An old axiom says that good things may come in small packages – can the same be said for exercise? HIIT exercises take minimal time but appear to provide benefits in patients with type 1 diabetes.
Lifestyle changes are hard. Many people that have type 1 diabetes lead sedentary lives. A big fear they have with exercising is causing hypoglycemia. A common complaint is that there isn’t enough time to exercise. High-intensity interval training (HIIT) has been gaining popularity in recent years for its low time commitment. Studies have shown that HIIT improves vascular function without reductions in glycemia that are often associated with moderate-intensity exercise. These studies, however, were performed at a laboratory and under strict supervision, far from what most people would experience in their daily lives.
This study sought to examine the benefits of HIIT performed at home. 11 people with type 1 diabetes were recruited and completed 6 weeks of HIIT at home. At baseline, HbA1c was 8 ± 0.6%, BMI was 27.3 ± 1.6, and daily insulin dose was 0.31 ± 0.06 units per kilogram per day. The home HIIT program was completed in an unsupervised place of the participants’ choosing. A session was one minute of high-intensity exercise followed by one minute of rest. The goal was for the participant to get their heart rate ≥80% of their predicted maximum (220 – age). These one-minute-long exercises consisted of two, thirty second body weight exercises with no rest in between. Each participant was provided 18 exercises, with 9 suggested pairs and were free to choose their preferred exercises. It was suggested that each person train three times per week, starting with six of the one-minute sessions in the first two weeks, increasing by two sessions every two weeks. Participants were given a heart rate monitor that connected to their phone via Bluetooth. The results from each session were uploaded to the Internet, where both the participants and researchers could view results. These results allowed the researchers to see any sessions missed and to track compliance. Participants were advised to only exercise if their blood glucose was between 7 and 14 mmol/L (126-252 mg/dL) and were asked to measure their glucose levels before, after, and one hour after each session. They were also asked to record their use of added carbohydrates or insulin during or after each session. During the first day and final week of the program, participants were asked to measure their insulin dose and blood glucose before and two hours after each meal, just before bed, and again at 2 A.M.
Most patients were very compliant with their exercise regimens – adherence was 95 ± 2%, while most heart rates were at ≥80% of max in 99 ± 1% of sessions. Glucose remained constant during and after exercise, with the levels directly after and one hour after the exercise showing no statistically significant difference (P = 0.249). Carbohydrates were consumed in 10 of the 188 completed sessions (6 ± 3% of the sessions). Insulin was needed after 3 of the 188 sessions. There were no reports of severe hypoglycemic episodes. At the end of the six-week study, patients reported a decrease in their daily short-acting insulin of 13% (P = 0.012) with no statistically significant change in the mean blood glucose concentration (P = 0.445) and no significant change in BMI (P = 0.646).
A key strength of this study is that it looked at people with type 1 diabetes using HIIT in the comfort of their own homes. This decreases barriers to starting an exercise regimen, as there is no commute or membership fees associated with gyms. It is a small study, having only eleven participants. As such, there may be complications (or advantages!) from HIIT that were not seen. The relatively short study time of six weeks does not tell us the long-term effects of HIIT. HIIT did not significantly change BMI. If someone wishes to start exercising, they may have a desire to lose weight, which this regimen would not provide. With the top three reported barriers to exercise being lack of time (91%), fear of hypoglycemia (27%), and a lack of motivation (18%), these quick, high-intensity exercise sessions can provide a solution for these fears, as it is quick, does not result in significant changes to glycemic control, and increased participants’ motivation to exercise. The adherence rate was very high. Overall, the weekly time commitment was less than 60 minutes, meaning it is a quick way to squeeze in exercise, though it falls well short of the 150 minutes per week of recommended exercise, so it can augment, but not replace other exercise routines.
- HIIT at home provided a way for people to exercise quickly and without fear of social stigma.
- HIIT can be recommended if someone has a very busy schedule or is unable to attend a gym.
- HIIT resulted in a significant decrease in total daily short-acting insulin doses.
- There was no significant change in BMI after 6 weeks of HIIT.
- With no significant changes in mean blood glucose, HIIT can be recommended with minimal fear of causing hypoglycemia, though patients should still monitor their glucose levels.
Scott, Sam N., et al. “A Multidisciplinary Evaluation of a Virtually Supervised Home-Based High-Intensity Interval Training Intervention in People With Type 1 Diabetes.” Diabetes Care, American Diabetes Association, 1 Dec. 2019, care.diabetesjournals.org/content/42/12/2330.
George McConnell, PharmD. Candidate, LECOM School of Pharmacy