Introduction

Interval training, the secret weapon of coaches and athletes for over a century, holds the key to unlocking peak performance. This powerful exercise technique has sparked the curiosity of countless scientists, thanks to its incredible ability to ignite profound physiological adaptations and deliver health benefits akin to moderate-intensity continuous training (MICT) in a fraction of the time. But here’s the kicker: the magic lies not only in the workouts’ intensity but also in the captivating dance between effort and rest, fueling the body’s remarkable transformation. So brace yourself for an exhilarating journey into the world of interval training!

Are you ready to discover this workout phenomenon that’s taking the fitness world by storm?

Say hello to HIIT, short for High-Intensity Interval Training! It’s a turbocharged training method that will push your limits and leave you breathless. Picture this: explosive bursts of heart-pounding, sweat-drenched intensity, followed by brief moments of rest or easier exercises. It’s a thrilling dance between pushing yourself to the limit and catching your breath. 

In scientific terms, HIIT is about finding that perfect work-to-rest ratio for your exercise session. We’re talking “near maximal” or “all-out” effort, where you give it your absolute best, reaching at least 90% of your maximal oxygen uptake or a whopping 75% of your maximal power. Hold on tight because research has shown that HIIT triggers a cascade of physiological changes that supercharge your fitness and metabolic health. Whether a clinical case or a healthy warrior, HIIT has your back, paving the way for a stronger, fitter, and healthier you by improving your exercise capacity.

What is HIIT?

HIIT is a training form characterized by short bursts of repeated, intense activity with periods of rest or low-intensity exercise. In technical terms, this is also written as the work-to-rest ratio for the exercise session. The format is performed with a “near maximal” or “all-out” effort corresponding to ≥90% of maximal oxygen uptake or >75% of maximal power. 

Research has indicated that HIIT induces multiple physiological adaptations that improve exercise capacity and metabolic health in both clinical and healthy populations.

Types of HIIT

Prepare to dive into the thrilling world of Interval Training and discover the different flavours that will push your limits and ignite your inner athlete! 

First, we have the renowned HIIT, which stands for High-Intensity Interval Training. It’s all about giving it your all, reaching ≥90% of your VO2 max or a whopping >75% of your maximal power. But wait! What are VO2 max and maximal power? VO2 max is the maximum amount of oxygen your body can use during intense physical activity. Maximal power is the highest rate at which the work is done. These are measured in a lab or a fitness centre with the help of specific equipment. So now, let’s get back to HIIT. Think of it as a challenge where you’ll be pushing yourself from “hard” to “very hard” on the rate of perceived exertion scale. Each intense effort will last a few seconds to several minutes, depending on how much you’re willing to give. But don’t worry. We’ve got your back with rest or less intense periods sprinkled in between. 

Let’s take things up a notch with the sprint interval training (SIT) model. This one is not for the faint of heart. We’re discussing going all-out, surpassing your VO2 max or maximal power. Picture short bursts of explosive activity lasting no more than 30 seconds, followed by relatively long recovery periods of around 4 minutes. It’s like a heart-pounding rollercoaster ride, with each high-intensity round leaving you breathless. For instance, imagine hopping on a cycle ergometer and pedalling like a maniac for 30 seconds, pushing against a force equivalent to a mind-boggling 170% of your VO2 max. But don’t worry; you’ll get a breather during the rest intervals or light exercise.

Lastly, let’s explore the exciting world of repeated-sprint training (RST). Brace yourself for lightning-fast sprints, each lasting less than 10 seconds. Compared to the recovery periods of SIT, these intervals will be relatively shorter, lasting less than 60 seconds. Repeated-sprint training is the secret weapon of athletes across various sports, helping them prepare physically for the challenges ahead. While the published literature may be less extensive for RST, one thing is for sure: the recovery periods in HIIT are designed to allow for almost complete rejuvenation of your sprint performance. However, in RST, the recovery duration between sprints is minimal, which means you’ll inevitably experience a decrease in performance. Nevertheless, it’s a thrilling balancing act that will push you to your limits.

Get ready to choose your adventure and embark on an exhilarating journey into Interval Training. Whether you’re craving the explosive energy of HIIT, the all-out madness of SIT, or the lightning-fast sprints of RST, one thing is sure: you’re in for a heart-pumping, sweat-drenched, and exhilarating experience!

References

• 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.