# Anti-Inflammatory and Antioxidant Effects of HIIT in Individuals with Long COVID: Insights into the Potential Role of Triphala

PMID: 40943540
Journal: International journal of molecular sciences
Published: 2025 Sep 4
Authors: Padkao T, Intakhiao S, Prakobkaew N, Buddhisa S, Teethaisong Y, Boonla O, Prasertsri P

## Question

Does supervised HIIT, alone or combined with Triphala supplementation, reduce inflammatory and oxidative-stress biomarkers in adults with long COVID?

## Summary

In screened adults with long COVID symptoms, 8 weeks of supervised cycling HIIT with or without Triphala was associated with within-group reductions in inflammatory and oxidative-stress biomarkers, but between-group interactions were not significant. Minor symptoms occurred in a few HIIT participants and no serious adverse events were reported.

## Population

- Adults with prior COVID-19 and persistent long COVID symptoms/post-exertional malaise symptoms.
- Sample size: 104
- Age: 22.41 +/- 6.85 years
- Sex: 28 men and 76 women
- Fitness level: Inactive; regular physical activity >=2 sessions/week or >=150 min/week was excluded.
- Health status: Active infection-free adults with long COVID symptoms and BMI 18.5-24.9 kg/m2; many cardiometabolic and inflammatory conditions were excluded.

## Methodology

- Randomized controlled trial with control/placebo, HIIT, and HIIT plus Triphala groups
- 8 weeks
- Supervised physiotherapy research laboratory
- Randomized and controlled study design.

## Protocol

- Supervised cycling HIIT.
- Modality: Stationary cycling.
- Work intervals: 4 min at 85% HRpeak.
- Recovery: 3 min active recovery at 60% HRpeak.
- Sets or repetitions: 4 intervals.
- Intensity: 85% HRpeak work, 60% HRpeak recovery, 50-60 rpm.
- Session duration: About 38 min including 5 min warm-up and 5 min cool-down.
- Frequency: 3 sessions/week.
- Program length: 8 weeks.
- Progression: Individualized load adjustments to maintain HR targets.
- Control/placebo.
- Modality: No structured exercise.
- Program length: 8 weeks.

## Outcomes

### Inflammation
Status: mixed
HIIT arms had within-group IFN-gamma and TNF-alpha reductions, but interactions were nonsignificant.

IFN interactions p=0.837; TNF interactions p=0.175.

### Oxidative stress
Status: mixed
MDA and protein carbonyls decreased within exercise groups, but between-group interactions were nonsignificant.

MDA interaction p=0.710; protein carbonyl interaction p=0.968.

### Safety
Status: mixed
No serious adverse events or ALT/creatinine changes; four minor symptom events occurred.

ALT p=0.315; creatinine p=0.249; minor events in 4 participants (5.97%).

## Practical Insights

- A clinical 4 x 4 cycling format can be monitored with HRpeak, RPE, dyspnea, and symptom checks.
- For long COVID, absence of serious events in a screened lab sample does not establish safety for unsupervised use.
- Between-group nonsignificance should temper biomarker benefit claims.

## Limitations

- Young highly screened long-COVID sample
- Nonsignificant group-by-time interactions
- No PESE/PEM diary
- No Triphala-only group
- Limited biomarker panel
- Variable compliance
- Clinical supervision limits generalizability

## Safety And Adherence

- No serious adverse events were reported.
- Four participants (5.97%) experienced minor events in the final week during the fourth HIIT cycle: leg muscle fatigue, dizziness, and transient hypotension; none discontinued.
- The protocol was supervised by licensed physical therapists with continuous adverse-event monitoring, but post-exertional symptom exacerbation within 24 h was not measured.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/40943540/) (pubmed)
- [DOI](https://doi.org/10.3390/ijms26178623) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12428976/) (full text)

## Agent Guidance

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