Digital Mindset Intervention for Half Marathon Performance

The primary study outcome is the official half-marathon finish time recorded for each participant (in hours, minutes, and seconds)

Number of participants who complete a half marathon, across each study arm.

Number of days it took participants to feel fully recovered from their half-marathon race. For example, when fatigue and muscle pain subsided.

The number of days each participant ran during their peak training week before the half-marathon race.

Measured with the question:

During your peak training week, how many days did you train? (days/week)

The total distance (in kilometers) that each participant ran across all training runs during their peak training week prior to the half-marathon race.

Measured with the question:

During your peak training week, what was the total distance you ran across all your runs that week? (km)

The Body Mindset Inventory - Version 2 (BMI-2), adapted for half-marathon runners.

Assessed using 6-point Likert scale (1 = Strongly disagree, 6 = Strongly agree).

Perceived influence of mindset vs. training schedule on race performance

Assessed via two self-report items using 10-point Likert scales (1 = Not at all, 10 = An extreme amount):

"How much do you think your mindset influenced your half marathon training and performance?"

"How much do you think your training schedule influenced your half marathon performance?"

A difference score will be calculated by subtracting the response to item 2 (training schedule) from item 1 (mindset). This score reflects the participant's relative attribution of their performance to mindset vs. training. Positive scores indicate greater perceived influence of mindset; negative scores indicate greater influence of the training schedule.

The extent to which participants interpret common sensations during challenging runs (e.g., fatigue, muscle discomfort, heavy breathing) as indicators that their body is getting stronger. Responses are collected using a 10-point visual analogue scale ranging from 1 ("not at all signs of getting stronger") to 10 ("definitely signs of getting stronger").

Participants' belief in their ability to influence their mindset, even in high-stakes situations, measured using one item from the Controllable Meta-Mindset Scale: "Even in moments when it really matters, I can't do much to change my mindset." Responses are rated on a 6-point Likert scale (1 = Strongly disagree, 6 = Strongly agree).

Participants' beliefs about the role of expectations in their upcoming half-marathon performance. Measured using a single item:

"To what extent do you think your expectations will affect your half-marathon performance?", using a 6-point Likert scale (1 = Not at all, 6 = An extreme amount)

How likely study participants are to participate in another half marathon or endurance race. Measured with 5-point Likert scale (1 = Not at all likely, 5 = Extremely likely).

How satisfied people are with their race day performance. Measured with 5-point Likert scale (1 = Not at all satisfied, 5 = Very satisfied).

Change in half-marathon race time, calculated as the difference (in minutes:seconds) between each participant's self-reported previous personal best and their official finish time in their 2025 half-marathon (for those with a prior half-marathon result).

Did participants perform better or worse than their goal time for the half marathon. Measured via a single-item question administered post-race: "Was this time better or worse than your goal time?" Participants select one of four response options: Better; About the same; Worse; I did not have a goal time

Whether participants experienced any running-related injuries, measured with a single yes/no response question. Since enrolling in this study, did you experience any running-related injuries - before, during, or after your half-marathon race? (Yes (please specify) / No)

Participants' self-reported adherence to their intended training plan in the weeks leading up to the race. Assessed via a single-item question using a 5-point Likert scale:

"How often did you follow your planned training sessions in the weeks leading up to the race?" (1 = Rarely followed my plan, 5 = Followed my plan consistently)

Participants are invited to provide an optional open-text response to the prompt: "What thoughts come to mind when you think about your upcoming half marathon right now?" This will be used to explore participants' anticipatory beliefs and expectations before training and intervention delivery.

Participants are invited to complete two optional follow-up prompts:

• an open-text reflection on how their training and participation in the Mount Maunganui Half Marathon 2025 went, and
• a brief prompt asking them to provide two words that best describe their overall experience.

These responses will be used to qualitatively explore participant perceptions of their training journey and race experience.

Acceptability of the intervention content. Measured with four summed items on a 5-point Likert scale (Scale: 1 = Strongly disagree, 5 = Strongly agree).

The digital content was clear and easy to understand. The digital content helped me perform better during my half marathon. The digital content motivated me to stay consistent with my training. The digital content helped me reframe discomfort during training and my half marathon in a helpful way.

Participants' prior experience with half-marathon events. Measured using a single self-report item: "How would you describe your half-marathon experience level?" Participants select from two predefined options: (1) Beginner (training for your first half marathon) (2) Intermediate (previously completed up to 2 half marathons).

Self-reported fastest half-marathon finish time to date. Participants enter their best recorded time in hours and minutes.

How often participants currently run each week. Measured with a single self-report item: "How many days per week do you currently run for exercise?" Options: None; 1 day; 2-3 days; 4-5 days; 6-7 days.

Participants' typical running distance per session. Measured using a self-report item: "What is the average distance of your current runs (in kilometers)?"

Whether participants are following a structured training plan for their upcoming race. Measured with a Yes/No self-report question: "Do you have a training plan for your Half Marathon?"

Participants' target finish time for the upcoming half marathon. Measured via a self-report item: "Do you have a goal time for the half marathon?" If yes, participants specify their goal time in hours and minutes.

How long participants typically take to recover from a long training run. Measured with a single self-report item: "How many days do you typically take to recover from a long run?" Options: 1 day; 2 days; 3 or more days; N/A (I haven't started running yet).