What is HIIT and Its Benefits for Those with Type 2 Diabetes?

So, you’ve heard the buzz in the media about HIIT, its impact on weight loss and cardiovascular benefits and are wondering, could HIIT be for me?  As a diabetic, someone with insulin resistance or one at high risk for either, you have likely heard the benefits of exercise, its impact on your blood sugar, and how your weight plays a role in all of it. However, you may be wondering is this safe? What should I do? How do I get started? What should I know?

There are four huge reasons to incorporate HIIT into your regimen (assuming you’re cleared by your physician).

• It can improve insulin sensitivity (resistance)¹
• Improves cardiovascular health and reduces risk of cardiovascular disease (CVD)⁵
• HIIT burns more calories per minute compared to Moderate Intensity Continuous Training (MICT) ⁶
• Requires less time per session to receive the same or increased health benefits

What Exactly is HIIT?

HIIT stands for high intensity interval training. There are many HIIT program variations but what makes a program HIIT is that it has an element of high intensity exercise, and an element of low to moderate intensity exercise executed in revolving intervals.  An example is if someone used an exercise bike they might bike as fast as they can for 20-30 seconds, and immediately afterward slow down to a slow to moderate pace for 1-2 minutes. They might repeat these timed intervals for a period of 10-30 minutes. HIIT can take many different forms and incorporate various high intensity intervals, as well as various different types of exercises. Therefore, there may be some HIIT programs that are appropriately challenging and yielding a multitude of benefits and others that may be excessively intense or place too much stress on the joints. Here’s what you need to know: how to gauge your levels of intensity, HIIT program options, and what programs may be appropriate for you (with clearance from your physician), and things to be aware of.

Let’s Talk About Intensity

Intensity refers to the level of exertion of the heart. Vigorous/High intensity can be defined as activity that is at 6 or more METs (metabolic equivalents).⁸ However, this definition is not practical for the everyday participant. A more practical way of identifying the level of intensity that you’re working at is illustrated below:

1. Light – This exercise creates a barely noticeable change in breathing, involving the beginning of an increased depth of each breath.
2. Moderate – Activity that requires increased breathing but you can still carry on a conversation.
3. Vigorous – Activity that is demanding to the point that talking cannot be maintained during activity.
4. High – This is near maximal effort, and can only be sustained briefly.⁸

HIIT Program

As mentioned HIIT programs come in many different layouts, shapes and sizes. In most studies they use walking or biking as the exercise and use various rest, or active recovery intervals (very/light intensity recovery exercise). For example, in one study they had one group of participants perform one min high intensity biking followed by one minute of rest, which repeated ten times. They had a second group that performed two minutes of high intensity biking followed by one minute of rest, which repeated five times.³ In another study they took a group and used a range of 15-60 seconds of high intensity exercise followed by one minute of active recovery.⁶ The training sessions conducted in these studies typically lasted approximately 20-30 minutes and yielded better results than the moderate intensity continuous training (MICT) protocols they were compared to.⁶ The MICT done in the study was biking at a steady pace at a moderate level of intensity for up to 45 minutes. This illustrates just how much more effective HIIT can be than traditional cardio.

However, to be clear HIIT training is not appropriate for everyone, and if any doubts remain be sure to contact your physician. The American Diabetes Association recommends a 12-point electrocardiogram be performed on those with type II diabetes prior to beginning a vigorous training program, and while HIIT is not a prolonged vigorous training regimen, you should consult with your physician as a precaution.⁷

What Programs are Appropriate for You?

While some critics of HIIT argue that the high intensity increases participant dropout rates, the truth is you won’t know if it’s enjoyable or even tolerable unless you give it a try. Additionally, you may not like one HIIT program, but may find you like another. In all cases, it is recommended that you start at either a moderate or light intensity gradually increasing to higher intensities over time.⁸

What should I be aware of when undergoing a HIIT program

Specific to type II diabetes, you should be aware of:

• Any medical restrictions that apply to you, especially if you have additional chronic conditions in addition to diabetes
• How your blood sugar is affected and how to apply this to proper medication dosages
• Qualifications of the instructor carrying out the program
• Allowing your instructor to be aware of your health status or condition(s)
• Find out if there are any high orthopedic stress or ballistic movements, in the program you’re considering. If you’re just starting (i.e. you have not been conditioning for a minimum of month), movements you may want to avoid in the beginning are:
  • High knees, jumping lunges, jumping squats, running/sprinting, and any movement that pounds on your joints

Consideration Regardless of Exercise Type

There are times when you should not exercise on a given day such as:

• If you have a fever (over 101F)
• If you have a new illness that has not been treated
• If ambient temperature and humidity are excessive
• If exercise causes pain⁸
• If you have infection/mucus in the lungs

There may also be times when you should stop exercising and/or ask for guidance such as:

• If you feel chest discomfort
• If you unexpectedly have an irregular heart rhythm
• If you feel dizziness or lightheadedness during exercise, or you have dizziness or lightheadedness that does not resolve after you stop exercising
• If you experience leg cramps that persist after stopping exercise
• If your vision is blurry⁸

In Closing

HIIT has proven to be an effective training protocol that can yield heightened health benefits in less time than traditional moderate intensity continuous training (MICT). For those with type II diabetes, insulin resistance, or are at increased risk of either, HIIT can help you increase insulin sensitivity, reduce cardiovascular risk, and be an effective part of a weight loss program. Like any exercise program it comes with a measure of risk and is not suitable for everyone. Participate within the parameters set by your physician, and be sure to listen to your body.

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Jeremy Kring holds a Master’s degree in Exercise Science from the California University of Pennsylvania, and a Bachelor’s degree from Duquesne University. He is a college instructor where he teaches the science of exercise and personal training. He is a certified and practicing personal/fitness trainer, and got his start in the field of fitness training in the United States Marine Corps in 1998. You can visit his website at jumping-jacs.com

References

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2. Marcinko, K., Sikkema, S. R., Samaan, M. C., Kemp, B. E., Fullerton, M. D., & Steinberg, G. R. (2015). High intensity interval training improves liver and adipose tissue insulin sensitivity. Molecular Metabolism, 4(12), 903–915. http://doi.org/10.1016/j.molmet.2015.09.006
3. Smith-Ryan, A. E., Trexler, E. T., Wingfield, H., & Blue, M. N. M. (2016). Effects of high-intensity interval training on cardiometabolic risk factors in overweight/obese women. Journal of Sports Sciences, 34(21), 2038–2046. http://doi.org/10.1080/02640414.2016.1149609
4. Shepherd, S. O., Wilson, O. J., Taylor, A. S., Thøgersen-Ntoumani, C., Adlan, A. M., Wagenmakers, A. J. M., & Shaw, C. S. (2015). Low-Volume High-Intensity Interval Training in a Gym Setting Improves Cardio-Metabolic and Psychological Health. PLoS ONE, 10(9), e0139056. http://doi.org/10.1371/journal.pone.0139056
5. Phillips, B. E., Kelly, B. M., Lilja, M., Ponce-González, J. G., Brogan, R. J., Morris, D. L., … Timmons, J. A. (2017). A Practical and Time-Efficient High-Intensity Interval Training Program Modifies Cardio-Metabolic Risk Factors in Adults with Risk Factors for Type II Diabetes. Frontiers in Endocrinology, 8, 229. http://doi.org/10.3389/fendo.2017.00229
6. Jung, M. E., Bourne, J. E., Beauchamp, M. R., Robinson, E., & Little, J. P. (2015). High-Intensity Interval Training as an Efficacious Alternative to Moderate-Intensity Continuous Training for Adults with Prediabetes. Journal of Diabetes Research, 2015, 191595. http://doi.org/10.1155/2015/191595
7. Francois, M. E., & Little, J. P. (2015). Effectiveness and Safety of High-Intensity Interval Training in Patients With Type 2 Diabetes. Diabetes Spectrum : A Publication of the American Diabetes Association, 28(1), 39–44. http://doi.org/10.2337/diaspect.28.1.39
8. Moore, G. E., Durstine, J.L., & Painter, P. (2016). ACSM’s exercise management for personals with chronic diseases and disabilities. Champaign, IL: Human Kinetics.