# Efficacy of high-intensity interval training versus continuous training on serum myonectin and lipid outcomes in adults with metabolic syndrome: A post-hoc analysis of a clinical trial

PMID: 39024345
Journal: PLOS ONE
Published: 2024
Authors: Petro JL, Fragozo-Ramos MC, Milán AF, Aristizabal JC, Calderón JC, Gallo-Villegas J

## Question

Is supervised HIIT more effective than moderate continuous training for serum myonectin and lipid-related outcomes in adults with metabolic syndrome?

## Summary

In adults with metabolic syndrome, 12 weeks of supervised treadmill HIIT was not superior to moderate continuous training for myonectin, lipid profile, free fatty acids, or intramuscular lipids. HIIT showed a small within-group increase in myonectin, but the study was a post-hoc analysis and several outcomes were exploratory.

## Population

- Adults aged 40-60 with metabolic syndrome.
- Sample size: 60
- Age: 50.8 +/- 6.0 years
- Sex: 70% female
- Fitness level: Clinical metabolic syndrome sample
- Health status: Metabolic syndrome, mostly overweight/obese with dyslipidemia

## Methodology

- Post-hoc analysis of a randomized clinical trial
- 12 weeks
- Supervised treadmill training in a cardiac rehabilitation/physiotherapy setting
- Randomized and controlled study design.

## Protocol

- Treadmill HIIT.
- Modality: Treadmill.
- Work intervals: 1 minute.
- Recovery: 2 minutes at 50% VO2peak.
- Sets or repetitions: 6 intervals.
- Intensity: 90% VO2peak.
- Session duration: 22 minutes including warm-up and cooldown.
- Frequency: 3 sessions/week.
- Program length: 12 weeks.
- Progression: No clear progression described.
- MICT.
- Modality: Treadmill.
- Work intervals: Continuous.
- Sets or repetitions: 30 minutes continuous.
- Intensity: 60% VO2peak.
- Session duration: 36 minutes including warm-up and cooldown.
- Frequency: 3 sessions/week.
- Program length: 12 weeks.
- Progression: No clear progression described.

## Outcomes

### Myonectin
Status: mixed
HIIT was not superior to MICT, but HIIT showed a small within-group myonectin increase by robust estimation.

Between-group p=.661; HIIT robust within-group p=.042; paired t p=.055.

### Lipids
Status: no clear change
Lipid profile and free fatty acids did not significantly change in either group.

Between-group lipid and FFA p values were all >.05.

### Intramuscular lipids
Status: no clear change
IMCL, EMCL, and total intramuscular lipid did not significantly change in either group.

HIIT IMCL p=.893, EMCL p=.401, total p=.715; MICT IMCL p=.401, EMCL p=.929, total p=.735.

### Body composition
Status: mixed
Both groups showed favorable body-composition signals, but between-group differences were not significant.

AFMI between-group p=.713; ALM p=.810.

## Practical Insights

- HIIT was shorter than MICT but did not produce superior lipid biomarker changes.
- Biomarker-focused claims require larger primary trials.
- Metabolic syndrome protocols should not be translated without clinical screening.

## Limitations

- Post-hoc analysis.
- Possible type II error.
- Small intramuscular lipid subsample.
- Statin imbalance between groups.
- Longer than 12 weeks may be needed for lipid outcomes.
- Morning timing may have affected lipid results.

## Safety And Adherence

- The article referred to the parent trial as reporting both interventions safe.
- No article-specific adverse events were reported.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/39024345/) (pubmed)
- [DOI](https://doi.org/10.1371/journal.pone.0307256) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11257237/) (full text)

## Agent Guidance

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