The Mucosal Immune Function Is Not Compromised during a Period of High-Intensity Interval Training. Is It Time to Reconsider an Old Assumption?
Question
Does a short period of HIIT compromise mucosal immune function compared with long slow distance running in recreational runners?
Summary
In recreational male runners, 3 weeks of 4 x 4 minute high-intensity running improved treadmill performance and VO2peak without reducing salivary immune markers. Salivary IgA secretion was higher after HIIT than after longer slower running.
Methodology
- Recreational male runners.
- 28 participants.
- Running.
- Work intervals: 4 min.
- Recovery: 3 min active recovery.
- Intensity: 90-95% HRmax.
- About 35 min including warm-up.
- 3 sessions/week.
- 3 weeks.
- Controlled short-term training study
- VO2peak, Time to exhaustion, and Salivary IgA were tracked.
Outcomes
VO2peak
VO2peak improved in the HIIT group but not the long slow distance group.
Group by time interaction p=0.01.
Time to exhaustion
Both groups improved, with higher post-training time to exhaustion in HIIT than long slow distance.
Post-training between-group p=0.02.
Salivary IgA
HIIT did not reduce mucosal immune marker profiles and increased sIgA secretion rate AUC.
sIgA secretion rate AUC higher with HIIT, p=0.01.
Cortisol
Cortisol AUC was not affected differently by HIIT versus long slow distance.
Insights
- Long aerobic HIIT intervals can be verified with heart-rate targets.
- Short HIIT blocks do not necessarily imply acute mucosal immune suppression in trained runners.
Limitations
- Small male runner sample
- Short intervention
- Randomization not clearly reported
- Immune markers are surrogate outcomes
- Participants continued other training
Safety
- No adverse events or injuries were reported in the extracted NXML.
- One saliva sample was excluded because of private stress unrelated to the intervention.