High-Intensity Interval Exercise for Insulin Sensitivity

Overseen By Jenna Gillen, PhD

Age: 18 - 65

Sex: Any

Trial Phase: Academic

Sponsor: University of Toronto

Must not be taking: Blood glucose, Lipid metabolism, Corticosteroids, nSAIDs

Disqualifiers: Cardiovascular, Metabolic, PCOS, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 3

24 Participants Needed

Trial Summary

Do I have to stop taking my current medications for the trial?

Yes, you must stop taking medications for managing blood glucose or lipid metabolism, oral contraceptives, and medications affecting substrate metabolism like corticosteroids or nSAIDs.

What data supports the idea that High-Intensity Interval Exercise for Insulin Sensitivity is an effective treatment?

The available research shows that High-Intensity Interval Exercise (HIIT) is effective in improving insulin sensitivity. One study found that after 12 weeks, both HIIT and Sprint Interval Training (SIT) improved insulin sensitivity by about 26% and 39%, respectively, while moderate-intensity continuous training (MICT) did not show any improvement. Another study highlighted that HIIT and SIT can improve glycemic control, which is important for managing conditions like type 2 diabetes, in less time compared to traditional aerobic exercise. This makes HIIT a time-efficient and effective treatment for improving insulin sensitivity. ^{1 2 3 4 5}

What safety data exists for high-intensity interval exercise?

High-intensity interval exercise (HIIE) has been studied for safety in various populations, including those with cardiovascular and metabolic diseases, older adults, and patients with cardiovascular disease. A systematic review found that HIIE can have a higher rate of adverse responses (~8%) in patients with cardiometabolic diseases compared to moderate-intensity exercise, suggesting the need for caution and supervision. In older adults, HIIT was generally well-tolerated, though more research is needed. For patients with cardiovascular disease, HIIT showed a low rate of major adverse cardiovascular events when applied in cardiac rehabilitation settings, with one major event per 17,083 training sessions. Overall, while HIIE can be safe, it requires careful monitoring, especially in clinical populations. ^{1 6 7 8 9}

Is high-intensity interval exercise a promising treatment for improving insulin sensitivity?

Yes, high-intensity interval exercise (HIIT) is a promising treatment for improving insulin sensitivity. Studies show that HIIT can improve insulin sensitivity significantly, often more effectively than traditional continuous exercise, and it requires less time commitment. ^{1 3 4 10 11}

What is the purpose of this trial?

High-intensity interval exercise (HIIE) is a type of exercise that involves alternating periods of intense exercise with periods of rest. HIIE has been shown to improve many aspects of cardiovascular and metabolic health in a time-efficient manner (e.g., only 20 minutes per exercise session). An important health benefit of exercise is improved blood sugar control, which can help reduce the risk of metabolic diseases like type 2 diabetes. A single session of HIIE has been shown to improve blood sugar in males, but it is unknown if females achieve the same health benefit. It is also not fully understood how exercise improves blood sugar in males and females. Therefore, the purpose of this project is 1) to determine if a single session of HIIE improves blood sugar control in males and females, and 2) to evaluate if changes in skeletal muscle can explain the beneficial effects of HIIE on blood sugar.

Research Team

Stephanie Estafanos, MSc

Principal Investigator

University of Toronto

Eligibility Criteria

This trial is for healthy, non-smoking men and women aged 18-35 with a BMI of 18-27 who are moderately active but not training for sports. Women must have regular menstrual cycles and can't be using oral contraceptives or be pregnant. Participants should not have metabolic diseases, be on blood glucose medications, or follow low-carb diets.

Inclusion Criteria

Your weight has stayed about the same (within 4.4 pounds) for the past 6 months.

You do exercise one to three times a week, and you are not training for a specific sport.

My menstrual cycles are regular, lasting 21 to 35 days.

Exclusion Criteria

I have been diagnosed with a heart, metabolic disease, hormone imbalance, or PCOS.

I am currently pregnant, breastfeeding, or going through menopause.

I am currently taking corticosteroids or NSAIDs.

Timeline

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Baseline Measurement

Participants' insulin sensitivity and muscle outcomes are measured following 30 minutes of sitting in the lab

1 day

1 visit (in-person)

Exercise Intervention

Participants undergo a single session of high-intensity interval exercise (HIIE) on a stationary bike

1 day

1 visit (in-person)

Post-exercise Measurement

Insulin sensitivity and muscle outcomes are measured after the exercise session

3 hours

1 visit (in-person)

Follow-up

Participants are monitored for safety and effectiveness after the exercise intervention

4 weeks

Treatment Details

Interventions

• High-intensity interval exercise

Trial Overview The study aims to see if one session of high-intensity interval exercise (HIIE) improves blood sugar control in both males and females compared to just resting. It also investigates how HIIE affects muscle metabolism related to blood sugar improvements.

Participant Groups

Group I: Males Experimental Treatment 2 Interventions

Male participant group

Group II: Females Experimental Treatment 2 Interventions

Female participant group

Who Is Running the Clinical Trial?

University of Toronto

Lead Sponsor

Trials

739

Recruited

1,125,000+

Findings from Research

In a study of 42 overweight women, all three training methods (SIT, HIIT, and MICT) improved cardiorespiratory fitness (V̇O2peak) and reduced body mass by about 25% and 5%, respectively, over 12 weeks.

SIT and HIIT significantly enhanced insulin sensitivity, with improvements of approximately 26% and 39%, while MICT did not affect insulin sensitivity but did lower fasting glucose levels.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Twelve weeks of low volume sprint interval training improves cardio-metabolic health outcomes in overweight females. Sun, S., Zhang, H., Kong, Z., et al.[2019]

A 12-week study involving 15 participants with type 2 diabetes showed that high intensity interval exercise (HI-IE) is as feasible as moderate intensity continuous exercise (MI-CE), with both groups maintaining high adherence rates of over 97%.

Both HI-IE and MI-CE effectively reduced total body fat and trunk fat, but neither intervention significantly changed glycated hemoglobin A1c (HbA1c) levels, indicating limited impact on blood sugar control in participants who were already well-managed.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Feasibility and preliminary efficacy of high intensity interval training in type 2 diabetes. Terada, T., Friesen, A., Chahal, BS., et al.[2022]

Sprint interval training (SIT) significantly improved insulin sensitivity and cardiovascular fitness in sedentary men, achieving similar results to traditional moderate-intensity continuous training (MICT) after 12 weeks, despite requiring only a fraction of the time (10 minutes vs. 50 minutes per session).

Both SIT and MICT led to a 19% increase in peak oxygen uptake and similar enhancements in skeletal muscle mitochondrial content, indicating that brief, intense exercise can be as effective as longer, moderate exercise for improving cardiometabolic health.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Twelve Weeks of Sprint Interval Training Improves Indices of Cardiometabolic Health Similar to Traditional Endurance Training despite a Five-Fold Lower Exercise Volume and Time Commitment. Gillen, JB., Martin, BJ., MacInnis, MJ., et al.[2022]

A single session of reduced-exertion high-intensity interval training (REHIT) led to significant physiological changes, including decreased muscle glycogen and increased activation of key metabolic pathways, suggesting it effectively stimulates muscle adaptation similar to traditional aerobic exercise.

REHIT resulted in more pronounced changes in oxygen consumption and metabolic markers compared to moderate aerobic exercise, indicating its potential as a time-efficient alternative for improving fitness and metabolic health.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Physiological and molecular responses to an acute bout of reduced-exertion high-intensity interval training (REHIT). Metcalfe, RS., Koumanov, F., Ruffino, JS., et al.[2022]

High-intensity interval training (HIIT) and sprint interval training (SIT) can significantly improve glycemic control in individuals with metabolic syndrome (MetS) and type 2 diabetes (T2D), potentially more effectively than traditional aerobic exercise.

These interval training methods require less time commitment, addressing common barriers to regular exercise, making them a practical option for enhancing glucose metabolism in patients with MetS and T2D.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Impact of high-intensity interval training and sprint interval training on peripheral markers of glycemic control in metabolic syndrome and type 2 diabetes. Jiménez-Maldonado, A., García-Suárez, PC., Rentería, I., et al.[2022]

A systematic review of 11 studies involving 156 clinically stable patients with cardiometabolic diseases found that high-intensity interval exercise (HIIE) can lead to adverse responses in about 8% of individuals, indicating a higher risk compared to moderate-intensity exercise.

It is recommended that patients with cardiometabolic diseases who wish to engage in HIIE should be clinically stable, have prior experience with moderate-intensity exercise, and exercise under supervision to ensure safety.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

What Doesn't Kill You Makes You Fitter: A Systematic Review of High-Intensity Interval Exercise for Patients with Cardiovascular and Metabolic Diseases. Levinger, I., Shaw, CS., Stepto, NK., et al.[2022]

A scoping review of 69 studies on high-intensity interval training (HIIT) in older adults found that HIIT protocols are generally well-tolerated and can provide significant health benefits, particularly in improving cardiorespiratory fitness.

Most research has focused on healthy older adults, highlighting a need for larger studies and more investigation into HIIT's effects on older adults with various health conditions.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

High-Intensity Interval Training in Older Adults: a Scoping Review. Marriott, CFS., Petrella, AFM., Marriott, ECS., et al.[2021]

High-intensity interval training (HIIT) is as effective, if not more so, than traditional moderate-intensity continuous training (MICT) for patients with cardiovascular disease, based on a systematic review of 23 studies involving 1117 participants.

The safety profile of HIIT in cardiac rehabilitation is promising, with only one major cardiovascular adverse event reported per 17,083 training sessions, indicating that HIIT can be safely implemented in this population.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

High-Intensity Interval Training for Patients With Cardiovascular Disease-Is It Safe? A Systematic Review. Wewege, MA., Ahn, D., Yu, J., et al.[2021]

High-intensity interval exercise (HIIE) significantly improves glucose tolerance and insulin sensitivity in adolescent boys, showing a greater reduction in plasma glucose and insulin levels compared to a control group after exercise.

Both HIIE and moderate-intensity exercise (MIE) were equally enjoyable for participants, suggesting that HIIE can be a time-efficient and effective alternative to MIE for health benefits without sacrificing enjoyment.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

High intensity interval exercise is an effective alternative to moderate intensity exercise for improving glucose tolerance and insulin sensitivity in adolescent boys. Cockcroft, EJ., Williams, CA., Tomlinson, OW., et al.[2016]

A 6-week reduced-exertion high-intensity interval training (REHIT) program significantly improved insulin sensitivity by 28% in sedentary young men, demonstrating its potential for enhancing metabolic health.

Both male and female participants showed increased aerobic capacity, with improvements of 15% and 12% respectively, suggesting that REHIT is an effective and time-efficient alternative to traditional exercise for improving fitness and reducing diabetes risk.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Towards the minimal amount of exercise for improving metabolic health: beneficial effects of reduced-exertion high-intensity interval training. Metcalfe, RS., Babraj, JA., Fawkner, SG., et al.[2022]

Sprint interval exercise (SIE) significantly improves insulin sensitivity more than continuous exercise (CELOW and CEHIGH) in young, healthy men, with the greatest effect observed 30 minutes post-exercise.

The improvement in insulin sensitivity after SIE may be due to increased post-exercise hyperinsulinemia and reduced lipolysis, indicating a unique mechanism of action compared to continuous exercise.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Higher insulin-sensitizing response after sprint interval compared to continuous exercise. Ortega, JF., Fernández-Elías, VE., Hamouti, N., et al.[2015]

References

1. England pubmed.ncbi.nlm.nih.gov

Twelve weeks of low volume sprint interval training improves cardio-metabolic health outcomes in overweight females. [2019]

2. Ireland pubmed.ncbi.nlm.nih.gov

Feasibility and preliminary efficacy of high intensity interval training in type 2 diabetes. [2022]

3. United States pubmed.ncbi.nlm.nih.gov

Twelve Weeks of Sprint Interval Training Improves Indices of Cardiometabolic Health Similar to Traditional Endurance Training despite a Five-Fold Lower Exercise Volume and Time Commitment. [2022]

4. Germany pubmed.ncbi.nlm.nih.gov

Physiological and molecular responses to an acute bout of reduced-exertion high-intensity interval training (REHIT). [2022]

5. Netherlands pubmed.ncbi.nlm.nih.gov

Impact of high-intensity interval training and sprint interval training on peripheral markers of glycemic control in metabolic syndrome and type 2 diabetes. [2022]

6. United States pubmed.ncbi.nlm.nih.gov

What Doesn't Kill You Makes You Fitter: A Systematic Review of High-Intensity Interval Exercise for Patients with Cardiovascular and Metabolic Diseases. [2022]

7. Switzerland pubmed.ncbi.nlm.nih.gov

High-Intensity Interval Training in Older Adults: a Scoping Review. [2021]

8. England pubmed.ncbi.nlm.nih.gov

High-Intensity Interval Training for Patients With Cardiovascular Disease-Is It Safe? A Systematic Review. [2021]

9. Australia pubmed.ncbi.nlm.nih.gov

High intensity interval exercise is an effective alternative to moderate intensity exercise for improving glucose tolerance and insulin sensitivity in adolescent boys. [2016]

10. Germany pubmed.ncbi.nlm.nih.gov

Towards the minimal amount of exercise for improving metabolic health: beneficial effects of reduced-exertion high-intensity interval training. [2022]

11. Germany pubmed.ncbi.nlm.nih.gov

Higher insulin-sensitizing response after sprint interval compared to continuous exercise. [2015]