What is HIIT, HIET, HIIE, or SIT?
Before we get into the description, let’s first break down these abbreviations so we know what they mean.
- HIIT = High Intensity Interval Training
- HIET = High Intensity Exercise Training
- HIIE = High Intensity Intermittent Exercise
- SIT = Sprint Interval Training
HIIT, HIET, HIIE, and SIT are all essentially the same thing. They are abbreviations for a specific type of training modality. For the rest of article, I will use the acronym HIIT so I don’t keep repeating the previously listed abbreviations. HIIT is a form of cardiovascular exercise that is based around timed intervals and varying intensity levels. This method of training typically features a short and intense anaerobic exercise (such as sprinting on a treadmill, bicycle, or rower), followed by a lower intensity recovery period.
The duration of the high intensity segment and the recovery period often ranges depending on the specified training program and an individual’s physical abilities. The cycle of high intensity to low-to-moderate intensity can be repeated as many times as one can handle. I have seen people train using high intensity interval training in a 4-10 cycles range. I have also seen programs that include HIIT lasting from anywhere between 5-30 minutes. I usually teeter around the 20-25 minute range when using this exercise strategy as it can be pretty challenging, especially for untrained individuals. This is what an example of a 20 minute 1:1 work-to-rest ratio HIIT workout looks like:
- 45 second sprint at 10 mph
- 45 second walk at 3.5 mph
- Repeat cycle for 20 minutes
So, why should you be doing high intensity interval training? Well, there are numerous health benefits to including HIIT in your workout regimen. Scientists have researched HIIT and its effects on the human body time and time again. There is no shortage of scientific evidence backing the positive effects of high intensity interval training on health. More information on high intensity interval training.
1. HIIT Is More Efficient for Weight Loss and Improving Aerobic Performance than Steady-State Endurance Training
An interesting study was conducted at the University of Western Ontario in 2011 where scientists had 10 men and 10 women train three times a week for six weeks. One group did HIIT that prescribed 30 seconds of all-out sprints followed by a 4-minute recovery period with 4-6 bouts per session. The second group practiced endurance training (ET) where they exercised for 30-60 minutes at 65% of VO2Max (the popularized “fat burning zone”).
The results were astonishing. Referencing the table below, despite committing far less time exercising (12-33 minutes less), the group that did HIIT saw similar changes that the ET group observed in body composition, VO2Max, and performance adaptations.
| Training Modality | High Intensity Interval Training (HIIT) | Endurance Training (ET) |
| Time Spent Exercising | 18-27 minutes | 30-60 minutes |
| Change in Fat Mass | Decreased 12.4% | Decreased 5.8% |
| Change in Lean Mass | Increased 1% | Increased 1% |
| Change in Time Trial | Increased 4.6% | Increased 5.9% |
| Change in VO2Max | Increased 11.5% | Increased 12.5% |
Another study done at McMaster University on short-term sprint interval versus traditional endurance training also showed similar findings. Scientists had eight men assigned to high intensity interval training and another eight assigned to endurance training. In this study, the HIIT group showed similar, if not better, changes in time trial, muscle buffering capacity, muscle oxidative capacity, and resting muscle glycogen content post-training.
2. High Intensity Interval Training Is Convenient, Cheap, and Can Even Be Free
The fact that you can do HIIT anywhere is another reason why it’s such a desirable form of exercise. Unless you live in box surrounded by a moat, you could literally step outside your house or apartment and right onto your concrete, grassy, asphalt, or dirt road gym. You can throw the “but a gym membership fee is not in my budget” complaint out the window and get into HIIT to improve your aerobic capacity and efficiently burn calories for free, financially speaking. If you’re just sprinting and walking, high intensity interval training doesn’t require pricey equipment either, which is an added money-saving benefit. If you fancy equipment, however, you can do HIIT with a jump rope, a rower, or a bike.
3. HIIT Intensifies Your Workout and Reduces Your Cardio Time
There are two types of people in this world – those who love cardio and those who absolutely hate cardio. For those of you who truly enjoy cardiovascular training – whether it be biking, running, jump roping, etc. – HIIT can be a great way to change up your routine. High intensity interval training can be applied in multiple ways to intensify your workout. It can be incredibly challenging and quite rewarding when your body begins to adapt to this new stressor. Progress can be one of the most addicting and enjoyable things to chase after. Once you begin to get stronger, sustain shorter rest intervals, and run, row, jump, or bike faster than you have before, you just might get hooked.
For those of you who would rather chew your arm off than slave away on a treadmill or stationary bike, high intensity interval training may be the answer for you to improve your cardiovascular health or lose fat without hours of boring cardio. As seen in the results from the scientific study in the table above, you can achieve similar, if not better, results with HIIT than you would if you were performing steady-state endurance training. In fact, according to the study, HIIT was actually more effective in reducing fat mass than steady-state endurance training. So say goodbye to the endless hours of cardio. HIIT it and quit it, baby!
4. Additional Health Benefits of High Intensity Interval Training
According to High-Intensity Intermittent Exercise and Fat Loss, published in the Journal of Obesity in 2011, Stephen H. Boutcher reviews multiple studies surrounding the effects of HIIT on health and fat loss. He references over 60 other articles and studies that implicate the following findings on high intensity interval training and its health benefits. While we still lack a comprehensive understanding of the specific mechanisms that cause fat reduction brought on by HIIT, we cannot ignore the positive outcomes of regular high intensity interval training.
- Regular HIIT has been shown to:
- Significantly increase both aerobic and anaerobic fitness
- Materially lower fasting insulin and insulin resistance
- Enhance skeletal muscle adaptations
- Improve skeletal muscle fat oxidation
- Improve glucose tolerance
High intensity interval training is a great exercise strategy to include in your workout routine for all the reasons listed above. Studies show that it is more effective in burning fat and improving aerobic fitness than steady-state endurance training. It can also be cheap, equipment-free, and possibly fun. Try throwing in a 15-20 minute session or two per week for a few months and see how you like it. Track your progress, and feel free to comment below as I’d love to hear about your experience!
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