The Impact of Burst Exercise on Cardiometabolic Status of Patients Newly Diagnosed with Type Two Diabetes

Julia Lvovich, Mercer University College of Pharmacy

Exercise and diet are the cornerstones of treatment for type II diabetes. With proper adherence to non-pharmacologic therapy, it is suggested that symptoms of type two diabetes and micro and macrovascular complications may be controlled. According to the American Diabetes Association (ADA), “patients should undertake at least 150 min/week of moderate to vigorous aerobic exercise spread out during at least three days during the week, with no more than two consecutive days between bouts of aerobic activity”. [1] The ADA programs typically focus on long-duration, less intense types of exercise. Sustained exercise programs are associated with reduced blood glucose levels and body mass index (BMI) and improved lipid profiles. [1]

Contrary to the ADA programs, a growing amount of studies support a movement towards high-intensity interval training (HIIT) in people with type II diabetes. High-intensity interval training is defined as alternating between high intensity exercise (≥70 maximal aerobic capacity) and rest or active recovery. [2] This method has shown to be time efficient, but it is difficult to find the right regimen due to the patient population being older, obese, sedentary, and unwilling. Continuous burst-exercise regimen is one of the high-intensity exercise methods used; however, it has not been compared to moderate intensity continuous training. The study below was conducted to fill the gap in the knowledge. [2]

The impact of burst exercise on cardiometabolic status of patients newly diagnosed with type two diabetes
Design Randomized control trial; N=40
Objective To evaluate effects of multiple short-duration, high-intensity continuous burst exercise regimen on HbA1C levels in newly diagnosed type II diabetic patients after three months of exercise and compare the outcomes to that of moderate intensity continuous training (MICT)
Study Groups Moderate-intensity continuous exercise training (MICT) group (n= 19)

high-intensity interval training (HIIT) (n=21)

Methods Inclusion Criteria:

·       ≥18 years old

·       New onset (within three months) of type two diabetes

Exclusion Criteria:

·       Abnormal results of stress test

·       Presence of diabetic end organ damage; kidney, heart, cerebrovascular, or peripheral vascular disease

·       Inability or contraindication to preforming a stress test

·       Receiving hypoglycemic or lipid-lowering medications at any time during the study.

The patients were randomized into either a control group that included 40 minutes of MICT (60% of maximal heart rate) five days per week group, or to intervention group that included three continuous bursts of 12 minutes of high-intensity exercise (85% of maximal heart rate) five days per week for three months. Body mass index, hemoglobin A1C (HbA1C), and lipid profile were assessed before and after three months of exercise training. Using Bruce protocol the aerobic capacity was measured with a maximal capacity stress test.

Duration Three months
Primary Outcome Measure Change in hemoglobin A1C, BMI, LDL, HDL, and triglycerides.
Baseline Characteristics
Variable Control group

MICT (n = 19)

Intervention group

burst exercise (n = 21)

p value
HbA1C (%)
 Baseline 8.18 ± 0.35 8.14 ± 0.49 0.76
LDL (mmol/L)
 Baseline 3.31 ± 0.22 3.34 ± 0.20 0.68
HDL (mmol/L)
 Baseline 0.64 ± 0.07 0.61 ± 0.08 0.39
TG (mmol/L)
 Baseline 3.29 ± 0.25 3.35 ± 0.41 0.64
Non-HDL (mmol/L)
 Baseline 3.96 ± 0.23 4.01 ± 0.23 0.62
Minutes of exercise achieved on the Bruce protocol
 Baseline 5.47 ± 1.65 5.60 ± 1.41 0.81
METS achieved on the Bruce protocol
Baseline 5.35 ± 1.61 5.44 ± 1.37 0.81

MICT, moderate-intensity continuous exercise training, METS, metabolic equivalents; MICT, moderate-intensity continuous exercise training.

Results  

Variable Control group

MICT (n = 19)

Intervention group

burst exercise (n = 21)

p value
HbA1C (%)
 Baseline 8.18 ± 0.35 8.14 ± 0.49 0.76
 3 mo 7.94 ± 0.41 7.32 ± 0.39 < 0.001
 Change at 3 mo –0.25 ± 0.23 –0.82 ± 0.37 < 0.001
LDL (mmol/L)
 Baseline 3.31 ± 0.22 3.34 ± 0.20 0.68
 3 mo 3.15 ± 0.28 2.97 ± 0.16 0.01
 Change at 3 mo –0.16 ± 0.13 –0.37 ± 0.18 < 0.001
HDL (mmol/L)
 Baseline 0.64 ± 0.07 0.61 ± 0.08 0.39
 3 mo 0.66 ± 0.08 0.75 ± 0.08 0.003
 Change at 3 mo 0.02 ± 0.03 0.14 ± 0.08 < 0.001
TG (mmol/L)
 Baseline 3.29 ± 0.25 3.35 ± 0.41 0.64
 3 mo 3.12 ± 0.33 2.49 ± 0.42 < 0.001
 Change at 3 mo –0.17 ± 0.28 –0.86 ± 0.54 < 0.001
Non-HDL (mmol/L)
 Baseline 3.96 ± 0.23 4.01 ± 0.23 0.62
 3 mo 3.78 ± 0.32 3.46 ± 0.21 0.001
 Change at 3 mo –0.19 ± 0.17 0.54 ± 0.27 0.001

 

Variable Control group
MICT (n = 19)
Intervention group
Burst exercise (n = 21)
p value
Minutes of exercise achieved on the Bruce protocol
 Baseline 5.47 ± 1.65 5.60 ± 1.41 0.81
 3 mo 5.71 ± 1.96 6.87 ± 1.44 0.03
 Change at 3 mo 0.24 ± 1.39 1.27 ± 0.63 < 0.001
Self-reported min of exercise per mo 362 ± 109 460 ± 97 0.006
METS achieved on the Bruce protocol
 Baseline 5.35 ± 1.61 5.44 ± 1.37 0.81
 3 mo 5.54 ± 1.90 6.48 ± 1.36 < 0.001
 Change at 3 mo 0.19 ± 1.10 1.04 ± 0.52 < 0.001

 

Relative impacts of similar duration of sustained exercise vs burst exercise on biochemical parameters
Variable Control group
MICT (n = 7)
Intervention group
Burst exercise (n = 8)
p value
Self-reported exercise duration 380 ± 36 389 ± 34 0.64
 % change in HbA1C –3.7 ± 1.7 –7.9 ± 2.4 0.01
 % change in LDL –4.7 ± 3.4 –9.7 ± 3.8 0.008
 % change in HDL 3.7 ± 4.5 14.5 ± 7.5 0.001
 % change in TG –4.8 ± 5.3 –18.4 ± 5.6 0.001
Adverse Events Common Adverse Events: No hypoglycemic episodes occurred.
Serious Adverse Events: Not disclosed
Loss of participants due to adverse events: Not disclosed.
Study Author Conclusions Better outcomes were seen in with in HIIT group with regards to BMI, aerobic fitness, glucose metabolism, and lipid profiles.

Currently, HIIT modality is incorporated into the North American guidelines and European guidelines for patients with coronary artery disease and heart failure suggesting HIIT may provide better cardiovascular benefits compared to MICT. [2] Regarding study design and sample population, its randomized controlled design and similar baseline characteristics increase the internal validity of the study findings. However, due to the small sample size and being a single center study, the external validity may be limited. Included patients that were not on any glycemic medicines and did not have any cardiovascular disease at the time of study, which suggest that the observed outcomes may be largely attributable to the exercise programs rather than drugs or current cardiac conditions. Another limitation is that some of the outcomes were patient reported, which may be subjective and inaccurate. Finally, although three months may have been adequate to observe changes in HbA1c, long-term outcomes or long-term adherence to the work out protocols cannot be assumed. However, it is noted that those assigned to the burst HIIT groups tended to exercise for longer during a month compared to MICT group suggesting that individuals may find the novel regimen of short-duration, bust exercise protocols easier to maintain. Of note, despite the high-intensity exercise, no hypoglycemia was reported. In conclusion, it appears the novel high-intensity burst exercise protocols may provide superior outcomes in managing type II diabetes compared to moderate intensity continuous training. Further studies to evaluate the long-term adherence may be of an interest to determine whether this may be a feasible long-term lifestyle modification strategy.

 

References:

[1] Colberg SR, Sigal RJ, Fernhall B, et al. Exercise and type 2 diabetes: the American College of Sports Medicine and the American Diabetes Association: joint position statement. Diabetes Care. 2010;33(12):e147-67.
[2]. Pandey A, Suskin N, Poirier P. The impact of burst exercise on cardiometabolic status of patients newly diagnosed with type 2 diabetes. Can J Cardiol. 2017;33(12):1645-1651.

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