Unravelling the Science and Benefits of HIIT: Part 2

Unravelling the Science and Benefits of HIIT (High-Intensity Interval Training) - Part 2

Let’s take a plunge into the realm of high-intensity interval training (HIIT) and unlock its incredible potential. Over the past decade, HIIT has captivated researchers and fitness enthusiasts alike, revealing its ability to deliver impressive results. For example, recent data demonstrate that compared to moderate-intensity continuous training (MICT), just six weeks of HIIT can trigger similar enhancements in maximal oxygen uptake (VO2max) and mitochondrial function. But that’s not all! Some studies suggest that HIIT goes above and beyond, outperforming MICT regarding VO2 max improvements.

So, what does science say about HIIT? 

Not only does HIIT offer exceptional benefits, but it also ignites a higher level of enjoyment. Original research and meta-analyses resoundingly report that the interval training approach wins over the hearts of the general population. Yes, you read that right – HIIT is both practical and enjoyable!

Moreover, a comprehensive meta-analysis by Reljic et al. in 2019 revealed that HIIT-based interventions have lower dropout rates than traditional exercise programs, making it a tolerable fitness model. However, a word of caution: subjecting yourself to a single bout of HIIT at a grueling intensity with inadequate rest periods can dampen the joy. It is crucial to incorporate sufficient resting intervals between training sessions to maintain long-term exercise adherence.

A growing body of evidence-based research has uncovered the multitude of benefits that interval training programs can deliver, ranging from 5 days to 12 months. Let us explore some of the benefits:

  • Boost in VO2max
  • Enhanced endurance capacity
  • Elevated resting metabolic rate
  • Optimized substrate metabolism
  • Improved body composition
  • Enhanced insulin sensitivity
  • Sharpened cognitive functions

That’s not all! Interval training has also emerged as a formidable weapon against cardiovascular diseases, breast cancer, metabolic syndrome, osteoarthritis, and rheumatoid arthritis – known culprits behind lower back pain.

Who is it for or not?

You might be wondering if HIIT is a feasible option for everyone. While HIIT demands less time than MICT, it’s worth noting that the shortness of breath and overwhelming fatigue experienced during these intense sessions may be less tolerable for specific individuals, especially if they are beginners who need to first work towards having a good base. Therefore, its acceptance is not universal despite practical evidence showcasing significant adaptations and potentially greater enjoyment with HIIT.

However, if you are pressed with a time crunch, HIIT comes to the rescue! According to the recommended guidelines, adults should aim for 150 minutes per week of moderate-intensity continuous exercise (MICT) or 75 minutes of vigorous exercise to mitigate health risks. However, lack of time remains a formidable barrier, deterring approximately 50% of individuals from adhering to exercise programs within the first six months. Research has highlighted that factors such as fun, time availability, and intrinsic motivation significantly impact an individual’s commitment to a training regimen. In such circumstances, time-efficient exercises like HIIT emerge as a promising alternative to MICT, offering substantial health benefits.

Key takeaways: 

In conclusion, the importance of regular exercise for a healthy life is well-documented. Yet, time constraints often hinder our pursuit of fitness. Thankfully, interval training models rise to the occasion, delivering comparable health and performance benefits to MICT while demanding less time commitment. Among these models, HIIT shines bright, proving to be enjoyable and highly effective in eliciting remarkable physiological adaptations. So, why wait? Unleash the power of HIIT and make it a cornerstone of your regular exercise routine!


  • Atakan, M. M. et al. (2021) “Evidence-Based Effects of High-Intensity Interval Training on Exercise Capacity and Health: A Review with Historical Perspective,” International Journal of Environmental Research and Public Health, 18(13). doi: 10.3390/ijerph18137201.
  • Bishop, D. J. et al. (2019) “High-Intensity Exercise and Mitochondrial Biogenesis: Current Controversies and Future Research Directions,” Physiology, 34(1), pp. 56–70. doi: 10.1152/physiol.00038.2018.
  • Buchheit, M. and Laursen, P. B. (2013) “High-Intensity Interval Training, Solutions to the Programming Puzzle,” Sports Medicine, 43(5), pp. 313–338. doi: 10.1007/s40279-013-0029-x.
  • Gray, S. R. et al. (2016) “High-intensity interval training: key data needed to bridge the gap from laboratory to public health policy,” British Journal of Sports Medicine, 50(20), pp. 1231–1232. doi: 10.1136/bjsports-2015-095705.
  • MacInnis, M. J. and Gibala, M. J. (2016) “Physiological adaptations to interval training and the role of exercise intensity,” The Journal of Physiology, 595(9), pp. 2915–2930. doi: 10.1113/jp273196.
  • Oliveira, B. R. R. et al. (2018) “Affective and enjoyment responses in high intensity interval training and continuous training: A systematic review and meta-analysis,” PLOS ONE, 13(6), p. e0197124. doi: 10.1371/journal.pone.0197124.
  • Reljic, D. et al. (2019) “Prevalence and predictors of dropout from high‐intensity interval training in sedentary individuals: A meta‐analysis,” Scandinavian Journal of Medicine & Science in Sports, 29(9), pp. 1288–1304. doi: 10.1111/sms.13452.
  • Thum, J. S. et al. (2017) “High-Intensity Interval Training Elicits Higher Enjoyment than Moderate Intensity Continuous Exercise,” PLOS ONE, 12(1). doi: 10.1371/journal.pone.0166299.

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