Diabetes is reaching epidemic proportions in the United States. According to the American Diabetes Association, nearly 10 percent of the population (25.8 million Americans) has diabetes, with just shy of 2 million new cases being diagnosed every year.
As if this isn’t frightening enough, another 79 million people have prediabetes, meaning they don’t meet the clinical definition of diabetes, but their blood glucose and insulin levels are dangerously elevated, putting them at risk of developing diabetes unless they change their lifestyle and dietary habits.
And with diabetes comes a whole host of life-threatening and life-changing complications, including:
- Heart disease
- Kidney disease
- Nervous system disorders
Given the seriousness and prevalence, it’s no wonder that researchers are motivated to find ways of managing diabetes. In addition to the plethora of oral and injectable medications, there are the obvious lifestyle solutions, namely diet and exercise.
Traditional exercise recommendations for managing diabetes have included low- to moderate-intensity exercise for at least 30 minutes a day five days a week. For many people, however, this recommendation is often not followed due to lack of time.
It is this barrier that Canadian researchers were hoping to overcome. Based on previous research, they hypothesized that low-volume, high-intensity interval training could be an effective and time-efficient exercise solution for people with diabetes.
Setting the Stage
Researchers recruited eight participants, all of whom had been diagnosed with type 2 diabetes for at least three months. None of the participants were taking insulin and none had end-stage liver or kidney disease, neuropathy, retinopathy or cardiovascular disease. Six of the eight participants were taking some form or forms of oral medication.
Researchers recorded height and weight, as well as a basic 15-minute walking test to determine cardiovascular capabilities and ratings of perceived exertion, which would be used to determine their level of intensity during the workout.
They also collected a number of biological samples before, during, and after the study. First was a continuous glucose monitoring (CGM) device insertion to monitor blood glucose levels. Participants were also given a glucose meter.
One day later, the participants were asked to eat a specific diet for 24 hours. This included a breakfast of their choice; snacks of almonds, fruit or vegetables; and lunch and dinner from a local sandwich restaurant. They were also asked to keep a detailed food diary of all food consumed during the pre-training days.
Two days later, participants had the CGM device removed and had a skeletal muscle biopsy, which involved taking muscle samples from their upper thigh or quadriceps (the vastus lateralis).
Finally, five days later, the training began. Participants had a total of six supervised training sessions over two weeks. All training sessions took place on Monday, Wednesday, and Friday, and consisted of the following:
- Three-minute warm up
- Ten 60-second high-intensity cycling intervals at about 90% maximum heart rate
- Ten 60-second low intensity rest periods between intervals
- Two-minute cool down
The entire exercise session took 25 minutes, and the high-intensity output was just 10 minutes a day or 30 minutes a week.
After the two weeks and six training sessions, researchers retested all participants. Forty-eight hours after the final training session, researchers once again gathered CGM data using the same 24-hour diet as pre-training. Seventy-two hours after the final session, they collected another muscle biopsy. Two to four days after that, they did another walk test and maximal exercise test.
Finally, they assessed the perceived enjoyment of the activity. They asked participants, on a scale from one to nine, with nine being very enjoyable, how much they would like engaging in a single bout of high-intensity training, and how much they would like engaging in high-intensity training at least three times a week for the next four weeks.
Fast and Infrequent May Be the Key
At the end of the study period, researchers found that while training didn’t have any significant effect on body mass or weight, there was a notable difference on both blood glucose and skeletal muscle protein content.
CGM data showed that the average blood glucose concentration decreased from 7.6 mmol/L to 6.6 mmol/L after training. Additionally, post-meal glucose levels were also lower after training, with levels dropping from 965 mmol/L to 679 mmol/L.
With skeletal muscle readings, researchers found that training helped to increase mitochondrial protein content. This is important, as reduced mitochondrial capacity is a hallmark of both insulin resistance and type 2 diabetes. Researchers hypothesize that increasing protein content and capacity may help make cells more insulin sensitive.
Researchers also found that, after two weeks, participants increased their maximal workload by 10 percent. They also showed reduced heart rate (from 73 to 66) and their rate of perceived exertion (from 2.4 to 1.3).
More importantly, their perceived enjoyment of high-intensity training was high across the board, with a single session garnering an 8.1 out of 9 and three times a week registering a 7.9.
Researchers concluded, “Two weeks of low-volume [high-intensity training] – involving only 30 min of vigorous exercise within a total time commitment of 75 min per week – lowered 24-h average blood glucose concentration, reduced post-meal blood glucose excursions, and increased markers of skeletal muscle mitochondrial capacity in individuals with [type 2 diabetes]… Our findings indicate that low-volume [high-intensity training] may represent a time-efficient exercise strategy for the treatment of [type 2 diabetes].”
Pick Up the Pace
High-intensity interval training has, once again, proven to be a very effective from of exercise. Best of all, you can achieve great results in a very short period of time.
Whether your goal is weight loss or managing diabetes, high-intensity training may be the way to go. You can use the exercise strategy laid out here (warm up, then (10) 60-second intervals of high-intensity cycling interspersed with 60-second rest periods, and then a cool down), or you can find other programs online.
The bottom line is to get moving, move quickly, and you won’t have to move as often to get the same results.
 Little, JP et al. Low-volume high-intensity interval training reduces hyperglycemia and increases muscle mitochondrial capacity in patients with type 2 diabetes. J Appl Physiol. 2011 Aug 25. [Epub ahead of print.]