I have personally found HITT training to be a mixed bag when it comes to blood sugar management. Some workouts can spike your blood sugar high, like a Strength/ Resistance training session. Others can drop you low, like an Endurance/Cardio session and some won’t have much of an effect at all.
HIIT training can have many different effects on blood sugar for T1 diabetics.
For short HIIT sessions 20-60 minutes, I usually don’t do anything differently than what I would normally do in daily life. I don’t typically reduce my basal insulin or eat in advance. As always, if I’m going low, I’ll eat. If I’m going high, I’ll correct with insulin.
For HIIT sessions that are longer than 60 minutes, I usually treat more like an Endurance/Cardio session since my average heart rate is elevated for a longer period of time. I find that in these cases my BGs tend to go lower.
For HIIT sessions that are 20 minutes or less, I treat it more like a Strength/Resistance session since they are usually really intense and are more likely to spike me high.
The past few years, most of my HIIT style workouts have been OrangeTheory Fitness classes. I find that most of the time, I can go through their 60 minute classes without doing anything special to manage my blood sugar. Their “Endurance” days (usually long blocks on the treadmill), I’ll occasionally need carbs and their “Power” days (very short intense bursts and lots of jumping) I’ll occasionally need to correct a high.
Occasionally, I’ll also do 400 or 800 repeats at the track or a fartlek session on the trails. In those cases, since I’m typically still running/jogging during the “recovery” periods, I usually treat this more like an Endurance/Cardio session as well.
Since there is so much variability with HIIT training, you might be wondering, “why bother?” but there are really so many benefits to this kind of workout. In my opinion, it is beyond worth it to figure out how to manage your blood sugar during HIIT style workouts.
The main benefit of HIIT training that most people seem to talk about is the “afterburn” meaning you’re not just burning calories during your workout but…
you actually continue burning calories for hours after your workout
This is because it takes longer for your metabolism to return to it’s normal rate* when you do high intensity intervals. Another benefit is that HIIT training is an extremely efficient way to train. You can burn a lot of calories in a relatively short amount of time. If you look back through my daily workouts, compare my calorie burn for 60 mins of strength, with 60 minutes of cardio, with 60 minutes of HIIT. Most of the time, the HIIT burns the most calories, then cardio and then strength**. Last but not least,
HIIT training improves insulin sensitivity***!
This is probably the biggest benefit to us as diabetics. While most of the time, I hear about how great this is for Type 2 diabetics; for Type 1 diabetics, becoming more sensitive to insulin means we can USE LESS INJECTED INSULIN for the same amount of food!!! Even though I’m lucky to have great insurance, the fact that many can’t afford this life sustaining medication is a tragedy. If there is any way to use less insulin (helping bring down the individual cost) without harming your health (and in this case improving your health) we need to be sharing this information as much as possible.
Most T1s I talk to are shocked when I tell them my Total Daily Dose (TDD, including all basal and bolus insulin) is typically around 20 units. That’s it, 20 units per day to keep my blood sugar within healthy range. I firmly believe that my “super sensitivity” to insulin is due in large part to the fact that I work out regularly and consistently**** and include HIIT as part of my training program.
Feeling inspired to give HIIT a try? The OTF YouTube channel has free home workout HIIT style videos.
*As opposed to moderate intensity cardio, for example.
**Of course, there are other benefits to cardio and strength training so don’t just write those off!
***All forms of exercise can do this but HIIT training is particularly good at this!
****I also use Time Restricted Feeding (TRF) and Intermittent Fasting (IF). IF has been shown to increase insulin sensitivity as well.
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The content on this site is not intended to be medical advice. Always consult your doctor before beginning a fitness regimen or adjusting your diabetes management strategy.