Acute and Chronic Effects of a High-Intensity Interval Training Shock Microcycle on Cell-Free DNA: A Randomized...

Area of Science:

• Exercise Physiology
• Biochemistry
• Sports Science

Background:

• Investigated acute and chronic exercise-induced changes in cell-free DNA (cfDNA) concentrations.
• Focused on a 7-day high-intensity interval training (HIIT) shock microcycle in trained endurance athletes.
• Compared HIIT-only (HSM) and HIIT plus low-intensity training (HSM+LIT) groups against a control group.

Purpose of the Study:

• To evaluate acute and chronic exercise-induced changes in cfDNA concentrations.
• To assess cfDNA as a marker of exercise stress and adaptation.
• To correlate cfDNA levels with physiological exercise variables.

Main Methods:

• Administered 10 HIIT sessions over 7 days, with one group receiving additional low-intensity training.
• Collected venous blood samples at rest and post-exercise (0 and 30 min) on specific intervention days.
• Measured cfDNA fragments (90 and 222 bp) and performed physiological exercise testing (PET) at multiple time points.

Main Results:

• Significant increases in cfDNA (90 and 222 bp) were observed immediately after PET and HIIT sessions.
• cfDNA levels remained elevated 30 min post-HIIT, with higher concentrations after afternoon HIIT sessions.
• Moderate correlations were found between cfDNA90 and peak power output (PPO), lactate threshold (LT), and VO₂max.

Conclusions:

• cfDNA serves as a reliable indicator of acute exercise-induced stress in athletes.
• The study suggests limited potential for cfDNA in detecting chronic adaptations from short-term HIIT protocols.
• Further research may explore cfDNA's role in different training contexts and durations.