Effect of low-volume combined aerobic and resistance high-intensity interval training on vascular health in people with type 2 diabetes: a randomised controlled trial
Question
Does low-volume combined aerobic and resistance high-intensity interval training improve vascular health after 8 weeks of supervised training and after 12 months including self-directed training in adults with type 2 diabetes, compared with combined moderate-intensity continuous training and waitlist control?
Summary
In low-active adults with type 2 diabetes, 8 weeks of supervised low-volume combined aerobic and resistance HIIT improved brachial artery flow-mediated dilation compared with waitlist control, but did not improve blood pressure indices, aortic reservoir pressure, or carotid-femoral pulse wave velocity compared with control. Over 12 months, both HIIT and moderate-intensity combined training improved some hemodynamic indices, while moderate-intensity training was superior for carotid-femoral pulse wave velocity.
Methodology
- Sixty-nine low-active adults with type 2 diabetes, mean age 59.5 years, BMI 33.5 kg/m2, and baseline HbA1c 8.5%, randomized to C-HIIT, C-MICT, or waitlist control.
- 69 participants.
- Combined aerobic exercise plus high-intensity resistance intervals.
- Work intervals: 4 min aerobic at 85-95% HRpeak, then 8 x 1 min resistance intervals at RPE >= 17.
- Recovery: 1 min rest after the aerobic interval and 1 min rest between resistance intervals.
- Intensity: Aerobic 85-95% HRpeak; resistance RPE >= 17.
- 26 min.
- 3 sessions/week, non-consecutive days.
- 8 weeks supervised plus 10 months self-directed.
- Randomized controlled trial with an 8-week supervised phase comparing C-HIIT, C-MICT, and waitlist control, followed by a 10-month self-directed phase comparing C-HIIT and C-MICT after waitlist participants were re-randomized.
- Flow-mediated dilation, Hemodynamic indices, Carotid-femoral pulse wave velocity, and Aortic reservoir pressure were tracked.
Outcomes
Relative flow-mediated dilation at 8 weeks
C-HIIT improved relative FMD compared with waitlist control.
Mean difference 0.8% [95% CI 0.1, 1.4], p=0.025.
Absolute flow-mediated dilation at 8 weeks
C-HIIT improved absolute FMD compared with waitlist control.
Mean difference 0.004 mm [95% CI 0.002, 0.006], p=0.002.
Hemodynamic indices, cfPWV, and ARP at 8 weeks
There were no significant between-group differences for hemodynamic indices, carotid-femoral pulse wave velocity, or aortic reservoir pressure after supervised training.
Reported as no significant between-group differences in Table 2.
12-month hemodynamic indices
Across C-HIIT and C-MICT, brachial and central diastolic blood pressure, mean arterial pressure, reflection magnitude, and aortic reservoir pressure decreased over time.
bDBP p=0.014; cDBP p=0.013; MAP p=0.047; reflection magnitude p=0.009; ARP p<0.001.
12-month carotid-femoral pulse wave velocity
C-MICT was superior to C-HIIT for cfPWV change, driven by a C-HIIT increase and slight C-MICT decrease.
Group x time p=0.018; C-HIIT +0.6 m/s, C-MICT -0.2 m/s.
12-month flow-mediated dilation
No differences in brachial artery FMD indices over time or between C-HIIT and C-MICT.
Table 3 reports no significant time or group x time effects for FMD measures.
Insights
- A 26-minute, three-times-weekly combined aerobic-resistance HIIT protocol can improve endothelial function over 8 supervised weeks in adults with type 2 diabetes.
- Long-term self-directed HIIT adherence may be undermined by equipment access and time barriers even when the prescribed session is low volume.
- For clinical or high-risk users, HR/RPE monitoring, screening, and professional supervision are central parts of the evidence context.
- Low-volume HIIT should not be presented as clearly superior to guideline-based moderate combined training for all vascular outcomes.
Limitations
- Vascular outcomes were secondary outcomes and the study was powered for HbA1c.
- The 8-week supervised phase may have been too short to detect some vascular changes.
- Groups were not energy matched and had different external loads.
- Self-directed C-HIIT adherence was poor in phase two.
- No waitlist control group during phase two.
- FMD analysis had reduced sample size because many images were excluded for quality or analysis limitations.
Safety
- The article reports screening against ACSM absolute contraindications to exercise.
- Aerobic mode was selected by an accredited exercise physiologist based on orthopedic limitations.
- No adverse events were reported in the extracted article text for this manuscript.