In the last blog about Moving With Your Times we talked about Time (efficiency), Function, and Specificity as important factors to consider when adapting your exercise plans over the years.
Today we’re going to look at Specificity as it relates to someone who is prediabetic, as it allows us to ask the question: what kind of workouts should someone in this cohort be doing to help with their specific health goals?
It turns out research has been done that shows short sprint intervals have a statistically significant impact on insulin sensitivity.
From the study: “Thirty one healthy adults were randomly assigned to one of three conditions: (1) SIT (n= 12): six sessions of repeated (4–7) 30 s bouts of very high-intensity cycle ergometer exercise over 14 days; (2) sedentary control (n= 10); (3) single-bout SIT (n= 9): one session of 4 × 30 s cycle ergometer sprints.”
To summarize: the test group consisted of 12 total people, either sedentary or up to 3x/week moderate exercisers. On average they were normal to slightly overweight, of low to average aerobic capacity, but otherwise healthy.
For their test workouts they did 30 second sprint intervals (at ~90% max HR) x 4-7 sets with 4 minutes of rest between each set. They did this on 6 unique days over a 14 day period. This is a pretty modest amount of work from my perspective of what I normally write in an hour session for my clients.
They also had two control groups: people who just did their normal exercise routine (no sprinting), and a “single bout” test group that did only one workout (72 hrs before re-testing) consisting of 4 sets of the sprint interval described above (30 sec on x 4 sets, 4 minutes rest between sets). This was to identify or exclude the possibility of an acute response to sprinting that didn’t depend on regular use of it.
From the study Discussion: “The novel findings of this investigation are: (1) short-term sprint interval training increased insulin sensitivity, as assessed using the gold-standard hyperinsulinaemic euglycaemic clamp technique.”
This is a big deal for several reasons:
- Specificity: If a person’s goal is to improve their insulin sensitivity, we now have a workout modality that can target that goal based on evidence. We’re doing more than burning calories and building strength, and then hoping that the stars align with their nutrition and lifestyle choices to give the results they want. It’s empowering for both the client and the coach.
- Enjoyment: I started testing these methods out about 2 years ago, first on myself and then on a few clients. I was expecting that I might enjoy sprinting because I like shorter workouts in general, but wasn’t sure how it would translate to others.
I was pleasantly surprised to find that most people like doing these short sprints, and even prefer them. There is something exhilarating about going all out for short periods of time, and the discomfort mostly happens after the interval is done, so there is an intensity level or “gear” people tap into that is often avoided because in a longer workout it would cause problems.
There are also so many different varieties of intervals we can create in the 0:10-30 second time range, boredom is not an issue. - Trackability: It is very straightforward to design, track, and progress sprint intervals on a C2 Rower, Bike, Treadmill, or any kind of machine that gives good performance data (Power via Watts, or Speed via m/s, mph, etc.). It is motivating to see what you’ve done in several past sessions and work to shave off 0.1 seconds, or hit a new wattage/power level.
- Safety: Absent a medical condition that would preclude aerobic exercise in general, it is very safe to sprint on a rower or bike. The technique and coaching requirements are minimal. A decent progression is recommended to introduce someone new, and each session should start with some lower intensity work (3-5 min warm-up), but otherwise we’re good to go.
- Repeatability: This study was done for just 2 weeks. Over a longer period of time, there is a lot we can do to multiply this out and make progress for someone with a specific goal like this. And because we have reliable performance metrics, once again we are empowered.
I will note that the study also concluded that “short-term sprint interval training did not affect resting energy expenditure or the thermogenic response to β-AR stimulation.” That post-workout burn that is often referred to as the justification for HIIT training in general… needs more data, or at least wasn’t shown to be the case in this particular study. Nutrition and lifestyle still matter, but now you hopefully have one more tool in your toolbox to take control.
Coach Mauricio