Acute-Phase Inflammatory Response to Single-Bout HIIT and Endurance Training: A Comparative Study

Area of Science:

• Exercise physiology
• Immunology
• Biochemistry

Background:

• Single exercise bouts, including endurance training (ET) and high-intensity interval training (HIIT), can influence inflammatory markers.
• Understanding the acute and late effects of different exercise modalities on plasma cytokines and growth factors is crucial for optimizing training protocols and health outcomes.

Purpose of the Study:

• To compare the acute and late effects of a single bout of ET versus HIIT on plasma levels of inflammatory cytokines (IL-1β, IL-6, IL-10), monocyte chemoattractant protein-1 (MCP-1), insulin-like growth factor 1 (IGF-1), and C-reactive protein (CRP).

Main Methods:

• A cohort study with a repeated-measures design was conducted.
• Seven healthy, untrained volunteers completed one session of ET and one session of HIIT on a cycle ergometer in a randomized order, with at least 7 days between sessions.
• Blood samples were collected pre-intervention, 30 minutes post-intervention, and 2 days post-intervention. Plasma levels of IL-1β, IL-6, IL-10, MCP-1, IGF-1, and CRP were analyzed using ELISA, with statistical analysis performed using Wilcoxon signed-rank tests.

Main Results:

• Endurance training (ET) induced a significant acute inflammatory response, evidenced by a decrease in the IL-6/IL-10 ratio (-20%; p = 0.047) at 30 minutes post-exercise.
• A significant decrease in monocyte chemoattractant protein-1 (MCP-1) was observed at 30 minutes after ET (-17.9%; p = 0.03).

Conclusions:

• Single-bout endurance training (ET) elicits a more adverse acute inflammatory response at 30 minutes post-exercise compared to high-intensity interval training (HIIT).
• However, ET demonstrates a beneficial late effect with a significant reduction in MCP-1 at two days, which is associated with a reduced risk of atherosclerosis.