By Daniel Heller, MSc, CSCS, RSCC
High-intensity interval training (HIIT) is in vogue. Part of its appealing nature is the relatively short time commitment. But there’s more to it. HIIT combines short, high-intensity rounds (rate of perceived exertion [RPE] 9-10 for 30-90 seconds) with very low-intensity rest periods (RPE 2-3 for 30-90 seconds) to recover for the next intense round and/or exercise for a total duration of about 25 minutes. This doesn’t include warm-up and cool-down, which adds another 20 minutes. For those who get little pleasure from moderate-intensity, long-duration physical activity, HIIT is an excellent alternative because it yields similar benefits.1 You won’t get bored.
High-intensity is not for everyone. The feelings associated with a maximum effort physical activity are not always pleasant; for example, a temporarily increased heart rate is sometimes unpleasant when you’re unaccustomed to it. Your commitment to your physically active life should bring pleasure and joy, so let the pleasure guide your exercise choices.2 Read on for benefits of HIIT and how to do it safely.
What are the benefits of HIIT?
When HIIT is combined with a healthy diet, like Mediterranean-style eating or Paleo, it can yield an increase in muscle mass while decreasing adipose tissue (improve body composition).3 You’ll potentially lose a couple of sizes and look leaner. HIIT has been researched for several health benefits such as supporting cardiovascular health and blood sugar balance.4 Even though the time commitment is a few minutes shorter than a standard low-/moderate-intensity, steady-state workout, it still requires commitment to gain the benefits.
What does high intensity feel like?
Recalling the earlier article that discussed exercise intensity, we used several rates of perceived exertion scales (RPE). For high intensity we’re looking at > 8, and for low intensity (rest period) < 4. Liking or disliking the feeling of high intensity effort should be an indicator of whether this is right for you or not.2,5 Feeling your heart rate rise above resting state has benefits and is important for supporting a healthy cardiovascular system. Remember that uncomfortable sensations are only brief, and you’ll have equal time to recover before it happens again.
Staying safe: warming up, cooling down, and being attentive
As with all exercise routines, we must take precautions to ensure our safety. Warming up and cooling down for HIIT is just as important as for any other type of workout. Warming up properly is for safety reasons. This is especially true when doing a maximum-effort physical activity like high-intensity interval training. The physiological changes that occur during a warm-up include an increase in heart rate, connective tissue pliability, movement coordination, and muscles’ ability to produce force, meaning you’ll simply be able to move more freely and feel strong.6,7 Cooling down after an intense workout is the first step to the recovery process so you’re ready for your next HIIT workout within 48 hours. As your body cools down from the workout, you’ll notice your heart rate steadily drops to how you feel during rest, and you’ll physically feel cooler.7
Being mindful of how you’re feeling during HIIT is crucial to keeping it safe because when fatigue sets in, technique can be compromised.8,9 A common fatigue sign is difficulty focusing on your workout. The risk of injury increases as attention to technique decreases. Each bout of high-intensity effort will leave you feeling winded, and the recovery period will prepare you for the next interval. If you are new to HIIT, choosing low-risk exercises such as a stationary bike can keep you safe because you’re in a seated position, and the risk of technique error is low.10
Types of HIIT: Session goals, exercises, and intention
Simple vs. complex exercises can determine the intensity of the HIIT training session. For example: Simple HIIT can use a stationary bike as in the sample workout below. A complex HIIT workout would include free weight exercises. Complex exercises can potentially increase risk of injury. Choose something you’re comfortable with, like a stationary bike, walking, running, or a rowing machine. In this example, the choice of a cycle is used because it is generally a nonimpact exercise method, is easily adapted to age, and offers the opportunity to experience “pushing” yourself. Most fitness facilities have a stationary bike of some sort. More complex exercises can be implemented using this similar time pattern.
- Warming up: ~ 10 minutes
- Cooling down: ~ 10 minutes
- Adding these elements to a 25-minute HIIT workout extends the length of the session by 20-25 minutes, bringing it to around 40-50 minutes
Example HIIT workout
|Warm-up||5-min. walk at RPE 3-5, then 5-min. cycle at RPE 3-5||10 minutes|
|Rounds 1-10||60-sec. cycle at RPE 8-10, then 60-sec. cycle RPE 2-4||2 minutes each|
|Cool down||Self-soft tissue work—foam rolling and stretching||10 minutes|
Key takeaway: Find a physical activity you enjoy doing that you’ll do on a consistent basis. Whether you participate in HIIT or consistent moderate intensity physical activity, your health will benefit. Enjoyment is the key to establishing a successful routine. Experiment with different exercise types to find what you like. What type of exercise and/or physical activity delivers that “WOW” feeling? Does it convert to HIIT?
Until next time, live well & live active.
Before starting any exercise program, please consult your healthcare practitioner.
1. Kong Z et al. PLoS One. 2016;11(7):e0158589.
2. Elsangedy HM et al. Med Sci Sports Exerc. 2018;50:1472-1479.
3. Smith MM et al. J Strength Cond Res. 2013;27:3159-3172.
4. Campbell WW et al. Medicine and science in sports and exercise. 2019;51:1220-1226.
5. Olney N et al. The Journal of Strength & Conditioning Research. 2018;32:2130-2138.
6. Buttifant D et al. The Journal of Strength & Conditioning Research 29: 656-660, 2015.
7. McArdle WD et al. Exercise physiology: nutrition, energy, and human performance. Lippincott Williams & Wilkins, 2010.
8. Fiorenza M et al. Medicine and science in sports and exercise. 2019. [Epub ahead of print.]
9. Romero-Arenas S et al. The Journal of Strength & Conditioning Research. 2018;32:130-138.
10. Kellogg E et al. J Strength Cond Res. 2018. [Epub ahead of print.]