Effects of Exogenous Ketones on Acute Changes and Recovery of the Heart Muscle After Intense Exercise.

It is well known that scar tissue on the heart muscle can cause (life-threatening) arrhythmias. However, the exact cause of this scar tissue is not entirely clear. It is possible that prolonged and intense exercise is associated with (limited) inflammation of the heart muscle, carrying the risk of scar tissue development. The aim of this project is to evaluate the impact of prolonged and intense exercise on the heart. Participants will be asked to cycle for a total of 3 hours, of which 2 hours will be at an intense pace. Approximately 30 recreational cyclists will be invited to participate in this research project. Specifically, the investigators want to examine whether prolonged and intense exercise is associated with inflammation of the heart muscle and whether it affects heart function recovery. The research project will take place in a laboratory setting, where heart rate, blood pressure, food and fluid intake, and exertion level will be monitored. Before, after and 20-24h after the intense exercise, a lab test and extensive heart imaging will be performed using magnetic resonance imaging (MRI) and cardiac ultrasound. The investigators aim to study the effect of ketone intake (a dietary supplement that may enhance performance or recovery) on recovery. For this, a double blind cross-over design will be setup. Participants will complete the same exercise twice, with a 1-3 week interval, once with a placebo and once with ketones. All the same baseline, post-exercise and recovery investigations will be perfromed. In the second part of the study, the investigators will evaluate and compare various rhythm-monitoring devices, both during intense exercise and in daily life. For this, participants will be asked to wear each of four devices for one week in a home setting. These are very small devices that are not externally visible when worn under clothing. Participation in this project will involve a various questionnaires and tests.