Investigating the circulating sphingolipidome response to a single high-intensity interval training session within healthy females and males in their twenties: the SphingoHIIT randomised controlled trial.

Growing scientific evidence shows that specific sphingolipids, known as ceramides, predict cardiovascular risk beyond traditionally used biomarkers such as lipoproteins and triglycerides. Mechanistically, ceramides have been shown to promote foam cell formation, vascular inflammation, peripheral insulin resistance, and ultimately atherosclerosis. Currently, however, it remains unclear if and how physical activity, a simple, low-cost, and patient-empowering mean to optimise cardiometabolic health, can mitigate sphingolipid levels. The SphingoHIIT study aims to assess how certain circulating sphingolipid species respond to a single session of high-intensity interval training (HIIT). We hypothesise that circulating sphingolipid levels will be temporarily increased following a single HIIT session. This risk category A study will last 11 days and include 32 healthy participants aged between 20 and 29 years (50% of females). Participants will be randomly allocated either to the intervention group (n= 16) or the control group (n= 16). Blocked randomisation will be used to reduce bias and achieve balance in the allocation of participants to both groups, as commonly done when the sample size is small. Following an assessment of inclusion and exclusion criteria, a maximal cardiopulmonary exercise testing will be performed to determine peak oxygen uptake and peak heart rate. A washout period of five days will then be carried out before participants start to self-sample fasted dried blood spots to determine baseline levels of sphingolipids. After three days of sampling, participants will undergo a single HIIT session. Dried blood spots will be collected at five additional fixed time points (2min, 15min, 30min, 60min, and 24h) following the HIIT session. To minimise the dietary influence, participants will be asked to solely consume the provided individualised, pre-packaged meals starting one day before the first dried blood sampling.

Additionally, for the duration of the whole study, participants will wear a wrist accelerometer to track their physical activity. The SphingoHIIT study is expected to provide novel knowledge regarding the effect of an acute bout of physical exercise on sphingolipid levels. The results of this study will be published in a peer-reviewed journal and will be presented at scientific conferences.