PMID 24520199

Research
All papers

High-intensity interval training induces a modest systemic inflammatory response in active, young men

Zwetsloot KA, John CS, Lawrence MM, Battista RA, Shanely RA

Question

How much does acute cycling HIIT increase systemic inflammatory cytokines and chemokines, and does two weeks of HIIT training alter that response?

Summary

Eight healthy recreationally active young men completed six cycling HIIT sessions over two weeks. A single HIIT bout produced modest increases in several inflammatory cytokines and chemokines, two weeks of training did not blunt that response, and peak cycling power improved despite no significant VO2max change.

Methodology

  • Eight healthy recreationally active young men
  • 8 participants.
  • Cycle ergometer.
  • Work intervals: 60 seconds.
  • Recovery: 75 seconds active recovery at 50 W.
  • Intensity: 100% VO2max workload.
  • Approximately 21-33 minutes including warm-up/cool-down.
  • 3 sessions/week.
  • 2 weeks.
  • Single-arm short-term training study with repeated acute blood sampling
  • Inflammatory cytokines, VO2max, Peak cycling power, and Perceived exertion were tracked.

Outcomes

Cytokines

Acute HIIT modestly increased IL-6, IL-8, IL-10, TNF-alpha, and MCP-1.

Multiple acute time-point comparisons p<=0.05.

Safety concern

Training effect

Two weeks of HIIT did not alter the inflammatory response pattern.

No main effect of training reported.

No clear change

Power

Peak cycling power increased after two weeks.

p=0.007; about 4.6% increase.

Improved

VO2max

VO2max did not significantly improve after two weeks.

p=0.481.

No clear change

Insights

  • A two-week 60-second cycling HIIT progression may improve peak power before VO2max changes.
  • Modest inflammatory increases are expected after acute HIIT in screened active young men.
  • The protocol is lab-prescribed by VO2max workload, so consumer versions need simpler intensity anchors.

Limitations

  • Very small sample.
  • Men only.
  • No control group.
  • Short two-week intervention.
  • Cytokine analyses used n=7 after one outlier exclusion.
  • Clinical and immunocompromised populations were not studied.

Safety

  • Adverse events were not explicitly reported.
  • All eight participants completed all study components.
  • Participants were screened as nonsmokers with no cardiovascular, pulmonary, neuromuscular disease, no lower-body musculoskeletal injury in the prior 6 months, and VO2max at least 42.2 ml/kg/min.
  • One participant's inflammatory-marker data were excluded from cytokine analyses because values were abnormally high at rest and in response to exercise.