A pilot study of high-intensity interval training and continuous positive airway pressure on vascular health in Thai adults with obesity, obstructive sleep apnea, and type 2 diabetes
Question
How do 12 weeks of HIIT and CPAP compare with usual care for vascular health, sleep indices, biomarkers, and body composition in adults with obesity, OSA, and T2DM?
Summary
In a small Thai pilot study of adults with obesity, moderate-to-severe sleep apnea, and type 2 diabetes, 12 weeks of supervised treadmill HIIT improved vascular markers from baseline and reduced apnea severity and BMI compared with usual care. CPAP reduced apnea severity and improved oxygen saturation but did not improve vascular outcomes.
Methodology
- Thai adults with obesity, moderate-to-severe obstructive sleep apnea, and type 2 diabetes
- 28 participants.
- Treadmill walking or running.
- Work intervals: 4 minutes.
- Recovery: 3 minutes active recovery.
- Intensity: 85-95% estimated HRmax during intervals; 50-60% HRmax recovery.
- About 38 minutes plus cool-down duration not precisely quantified.
- 3 non-consecutive days per week.
- 12 weeks after familiarization.
- Pilot assessor-blinded quasi-experimental study with age-matched sequential assignment
- FMD, CIMT, AHI, and BMI were tracked.
Outcomes
CIMT
HIIT improved CIMT compared with control and from baseline.
Group x time P = 0.02; HIIT vs control post-hoc P = 0.05; HIIT within-group mean difference -0.10 mm, 95% CI -0.15 to -0.05
FMD
FMD improved from baseline in the HIIT group, but between-group post-hoc differences were not significant.
Group x time P = 0.05; HIIT within-group mean difference 3.52%, 95% CI 1.31 to 5.74
AHI
Both HIIT and CPAP reduced apnea-hypopnea index compared with control and from baseline.
Group x time P < 0.01; HIIT before 17.2 +/- 1.5 to 10.2 +/- 3.6 events/h; CPAP 17.2 +/- 1.4 to 12.1 +/- 3.8
Oxygenation
Only CPAP significantly improved mean oxygen saturation and oxygen saturation nadir compared with control.
Mean SpO2 and nadir group x time P < 0.01; CPAP within-group mean SpO2 +2.61%, nadir +8.60%
Biomarkers
No significant interactions were observed for lipids, fasting blood sugar, or HbA1c.
Remaining blood biomarkers p > 0.05 for interactions
Insights
- A clinically supervised 4 x 4-minute treadmill protocol was feasible with high adherence in a high-risk cardiometabolic population.
- Familiarization and conservative workload progression were built into the protocol before the main 85-95% HRmax program.
- The quasi-experimental pilot design means results should guide hypothesis generation, not firm efficacy claims.
Limitations
- Small pilot sample.
- Quasi-experimental sequential assignment, not randomized.
- Single-center setting.
- Estimated HRmax rather than CPET-based prescription.
- Treadmill speed and incline were not systematically recorded.
- Self-reported food logs may bias dietary control.
- Longer follow-up was not conducted.
Safety
- All HIIT participants reported transient thigh/calf soreness during familiarization that resolved within 7-9 days.
- No significant musculoskeletal issues or adverse events occurred during the intervention period.
- Exercise termination criteria were prespecified for abnormal symptoms and blood pressure responses.