The Impact of Obesity on C1q/TNF-Related Protein-9 Expression and Endothelial Function following Acute High-Intensity Interval Exercise vs. Continuous Moderate-Intensity Exercise

SIMPLE SUMMARY: Lifestyle modifications such as diet and exercise are a first-line defense to promote health in individuals with obesity. High-intensity interval exercise has recently gained popularity as a time-effective exercise modality. As such, this work compared the acute exercise induced benefits on vascular health between high-intensity interval exercise and traditional continuous moderate-intensity exercise. We found that both exercise modalities lead to improvements in indicators of vascular health, with some enhancements lasting up to 2 h following exercise. Therefore, high-intensity interval exercise is a time-effective strategy to improve vascular health similarly to traditional continuous moderate-intensity exercise in individuals with obesity. ABSTRACT: C1q-TNF-related protein-9 (CTRP9) increases endothelial nitric oxide synthase and reduces vasoconstrictors. There is limited information regarding exercise-mediated CTRP9 in obesity. The purpose of this study was to compare high-intensity interval exercise (HIIE) and continuous moderate-intensity exercise (CME) on the CTRP9 response and an indicator of endothelial function (FMD) in obese participants. Sixteen young male participants (9 obese and 7 normal-weight) participated in a counterbalanced and caloric equated experiment: HIIE (30 min, 4 intervals of 4 min at 80–90% of VO(2) max with 3 min rest between intervals) and CME (38 min at 50–60% VO(2) max). Serum CTRP9 and FMD were measured prior to, immediately following exercise, and 1 h and 2 h into recovery. CTRP9 was significantly increased immediately following acute HIIE and CME in both groups (p = 0.003). There was a greater CME-induced FMD response at 2 h into recovery in obese participants (p = 0.009). A positive correlation between CTRP9 and FMD percent change was observed in response to acute CME when combined with both obese and normal-weight participants (r = 0.589, p = 0.016). The novel results from this study provide a foundation for additional examination of the mechanisms of exercise-mediated CTRP9 on endothelial function in individuals with obesity.