# Similar Inflammatory Responses following Sprint Interval Training Performed in Hypoxia and Normoxia

PMID: 27536249
Journal: Frontiers in physiology
Published: 2016
Authors: Richardson AJ, Relf RL, Saunders A, Gibson OR

## Question

Do 2 weeks of sprint interval training in normoxia versus normobaric hypoxia produce different aerobic-performance adaptations and inflammatory responses?

## Summary

In 42 untrained but recreationally active young adults, 2 weeks of all-out cycling sprint interval training improved VO2peak, time to exhaustion, and power at anaerobic threshold in both normoxia and hypoxia. Hypoxia did not exacerbate resting inflammatory responses compared with normoxia.

## Population

- Untrained but recreationally active young adults.
- Sample size: 42
- Age: 21 +/- 1 years
- Sex: 27 men and 15 women
- Fitness level: Untrained but recreationally active; usual unstructured training <2 h/week.
- Health status: Non-smokers; no altitude exposure above 2000 m in prior 2 months.

## Methodology

- Randomized controlled training study with hypoxic SIT, normoxic SIT, and non-training control groups
- 2 weeks
- Normobaric hypoxic chamber and exercise physiology laboratory
- Randomized and controlled study design.

## Protocol

- Sprint interval training.
- Modality: Cycling.
- Work intervals: 30 s all-out sprint.
- Recovery: 4 min active cycling at 60 W.
- Sets or repetitions: 4-7 repetitions.
- Intensity: All-out against 0.075 kg/kg body mass.
- Session duration: Varied by sprint count.
- Frequency: 6 sessions over 2 weeks.
- Program length: 2 weeks.
- Progression: Sprints increased from 4 to 7.
- Normoxia/hypoxia/control comparators.
- Modality: Same SIT in FiO2 0.2093 or FiO2 0.15; control no training.
- Work intervals: 30 s all-out sprint for SIT groups.
- Recovery: 4 min active recovery for SIT groups.
- Sets or repetitions: 4-7 for SIT groups.
- Intensity: Same all-out prescription; environmental oxygen differed.
- Session duration: Varied by sprint count.
- Frequency: 6 sessions over 2 weeks for SIT groups.
- Program length: 2 weeks.
- Progression: Same sprint progression.

## Outcomes

### VO2peak
Status: improved
VO2peak improved in hypoxia and normoxia but not control.

HYP +11.9%, p=0.001; NORM +9.8%, p=0.002; CONT +0.9%, p=0.906.

### TTE
Status: improved
Time to exhaustion improved similarly in both SIT groups.

HYP 633 +/- 330 to 787 +/- 326 s; NORM 589 +/- 373 to 729 +/- 351 s; both p=0.001.

### Inflammation
Status: mixed
IL-6 and TNF-alpha increased after SIT, but hypoxia did not exacerbate the response versus normoxia.

IL-6 HYP +17.4%, NORM +20.1%; TNF-alpha HYP +10.8%, NORM +12.9%.

### Sprint power
Status: no clear change
Peak and mean Wingate power did not significantly change between groups.

Peak power pre-post p=0.530; mean power pre-post p=0.653.

## Practical Insights

- Six sessions of 30 s all-out cycling sprints can improve aerobic performance in young active adults.
- A hypoxic chamber did not provide enough extra benefit to justify general use for most outcomes.
- Inflammatory markers may remain elevated 48 h after the final SIT session.

## Limitations

- Short intervention
- Young healthy sample
- All-out cycling only
- Hypoxic chamber setting
- No explicit adverse-event reporting
- Limited inflammatory markers

## Safety And Adherence

- Adverse events were not reported.
- Participants were informed of study procedures and risks, provided written consent, were non-smokers, and had no recent altitude exposure above 2000 m.
- Training was supervised with HR, SpO2, and RPE monitoring, but attendance, dropout, and injury details were not reported in the main text reviewed.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/27536249/) (pubmed)
- [DOI](https://doi.org/10.3389/fphys.2016.00332) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4971433/) (full text)

## Agent Guidance

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