The impact of dietary fibre and a carbohydrate-fibre-FODMAP gel on gut health and symptoms during exercise.

Intervention Description (All Trials) Physical/Informational Materials: Participants will receive written meal plans and food lists tailored to the dietary condition (high fibre, low fibre, carbohydrate supplementation). The kiwiberry gel is provided in pre-measured sachets. A brief guide on how to consume the gel during exercise will also be included. All materials are developed by Accredited Practising Dietitians (APDs). Procedures and Activities: Participants will complete the following protocol for each trial: •Pre-trial diet: 2 days of prescribed dietary intake (either high or low fibre) inclusive of breakfast, lunch, dinner, and snacks. •Pre-exercise meal: Low fibre (Approximately <1g fibre) breakfast 2 hours before trial. •Exercise: 2-hour treadmill run at 60% maximal effort in a controlled 35°C lab environment. 1h recovery period prior to completing a 20-minute performance/distance test. •A trained researcher will perform a 30-minute electrogastrography (EGG) recording both before exercise and again following the 2-hour exercise period. This procedure is used to measure the electrical activity of your stomach. You will be asked to lie down in a supine (face-up) position and remain completely still for the duration of the recording. To ensure accurate results, you will need to remove all metal jewellery and avoid contact with any metal during the procedure. To prepare for electrode placement, three small areas on your abdominal skin will be cleaned and gently abraded with gauze. If necessary, any hair in these areas will be shaved to improve signal quality. A small amount of gel will be applied to each site, and three disposable surface electrodes will then be attached. Electrode leads will be connected to these sensors to capture the readings. This non-invasive procedure will be performed by researchers trained and experienced in EGG data collection. •Performance test: 20-minute treadmill distance test, 1h after the 2h exercise period. Intervention / Exposure Description Trial: High Fibre •Diet: High fibre intake (Approximately 52 g/day) for 2 days prior to trial (prescribed meals). •Pre-exercise meal: Low fibre (Approximately <1g fibre) breakfast 2.5 hours before trial. •Exercise intake: Water only during the 2-hour exertional heat stress protocol. •Performance test: 20-minute treadmill distance test, 1h after the 2h exercise period. Trial: Low fibre, Carbohydrate Supplement During Exercise •Diet: Low fibre intake (Approximately 10 g/day) for 2 days prior to trial (prescribed meals). •Pre-exercise meal: Low fibre (Approximately <1g fibre) breakfast 2.5 hours before trial. •Exercise intake: Kiwiberry gel (containing 30g carbohydrate per gel, FODMAPs and fibre), consumed starting at 15 minutes and then every 15 minutes thereafter until 90 minutes of the 2-hour exertional heat stress period. No gel will be consumed in the final 30 minutes of the exercise session. •Performance test: 20-minute treadmill distance test, 1h after the 2h exercise period. Mode and Setting of Delivery: In-person at a controlled laboratory setting in a university-based heat chamber and human performance lab. Individual delivery. BASE Facility, Monash University, Exercise Physiology Laboratory, by co-investigator, research students and Chief Investigator. Frequency, Schedule, Duration: To complete all aspects of the study, each participant will complete the following: •One occasion for the initial assessment (approx. 1-1.5 hour). •3 occasions for the exercise trials (approx. 7 hours each). – each separated by approximately 6-10 days. •One occasion to provide a faecal sample (approx. 15 mins). •10 – 15 mins to complete food and exercise diary reporting intake for the 48 hours prior to experimental trial. •Approximately 60 minutes in total to complete two 2-day estimated food intake diaries of your habitual diet (i.e. one at the start and one later in the study). Total time required: 24.5 hours Location: BASE Facility, Monash University, Level 1, 264 Ferntree Gully Road, Notting Hill. Exercise Physiology Laboratory. Personalisation/Adaptation: The intervention is not personalised or titrated. All participants follow standardised dietary and exercise protocols for consistency and comparability between trials. Adherence and Fidelity: Adherence will be assessed through: •Pre-trial diet logs reviewed by APDs. •Supplement consumption monitored and recorded during the trial. •Exercise and test protocol adherence supervised in-lab. Fidelity strategies include: •Training sessions for staff conducting assessments. •Use of standardised instructions and checklists. •Supervised administration of all trial components.