# Serum Metabolome Adaptations Following 12 Weeks of High-Intensity Interval Training or Moderate-Intensity Continuous Training in Obese Older Adults

PMID: 36837817
Journal: Metabolites
Published: 2023 Jan 29
Authors: Youssef L, Bourgin M, Durand S, Aprahamian F, Lefevre D, Maiuri MC, Marcangeli V, Dulac M, Hajj-Boutros G, Buckinx F, Peyrusqué E, Gaudreau P, Morais JA, Gouspillou G, Kroemer G, Aubertin-Leheudre M, Noirez P

## Question

How do 12 weeks of supervised HIIT versus MICT alter the serum metabolome in obese older adults, and how are these metabolite changes associated with clinical and biological adaptations?

## Summary

This sub-analysis of two randomized exercise trials compared serum metabolome changes after 12 weeks of supervised elliptical HIIT or treadmill moderate continuous training in obese older adults. Both programs changed serum metabolites, with 21 metabolites changing after HIIT and 18 after MICT, but the paper mainly reports metabolite associations rather than direct clinical superiority. A HIIT-related metabolite change correlated with handgrip strength, while other metabolites correlated with insulin-sensitivity and lipid markers.

## Population

- Thirty-eight obese older adults with complete pre/post metabolomics, assigned to HIIT or MICT.
- Sample size: 38
- Age: HIIT 67.73 +/- 3.87 years; MICT 70.41 +/- 3.89 years
- Sex: 21 men and 17 women overall; HIIT 13/13 men/women, MICT 8/4
- Health status: Moderately obese older adults; baseline BMI about 30 kg/m2.

## Methodology

- Sub-analysis combining participants from prior randomized controlled trials, with pre/post serum metabolomics after supervised HIIT or MICT.
- 12 weeks, 3 supervised sessions per week.
- Supervised exercise intervention in the Montreal area with trained kinesiologists; metabolomics performed from fasting serum.
- Randomized and controlled study design.

## Protocol

- Elliptical HIIT.
- Modality: Elliptical trainer.
- Work intervals: 30-second high-intensity sprints.
- Recovery: 90 seconds at moderate intensity.
- Sets or repetitions: Repeated intervals for 20 minutes.
- Intensity: 80-85% maximal heart rate or Borg RPE >17 during hard intervals.
- Session duration: 30 minutes including 5-minute warm-up and 5-minute cool-down.
- Frequency: 3 sessions per week.
- Program length: 12 weeks.
- Progression: Continuous speed/resistance adjustment to maintain intensity.
- MICT.
- Modality: Treadmill walking.
- Intensity: 60-70% maximal heart rate or Borg 13-14.
- Session duration: 60 minutes.
- Frequency: 3 sessions per week.
- Program length: 12 weeks.
- Progression: Treadmill speed/resistance adjusted to maintain target intensity.

## Outcomes

### Serum metabolome
Status: mixed
Fifty-one metabolites changed after the overall 12-week intervention; 21 changed after HIIT and 18 after MICT.

Significance threshold p < 0.05 with additional FDR analyses reported.

### PCae (22:1) and strength
Status: improved
In the HIIT group, PCae (22:1) change correlated positively with handgrip strength change.

r = 0.52, p < 0.01.

### 2-oxoglutaric acid and insulin sensitivity
Status: mixed
2-oxoglutaric acid change correlated with better insulin-sensitivity markers.

HOMA-IR across both groups r = -0.44, p < 0.01; QUICKI across both groups r = 0.46, p < 0.01 and HIIT r = 0.51, p < 0.01.

### Fumaric acid and acetylcarnitine lipid correlations
Status: mixed
In MICT, fumaric acid correlated positively with triglycerides and acetylcarnitine correlated positively with LDL cholesterol.

Fumaric acid/TG r = 0.73, p < 0.01; acetylcarnitine/LDL r = 0.81, p < 0.01.

## Practical Insights

- For older adults with obesity, low-impact supervised HIIT can be structured with short 30-second efforts and longer moderate recoveries.
- This paper is stronger for mechanistic context than for direct workout recommendations.
- RPE-based intensity targets may be useful when medications make heart-rate targets less reliable.

## Limitations

- Small unequal groups.
- Sub-analysis of participants with available serum samples.
- Volunteer sample with possible selection bias.
- Different devices for HIIT and MICT.
- Serum metabolome may not represent whole-body metabolism.
- Replication in an independent cohort is needed.

## Safety And Adherence

- No adverse events were reported in this metabolomics article.
- The HIIT modality used an elliptical to reduce lower-limb joint impact.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/36837817/) (pubmed)
- [DOI](https://doi.org/10.3390/metabo13020198) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9967246/) (full text)

## Agent Guidance

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