overall purpose of this study is to assess the feasibility and acceptability of a digital approach (a menu planner app with coach support), and gain understanding on the strategy to implement coach support according to app engagement in the digital approach to improve dietary carbohydrate periodisation behaviours in athletes.

The study is conducted in two consecutive parts.

For part one, to assess the feasibility and acceptability of the digital approach, participants are recruited to use the app for 6 weeks and were given coach support, where coaches message (MesC) and call (ad-hoc Call) and the participants. A control group (no app) is also separately recruited to compare with the menu planner group.

For part two, to gain better understanding on the strategy to implement coach support with the menu planner app according to app engagement, a pilot multiple assignment randomized trial (SMART) design is conducted. Participants are equally randomised to either receive a stringent engagement criteria strategy or relaxed adherence criteria strategy. A stringent engagement criteria strategy requires the user to use the app at least twice a week at stage 1, and at least 3 times a week at stage 2 to be considered a responder at stage 1 and stage 2 (R1 and R2).

A relaxed engagement criteria strategy requires the user to use the app at least once a week in week 1 of using the app at stage 1, and at least 2 times a week at stage 2, to be considered a responder at stage 1 and stage 2 (R1 and R2). Non-responders for both criteria strategies at stage 1 and 2 (NR1 and NR2) will be re-randomised to either continue with the app only or additional coach support (MesC + ad-hoc Call).

Timeline wise,

Stage 1: Participants will first receive app for 1 week and will be categorised as responder (R1) or non-responders (NR1) at the end of the 1 week.

Stage 2: Responders to stage 1 (R1) will continue with the menu planner for 1 week. Non-responders to stage 1 (NR1) will either continue with the menu planner or receive additional coach support (MesC + ad-hoc Call) for 1 week. Participants are categorised again as responder (R2) or non-responders (NR2) at the end of the week.

Stage 3: Responders to stage 2 (R2) will only have menu planner for 2 weeks. Non-responders to stage 2 (NR2) will either have menu planner only or receive/continue with additional coach support (MesC + ad-hoc Call) for 2 weeks.

The SMART trial will take a total of 4 weeks to complete and have up to two randomisation points per participant. All re-randomisations are done at 1:1 allocation ratio.

Inclusion Criteria:

• Have access to a personal smart phone.
• An elite or training athlete.
• Have a performance related weight loss or weight maintenance physical goal.
• Do not have or have not have a history of eating disorders or disordered eating.

Exclusion Criteria:

• Participants with a medically diagnosed history of eating disorders or disordered eating will be asked to self-exclude from the study.

The deidentified individual participant data may be shared with other researchers on a case by case basis upon request and subject to Data Protection Officer approval.