# Acute-Phase Inflammatory Response to Single-Bout HIIT and Endurance Training: A Comparative Study

PMID: 27212809
Journal: Mediators of Inflammation
Published: 2016
Authors: Kaspar F, Jelinek HF, Perkins S, Al-Aubaidy HA, deJong B, Butkowski E

## Question

Do acute inflammatory and metabolic blood-marker responses differ after a single low-volume HIIT cycling session compared with a traditional endurance cycling session in healthy untrained adults?

## Summary

In seven healthy untrained young adults who completed both exercise sessions, a single sprint-style HIIT cycling session produced broadly similar short-term inflammatory blood-marker responses to a 45-minute endurance cycling session. The endurance session lowered the IL-6/IL-10 ratio at 30 minutes and MCP-1 two days later, while individual cytokines and CRP did not significantly change after either session.

## Population

- Healthy untrained young adults without chronic disease, medication or supplement use, smoking, or regular structured training
- Sample size: 7
- Age: 18 to 30 years
- Sex: Not reported in extractable full text
- Fitness level: Untrained; not undertaking high- or moderate-intensity training more than once per week
- Health status: Healthy, nonsmoking adults with BMI 18 to 30 kg/m2 and resting blood pressure between 90/60 and 140/90 mmHg

## Methodology

- Randomized-order repeated-measures acute exercise study
- Two single-session exercise visits separated by at least 7 days, with blood sampling before, 30 minutes after, and 2 days after each session
- University exercise laboratory
- Randomized and controlled study design.

## Protocol

- Sprint interval cycling.
- Modality: cycle.
- Work intervals: 30 seconds.
- Recovery: 240 seconds.
- Sets or repetitions: After a 2-minute warm-up below 50 W, participants completed six 30-second all-out supramaximal cycling bouts on an air-braked ergometer, with 4-minute low-load or passive recovery periods between bouts.
- Intensity: All-out supramaximal work bouts.
- Session duration: About 25 minutes.
- Frequency: Single session.
- Program length: Two single-session exercise visits separated by at least 7 days, with blood sampling before, 30 minutes after, and 2 days after each session.
- Progression: None.
- Endurance cycling.
- Modality: cycle.
- Sets or repetitions: Participants cycled for 45 minutes at 62.5% of age-predicted maximal heart rate.
- Intensity: 62.5% maximal heart rate.
- Session duration: 45 minutes.
- Frequency: Single session.
- Program length: Two single-session exercise visits separated by at least 7 days, with blood sampling before, 30 minutes after, and 2 days after each session.
- Progression: None.

## Outcomes

### CRP
Status: no clear change
CRP did not significantly change after either HIIT or endurance cycling.

Favours: no_difference

### Cytokines
Status: no clear change
IL-1beta, IL-6, IL-10, and IGF-1 did not significantly change from baseline after either protocol.

Favours: no_difference

### IL-6/IL-10
Status: improved
Endurance cycling reduced the IL-6/IL-10 ratio 30 minutes post-exercise.

Effect: -20%; P value/detail: 0.047; Favours: comparator

### MCP-1
Status: improved
Endurance cycling reduced MCP-1 two days after exercise.

Effect: -17.9%; P value/detail: 0.03; Favours: comparator

## Practical Insights

- A very low-volume cycling HIIT session can be implemented with six 30-second all-out bouts and long recoveries, but this protocol may not be tolerable for every untrained participant.
- Acute biomarker equivalence should not be presented as evidence that HIIT improves long-term inflammation.

## Limitations

- Very small analytic sample.
- Acute single-session design.
- Healthy young adults only.
- Biomarker outcomes rather than fitness, adherence, or clinical outcomes.
- One participant could not complete the HIIT protocol.

## Safety And Adherence

- No adverse events were reported in the article.
- One recruited participant was excluded because they could not complete the HIIT session.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/27212809/) (pubmed)
- [DOI](https://doi.org/10.1155/2016/5474837) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4861798/) (full text)

## Agent Guidance

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