From the Guidelines
High-intensity interval training (HIIT) has been shown to reduce A1C and BMI, and improve fitness levels in individuals with type 2 diabetes, making it a beneficial form of exercise for this population. According to the most recent and highest quality study, HIIT involves short bursts of aerobic training performed between 65% and 90% VO2peak or 75% and 95% heart rate peak for 10 s to 4 min with 12 s to 5 min of active or passive recovery 1.
Key Benefits of HIIT
- Reduces A1C and BMI in individuals with type 2 diabetes
- Improves fitness levels in individuals with type 2 diabetes
- Can lead to transient increases in post-exercise hyperglycemia, requiring careful monitoring of blood glucose
- May require bolus correction for individuals with type 1 diabetes
Implementing HIIT
To implement HIIT, individuals can start with 2-3 sessions per week, allowing for at least 24-48 hours of recovery between sessions. Each session can last 20-30 minutes, including warm-up and cool-down, with high-intensity intervals lasting 15-60 seconds at 80-95% of maximum heart rate, followed by 1-3 minutes of lower-intensity recovery periods. For example:
- Warm up for 5 minutes
- Perform 8-10 rounds of 30 seconds high-intensity work followed by 90 seconds of recovery
- Cool down for 5 minutes
Important Considerations
- Individuals with type 1 diabetes may need to use bolus correction and monitor blood glucose closely when starting HIIT
- Individuals with type 2 diabetes should monitor blood glucose when starting HIIT
- Proper recovery is crucial to avoid overtraining and reduce injury risk
- As individuals become more conditioned, they can gradually increase the frequency of HIIT sessions to 4 times per week, but should always listen to their body and adjust as needed 1.
From the Research
Effects of High-Intensity Interval Training (HIIT)
- HIIT has been shown to be safe and effective in improving exercise tolerance in patients with heart disease and very high cardiovascular risk 2.
- Compared to moderate-intensity continuous training (MICT), HIIT has similar or better effects on increasing peak oxygen consumption (VO2max) in middle-aged and older women 3.
- HIIT has been found to generate adaptations in VO2max-ES and diastolic blood pressure after exercise, with additional positive effects on systolic blood pressure after exercise compared to MICT 3.
- In adults with obesity, moderate-intensity interval training (MIIT) may be more tolerable than HIIT, with fewer immune system perturbations and less muscle pain 4.
- Locomotor HIIT is a promising new strategy for recovering walking capacity post-stroke, with potential benefits over moderate-intensity aerobic training 5.
- A systematic review and meta-analysis found that HIIT was generally more effective than MICT at improving peak oxygen consumption (Vo2peak) in patients with heart failure, with varying effect sizes depending on the HF subtype and HIIT protocol used 6.
Comparison of HIIT and MICT
- Studies have compared the effects of HIIT and MICT on various outcomes, including exercise tolerance, VO2max, and blood pressure 2, 3, 6.
- The results suggest that HIIT may be more effective than MICT in improving certain outcomes, such as VO2max and exercise tolerance, but may also be associated with greater increases in blood lactate and perceived exertion 3, 4.
Considerations for HIIT Protocols
- The optimal HIIT protocol for different populations and outcomes is not yet clear, and further research is needed to determine the most effective and safe protocols 5, 6.
- Factors such as interval duration, intensity, and volume may influence the effectiveness of HIIT, and individualized protocols may be necessary to achieve optimal outcomes 6.