# Short-term HIIT impacts HDL function differently in lean, obese, and diabetic subjects

PMID: 39234305
Journal: Frontiers in physiology
Published: 2024
Authors: Zhu L, An J, Luu T, Reyna SM, Tantiwong P, Sriwijitkamol A, Musi N, Stafford JM

## Question

How does a short-term supervised HIIT program affect HDL function and lipoprotein measures in lean, obese, and type 2 diabetic adults?

## Summary

This secondary analysis used stored samples from six lean, six obese, and six recently diagnosed type 2 diabetes participants after a supervised 15-day cycling HIIT program. HIIT improved HDL antioxidant capacity in all groups, improved cholesterol efflux and HDL-C only in lean participants, and improved several lipid markers mainly in obese and diabetic participants.

## Population

- Six lean, six obese nondiabetic, and six obese type 2 diabetic sedentary participants from a prior intervention.
- Sample size: 18
- Fitness level: Sedentary
- Health status: Lean, obese, and recently diagnosed T2DM groups

## Methodology

- Secondary biochemical analysis of a supervised short-term exercise intervention
- 15 days
- Clinical exercise/laboratory setting

## Protocol

- 15-day alternative cycling HIIT.
- Modality: Cycle ergometer.
- Work intervals: 2 minutes at 90% VO2peak.
- Recovery: 8 minutes at 70% VO2peak within each set; 2 minutes complete rest after each set.
- Sets or repetitions: Four 10-minute periods.
- Intensity: 70% and 90% VO2peak.
- Session duration: 40 minutes exercise plus rests.
- Frequency: Daily during 15-day program; exact weekly schedule not otherwise reported.
- Program length: 15 days.
- Progression: Not reported.

## Outcomes

### HDL antioxidant
Status: improved
HDL antioxidant capacity improved in lean, obese, and T2DM groups.

Post-HIIT HDL delayed LDL oxidation in all groups; copper reduction improved in lean and T2DM.

### Cholesterol efflux
Status: mixed
Cholesterol efflux improved only in lean subjects.

Figure 4D; group-specific significant improvement only in lean.

### Lipid profile
Status: mixed
TG improved in obese and T2DM; LDL-C and VLDL-C changes were strongest in T2DM; HDL-C increased only in lean.

T2DM TG/HDL-C decreased from 3.995 +/- 0.486 to 2.512 +/- 0.218, p<0.001.

## Practical Insights

- Metabolic state can change which lipid or HDL function markers respond to HIIT.
- Do not equate HDL antioxidant improvements with broad HDL-C increases or clinical cardiovascular outcomes.

## Limitations

- Six samples per group.
- Secondary analysis of stored samples.
- No non-exercise control.
- Surrogate lab HDL function outcomes.
- Limited plasma prevented some HDL anti-inflammatory assays.

## Safety And Adherence

- No adverse events were reported in the reviewed article text.
- The study used supervised training and clinical sampling; because participants included obese and recently diagnosed T2DM groups, translation requires medical screening and medication-aware supervision.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/39234305/) (pubmed)
- [DOI](https://doi.org/10.3389/fphys.2024.1423989) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11371628/) (full text)

## Agent Guidance

Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.