# A Shorter-Bout of HIIT Is More Effective to Promote Serum BDNF and VEGF-A Levels and Improve Cognitive Function in Healthy Young Men

PMID: 35846013
Journal: Frontiers in physiology
Published: 2022
Authors: Li Q, Zhang L, Zhang Z, Wang Y, Zuo C, Bo S

## Question

Do 20-minute and 30-minute acute HIIT bouts differ in effects on serum BDNF, VEGF-A, stress hormones, and cognitive performance?

## Summary

In 12 active healthy young men, a 20-minute cycling HIIT bout improved several short-term cognitive measures and acutely increased serum BDNF, while a 30-minute bout produced more lactate, higher perceived exertion, and less favorable cognitive and hormonal responses.

## Population

- Active healthy right-handed young men from a university setting.
- Sample size: 12
- Age: 18-25 years
- Sex: Male
- Fitness level: Active healthy young men
- Health status: Healthy, nonsmoking, no acute or chronic disease reported

## Methodology

- Randomized crossover acute exercise study
- Two acute HIIT visits separated by one week
- Laboratory cycling and blood/cognitive testing
- Randomized and controlled study design.

## Protocol

- 20-minute cycling HIIT.
- Modality: Cycle ergometer.
- Work intervals: 1 minute.
- Recovery: 1 minute active recovery.
- Sets or repetitions: 10 cycles.
- Intensity: 85% VO2peak work, 25% VO2peak recovery.
- Session duration: 20-minute interval block plus 5-minute warm-up and 5-minute cooldown.
- Frequency: Single acute bout.
- Program length: Single session.
- 30-minute cycling HIIT.
- Modality: Cycle ergometer.
- Work intervals: 1 minute.
- Recovery: 1 minute active recovery.
- Sets or repetitions: 15 cycles.
- Intensity: 85% VO2peak work, 25% VO2peak recovery.
- Session duration: 30-minute interval block plus 5-minute warm-up and 5-minute cooldown.
- Frequency: Single acute bout.
- Program length: Single session.

## Outcomes

### BDNF
Status: improved
BDNF increased immediately after the 20-minute bout but not after the 30-minute bout.

20-min: 21.29 +/- 1.17 to 26.66 +/- 1.32, p<0.001; 30-min decreased below baseline at 30 min, p=0.013.

### VEGF-A
Status: mixed
VEGF-A rose immediately after both bouts, then returned to baseline after 20 minutes and fell below baseline after 30 minutes.

Immediate increases in both conditions; below baseline after 30-min bout at 30 minutes.

### Stroop RT
Status: improved
The 20-minute bout shortened several Stroop reaction times; the 30-minute bout did not improve reaction time.

20-min improved congruent and neutral RT immediately and at 30 min, and incongruent RT immediately p=0.043.

### Digit span
Status: improved
Digit span improved after the 20-minute bout but not after the 30-minute bout.

DST-F improved immediately and 30 min; DST-B improved immediately after 20-min HIIT.

### RPE
Status: worse/safety concern
Perceived exertion was higher after the 30-minute bout.

RPE 14.417 +/- 1.165 for 20-min and 16.417 +/- 0.996 for 30-min.

## Practical Insights

- More HIIT volume was not better for short-term cognition and biomarker response in this small acute study.
- A 20-minute 1:1 cycling interval block at 85% VO2peak showed more favorable acute responses than a 30-minute block.
- The biomarker findings should be used cautiously because they are surrogate outcomes from a small homogeneous sample.

## Limitations

- Very small sample of 12 young men.
- Acute study only.
- Only selected cognitive tasks were assessed.
- Only neurotrophins and hormones were measured; neural activation was not measured.
- Right-handed active young men only.

## Safety And Adherence

- No adverse events were reported in the extracted text.
- Participants were screened for health status and smoking/alcohol history.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/35846013/) (pubmed)
- [DOI](https://doi.org/10.3389/fphys.2022.898603) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9277476/) (full text)

## Agent Guidance

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