# Comparison of cerebrovascular reactivity recovery following high-intensity interval training and moderate-intensity continuous training

PMID: 32506845
Journal: Physiological reports
Published: 2020 Jun
Authors: Burma JS, Macaulay A, Copeland P, Khatra O, Bouliane KJ, Smirl JD

## Question

How long do cerebrovascular reactivity measures remain altered after acute HIIT compared with moderate continuous exercise and rest?

## Summary

In nine young adults, a single cycling HIIT session temporarily reduced cerebrovascular reactivity to high carbon dioxide for about one hour, with recovery by two hours. Moderate continuous cycling produced smaller or limited changes, and quiet rest was stable.

## Population

- Nine healthy young adults from a university setting.
- Sample size: 9
- Age: 26 +/- 5 years
- Sex: 7 male, 2 female
- Fitness level: Moderate to good fitness
- Health status: Apparently healthy

## Methodology

- Randomized acute repeated-measures laboratory comparison
- Single-day conditions with 8 hours of follow-up; conditions separated by at least 3 days
- University exercise and cerebrovascular physiology laboratory
- Randomized and controlled study design.

## Protocol

- HIIT cycling.
- Modality: Cycle ergometer.
- Work intervals: 1 minute.
- Recovery: Active cycling recovery between intervals; exact duration not clearly reported.
- Sets or repetitions: 10 intervals.
- Intensity: 85-90% heart-rate reserve.
- Session duration: 25 minutes.
- Frequency: Single acute session.
- Program length: One session.
- Progression: None.
- MICT and quiet rest.
- Modality: Cycle ergometer for MICT; seated quiet rest for control.
- Intensity: MICT at 50-60% HRR; control quiet rest.
- Session duration: 45 minutes MICT; 30 minutes control.
- Frequency: Single acute comparator condition each.
- Program length: One session each.
- Progression: None.

## Outcomes

### Hypercapnic CVR
Status: worse/safety concern
HIIT attenuated MCA/PCA hypercapnic slopes immediately and at 1 hour, with recovery by 2 hours.

At least 37% reductions; all p<0.018 for post-HIIT changes.

### Hypocapnic CVR
Status: no clear change
Hypocapnic slopes did not differ by condition.

All p>0.310.

### MICT CVR
Status: mixed
MICT produced limited decreases in relative hypercapnic MCA slope but not the broader HIIT pattern.

Relative MCA slope decreased 20% at hour 0 and 16% at hour 1.

## Practical Insights

- A two-hour recovery buffer may be adequate before CVR testing after HIIT in healthy young adults.
- HIIT and MICT should not be treated as interchangeable when acute cerebrovascular reactivity is the outcome.

## Limitations

- Very small sample.
- TCD velocity assumes stable vessel diameter.
- VO2max was not measured for prescription.
- Healthy young adults limit generalizability.

## Safety And Adherence

- The article did not report adverse events.
- Participants were medically screened by history and monitored with ECG, blood pressure, PETCO2, TCD, and gas analysis during supervised laboratory testing.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/32506845/) (pubmed)
- [DOI](https://doi.org/10.14814/phy2.14467) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7276190/) (full text)

## Agent Guidance

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