PMID 31662994

Research
All papers

Comparison of the Effectiveness of High-Intensity Interval Training in Hypoxia and Normoxia in Healthy Male Volunteers: A Pilot Study

Żebrowska A, Jastrzębski D, Sadowska-Krępa E, Sikora M, Di Giulio C

Question

Does the same HIIT program performed in normobaric hypoxia produce different cardiorespiratory and angiogenic responses than normoxia?

Summary

Twelve active young men completed the same 3-week cycling interval program in normal oxygen and low-oxygen chamber conditions. Hypoxic training produced larger changes in VO2max and several angiogenic or nitric-oxide markers, but this pilot used specialized equipment and a small male sample.

Methodology

  • Twelve healthy physically active young men.
  • 12 participants.
  • Cycle ergometer in normobaric hypoxia.
  • Work intervals: 5 minutes.
  • Recovery: 5 minutes rest after each bout.
  • Intensity: 120% individual lactate threshold; FiO2 15.2%.
  • About 65 minutes including 15-minute acclimatization and 5-minute warm-up.
  • 3 sessions/week.
  • 3 weeks.
  • Randomized crossover pilot training study
  • VO2max, Angiogenic markers, and Cytokines were tracked.

Outcomes

VO2max

Hypoxic HIIT increased VO2max more than normoxic HIIT.

Training x group F=15.5, p<0.001; within hypoxia p=0.01.

Improved

HIF-1alpha and NO

Hypoxia increased HIF-1alpha and nitric oxide responses compared with normoxia.

HIF-1alpha and NO interactions reported around p<0.01 to p<0.05.

Improved

Cytokines

IL-1beta postexercise was higher after hypoxia, but TNF-alpha and IL-6 did not significantly change.

IL-1beta postexercise p=0.01; TNF-alpha and IL-6 p>0.05.

Mixed

Insights

  • Hypoxia may change biomarker response to the same interval dose, but the protocol is not practical for ordinary app users.
  • A 5-minute on/5-minute off cycling structure is reproducible when threshold testing is available.

Limitations

  • Pilot sample of 12 active men.
  • Short 3-week blocks.
  • Hypoxia chamber limits translation.
  • Dropout/noncompletion count was not reported.

Safety

  • The article did not report adverse events.
  • Participants were screened for hemodynamic dysfunction and recent inflammatory disease and trained under laboratory supervision with physiologic monitoring.