Acute high-intensity interval exercise induces comparable levels of circulating cell-free DNA and Interleukin-6 in obese and normal-weight individuals.

Aims: Obesity is associated with lipid aggregation in adipocytes and macrophage infiltration, leading to increased oxidative stress and inflammation. Increased cell-free DNA (cfDNA) concentrations have been observed in clinical conditions of systemic inflammation. While the beneficial effects of regular physical activity on the release of circulating cfDNA still remain unknown, acute intense exercise has been shown to increase inflammatory cytokines and cfDNA concentrations in normal-weight individuals. Therefore, the primary purpose of this study was to examine the effect of acute high-intensity interval Exercise (HIIE) on plasma cfDNA and interleukin-6 (IL-6) responses in obese and normal-weight subjects.

Main Methods: Fourteen male subjects (7 obese and 7 normal-weight) participated in an acute HIIE protocol (30 min, 4x4min @ 80% - 90% of VO) on a treadmill. Between HIIE intervals, subjects performed 3 min of active recovery at 50-60% VO. Blood samples were collected prior to, immediately following exercise, and one hour into recovery for measurements of plasma cfDNA and IL-6.

Key Findings: Our results demonstrated a significant elevation in plasma cfDNA immediately following acute HIIE in both obese and normal-weight subjects. A comparable elevation in the concentration of plasma IL-6 was also found between two groups in response to acute HIIE. Furthermore, the level of plasma cfDNA was not correlated with IL-6 either at baseline or in response to acute HIIE.

Significance: These findings may support the utilization of HIIE as a time-efficient exercise protocol to understand the obesity-associated cfDNA and inflammatory responses.