# Cerebrovascular response to an acute bout of low-volume high-intensity interval exercise and recovery in young healthy adults

PMID: 34882027
Journal: Journal of applied physiology (Bethesda, Md. : 1985)
Published: 2022 Jan 1
Authors: Whitaker AA, Aaron SE, Kaufman CS, Kurtz BK, Bai SX, Vidoni ED, Montgomery RN, Billinger SA

## Question

How does middle cerebral artery blood velocity respond during and after a 10-minute low-volume HIIT bout in young healthy adults?

## Summary

In 24 analyzed young healthy adults, a 10-minute recumbent-stepper HIIT bout increased middle cerebral artery velocity during exercise, lowered it immediately after exercise, and returned it to baseline by 30 minutes. No adverse events occurred and all participants maintained the prescribed workload.

## Population

- Young healthy adults
- Sample size: 24
- Age: 25 +/- 2 years
- Sex: 12 women and 12 men analyzed
- Fitness level: Mixed active young adults; estimated VO2max 44.7 +/- 6.8 ml/kg/min
- Health status: Low cardiac risk and less than 50% carotid stenosis

## Methodology

- Acute single-group physiological study
- Single acute HIIT visit after familiarization and screening
- Laboratory recumbent stepper testing

## Protocol

- Low-volume recumbent-stepper HIIE.
- Modality: Recumbent stepper.
- Work intervals: 1 minute at about 70% estimated Wattmax.
- Recovery: 1 minute active recovery at about 10% estimated Wattmax.
- Sets or repetitions: 10 minutes alternating intervals; started with active recovery.
- Intensity: High intervals averaged 134 +/- 37 W and 71 +/- 5% estimated Wattmax.
- Session duration: 10 minutes plus 2-minute cool-down.
- Frequency: Single session.
- Program length: Single session.
- Progression: None.
- Baseline and recovery.
- Modality: Seated rest.
- Intensity: Rest.
- Session duration: 20-minute baseline plus immediate and 30-minute recovery recordings.
- Frequency: Within-session comparison.
- Program length: Single session.
- Progression: None.

## Outcomes

### MCAv during HIIT
Status: mixed
MCAv rose above baseline during HIIT rather than decreasing as hypothesized.

MCAv higher than baseline during minutes 1-10, p<=0.003.

### MCAv recovery
Status: mixed
MCAv was lower immediately after exercise and returned to baseline by 30 minutes.

Immediate post vs baseline p<0.001; 30-minute post p=0.47.

### MAP
Status: mixed
MAP increased during HIIT and returned to baseline in recovery.

During HIIT p<0.001; immediate post p=0.25; 30-minute post p=0.12.

### Safety completion
Status: improved
No adverse events occurred and all analyzed participants maintained the workload.

## Practical Insights

- A 10-minute 1:1 interval format can be tolerated by screened young adults under supervision.
- Add a cool-down after short hard intervals.
- Do not translate acute MCAv changes into consumer benefit claims.

## Limitations

- Acute single-group design.
- Young healthy low-risk sample.
- No non-exercise control condition.
- MCA diameter was not directly measured.
- Exercise intensity was based on estimated maximal workload.
- PETCO2 measurement may have influenced breathing.

## Safety And Adherence

- No adverse events occurred.
- All analyzed participants maintained prescribed workload.
- One participant was excluded because transcranial Doppler signal was lost.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/34882027/) (pubmed)
- [DOI](https://doi.org/10.1152/japplphysiol.00484.2021) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8759972/) (full text)

## Agent Guidance

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