HIIT vs. MICT: Which Cycling Protocol Wins the Cardiovascular Race?

Complete Performance
Jun 13
3 min read

When it comes to optimizing your cardiovascular health, not all workouts are created equal. A recent case study from the Faculty of Sport, the University of Ljubljana, provides compelling evidence that High-Intensity Interval Training (HIIT) may be a more powerful catalyst for vascular health compared to Moderate-Intensity Continuous Training (MICT)—even after just a single session.

Let’s break down the science and explore how this could impact not just your fitness, but your business if you're in the health, wellness, or performance optimization space.

The ACT-ON Study: Science on the Saddle

In this case report, a healthy male subject (1.76 m, 80 kg) underwent two types of cycling sessions—MICT and HIIT—separated by baseline testing and rest periods. Each protocol’s impact was evaluated using advanced vascular and microvascular assessments, including:

Pulse Wave Velocity (PWV) for arterial stiffness
Augmentation Index (AIx)
Flow-Mediated Slowing (FMS) for endothelial function
Tissue Saturation Index (TSI) for microvascular reoxygenation

This wasn’t your average "feel-the-burn" fitness test. These metrics provide a window into how our arteries and microvasculature respond to different intensities of exercise—a crucial insight for anyone serious about heart health.

Key Findings: HIIT Stands Out

💓 HIIT = More Favorable Arterial Responses

Carotid-femoral PWV (cfPWV) improved more after HIIT, suggesting greater flexibility in central arteries, while
Brachial artery PWV (baPWV) increased substantially after HIIT.
This suggests distinct responses in central and peripheral arterial stiffness following exercise bouts of varying intensities.

🧬 Endothelial Function Boost

FMS% showed a greater increase post-HIIT, pointing to better endothelial function—a key marker of cardiovascular health and longevity.

🔬 Better Microvascular Recovery

The TSI reoxygenation slope after HIIT was double that of MICT, indicating a superior recovery of microvascular function.

⚖️ MICT Has Its Place—But Less Potent Acutely

AIx increased slightly after MICT, potentially reflecting a less favorable arterial reaction in the short term.

Business Insight: Why This Matters for Entrepreneurs

If you’re a fitness coach, physiologist, or health tech founder, these findings could influence everything from app algorithms to personalized training plans. Consumers want fast, effective results. The data suggest that HIIT may provide greater acute cardiovascular benefits than MICT—a message worth integrating into your brand or client protocols.

And for those in the biohacking or longevity space? HIIT could be your go-to protocol for clients who seek efficient, measurable vascular improvements with minimal time investment.

Conclusion: Train Smarter, Not Just Harder

This case study reinforces a growing body of evidence: exercise intensity is a key determinant of vascular response. HIIT not only pushes performance limits but delivers superior short-term improvements in both endothelial and microvascular function.

While MICT remains valuable for endurance and active recovery, HIIT might be the strategic edge your training—or your business—needs to stand out.

Ready to Revolutionize Your Training or Wellness Business?

Start leveraging scientifically-backed insights like these to tailor your services. Whether you’re crafting elite athlete programs or building the next-gen fitness app, one thing’s clear:

The future of cardiovascular health is intense—and interval-based. 📣 Keep updated for more robust findings from our ongoing randomized controlled study with an adequate sample size—coming soon!

Funding

This work was funded by the University of Ljubljana’s Development Fund (project IDs: 005-1/2023 and 802-15/2023-5, acronym [ACT-ON]), with assist. Prof. Armin Paravlic as the principal investigator. 🙏 Special thanks to all participants and my colleagues Simon Iskra, Gasper Turnsek, and Kristina Drole for their dedicated collaboration on this project.

✏️Author: Assist. Prof. Armin Paravlić, PhD