Endurance Trial: Ketone and Carbohydrate Supplementation

Description

This randomized, double-blind, crossover study investigates the effects of exogenous ketone supplementation on physical and cognitive performance in amateur endurance athletes during exhaustive exercise. Participants will complete three 3-hour cycling sessions under different nutritional conditions: carbohydrate alone (CHO), carbohydrate plus ketone (CHO-KET), and placebo (PLA). The study will assess cognitive function through validated computerized tests, physical performance via distance covered, and metabolic responses through blood biomarkers. Additionally, peripheral blood mononuclear cells (PBMCs) will be collected and cultured with LPS or not. Other PBMCs co-cultured with neuronal cells (SH-SY5Y) to investigate neuro-immune interactions. The primary hypothesis is that ketone supplementation will preserve cognitive function and enhance physical performance during prolonged exhaustive exercise compared to carbohydrate supplementation alone, potentially through anti-inflammatory mechanisms and alternative energy substrate provision.

Interventions

• Carbohydrate beverage (Dietary supplement)
  Participants ingest 210 mL of a \~15% carbohydrate solution, providing 30 g of carbohydrate per dose, every 20 minutes from the start of the 155-minute fixed-intensity phase, with the final dose taken immediately before the start of the 20-minute maximal effort block. No beverage is provided during the maximal effort. The solution combines sucrose and dextrose so that glucose and fructose are absorbed through separate intestinal transporters. All doses are supplied in opaque, coded bottles prepared by a researcher not involved in the assessments, so that treatments cannot be identified visually.
• (R)-1,3-butanediol (Dietary supplement)
  Participants ingest (R)-1,3-butanediol at 1.0 g/kg body mass 45 minutes before the start of the cycling protocol and a further 0.5 g/kg 5 minutes before the start, for a total dose of 1.5 g/kg body mass. The dose was selected to sustain blood beta-hydroxybutyrate at approximately 2 mmol/L throughout the session, a range compatible with nutritional ketosis and without risk to participants. Doses are supplied in opaque, coded bottles prepared by a researcher not involved in the assessments.
• Pre-exercise non-caloric placebo (Dietary supplement)
  Participants ingest a non-caloric placebo beverage at 45 and 5 minutes before the start of the cycling protocol, at the same time points at which the (R)-1,3-butanediol is administered in the CHO-KET arm. The placebo is matched to the ketone beverage for volume, appearance and flavour, and provides no energy. Doses are supplied in opaque, coded bottles prepared by a researcher not involved in the assessments.
• During-exercise non-caloric placebo (Dietary supplement)
  Participants ingest 210 mL of a non-caloric placebo beverage every 20 minutes from the start of the 155-minute fixed-intensity phase, with the final dose taken immediately before the start of the 20-minute maximal effort block. No beverage is provided during the maximal effort. The placebo is water with the same flavouring used in the carbohydrate beverage, matched for volume, appearance and ingestion schedule, and provides no energy. Doses are supplied in opaque, coded bottles prepared by a researcher not involved in the assessments.
• Standardized evening meal (Other)
  On the evening before each experimental session, participants consume a standardized meal providing 1.5 g of carbohydrate per kg of body mass. The same meal is provided before all three experimental sessions and is followed by an overnight fast of 8 to 12 hours.
• Prolonged cycling exercise protocol (Other)
  Each experimental session comprises 5 minutes of warm-up at 100 W, 155 minutes at 55% of maximal power output (Wmax) with the cycle ergometer set in hyperbolic mode, and a final 20 minutes of maximal self-paced effort in linear mode, followed by 5 minutes of low-load cool-down. The same protocol is applied in all three conditions, with load individually prescribed from the maximal incremental test performed at the pre-experimental visit.
• Standardized breakfast (Other)
  On the morning of each experimental session, after the baseline venous blood draw and following an overnight fast of 8 to 12 hours, participants consume a standardized breakfast providing 1.5 g of carbohydrate per kg of body mass, 40 g of protein and 7 g of fat. Participants are instructed to consume the entire meal. The same breakfast is provided before all three experimental sessions.

Eligibility criteria

Conditions

Locations

• School of Physical Education and Sport of Ribeirão Preto - University of São Paulo — Ribeirão Preto, São Paulo, Brazil