A single HIIT session does not alter blood sphingolipid levels in healthy young adults: The SphingoHIIT randomized controlled trial.

Introduction: Sphingolipids and ceramides have been identified as critical drivers of cardiometabolic diseases. Ceramide-based scores were developed, predicting cardiometabolic risk independently of and beyond low-density lipoprotein cholesterol. To date, it remains largely unknown whether exercise can modulate sphingolipid levels. Methods: The SphingoHIIT study was the first parallel randomized controlled trial to investigate the impact of a single session of high-intensity interval training (HIIT; 4 ×4 min at 85-95 % of maximal heart rate) on blood sphingolipid levels. Thirty-six healthy young individuals (aged 20-29 years; 50 % female) were randomly assigned to a HIIT (n = 18) or control group (physical rest, n = 18). Sphingolipid levels were measured from dried blood spots collected over three days before and at five time points after the intervention (2, 15, 30, 60 min, and 24 h). Study conditions were tightly controlled: females were tested during the early follicular phase of their menstrual cycle, and standardized meals were provided for four consecutive days before blood sampling. Results: Forty-seven sphingolipid species were acquired, including 25 ceramides, eight glycosphingolipids, eight sphingomyelins, and six sphingoid bases. After adjusting for sex, body fat mass, cardiorespiratory fitness, and daily physical activity, linear mixed models showed no significant differences in sphingolipid levels between the HIIT and control groups at any post-intervention time point. Conclusion: The present findings suggest that circulating sphingolipids are resilient to an acute bout of intensive exercise, an interesting feature for potential biomarkers of cardiometabolic risk. Future studies should investigate whether regular exercise influences sphingolipid levels and improves cardiometabolic health in different clinical populations.