# Influence of high-intensity interval training to exhaustion on the directional sensitivity of the cerebral pressure-flow relationship in young endurance-trained men

PMID: 35822439
Journal: Physiological reports
Published: 2022 Jul
Authors: Abbariki F, Roy MA, Labrecque L, Drapeau A, Imhoff S, Smirl JD, Brassard P

## Question

Does six weeks of high-intensity interval training to exhaustion alter directional sensitivity of the cerebral pressure-flow relationship in young endurance-trained men?

## Summary

In young endurance-trained men, six weeks of cycling HIIT to exhaustion improved VO2max and lowered resting heart rate. Cerebrovascular pressure-flow responses changed in a frequency- and direction-specific way, but these are mechanistic surrogate outcomes rather than direct app-user performance outcomes.

## Population

- Young endurance-trained men
- Sample size: 18
- Age: 27 +/- about 5-6 years
- Sex: Male
- Fitness level: Endurance-trained, baseline VO2max 55.5 +/- 4.7 ml/kg/min
- Health status: No reported cerebrovascular or cardiovascular disease

## Methodology

- Secondary analysis of a randomized training study with pooled HIIT groups
- 6 weeks
- Laboratory cycling training and cerebrovascular testing
- Randomized study design.

## Protocol

- Cycling HIIT to exhaustion.
- Modality: Cycle ergometer.
- Work intervals: 1-7 minutes at 85% maximal aerobic power or 30-60 seconds at 115%.
- Recovery: Active recovery at 50% maximal aerobic power or 150 W if maximal power was under 300 W.
- Sets or repetitions: Repeated efforts to exhaustion; number varied.
- Intensity: 85% or 115% maximal aerobic power.
- Session duration: Varied.
- Frequency: 3 sessions per week.
- Program length: 6 weeks.
- Progression: Session duration varied to reduce monotony.

## Outcomes

### VO2max
Status: improved
VO2max increased after six weeks of HIIT.

55.5 +/- 4.7 to 58.7 +/- 4.1 ml/kg/min; +5.8%; p=0.008.

### Resting HR
Status: improved
Resting heart rate decreased after training.

54 +/- 8 to 51 +/- 7 bpm; p=0.002.

### Pressure-flow sensitivity
Status: mixed
Directional sensitivity changed differently by squat-stand frequency.

At 0.05 Hz post-training, MAP increases exceeded decreases, p=0.002; at 0.10 Hz, pre-training directional sensitivity disappeared post-training, p=0.359.

### Resting cerebrovascular state
Status: no clear change
Resting MAP, MCAv, and PETCO2 did not significantly change.

Reported as non-significant.

## Practical Insights

- Exhaustion-based cycling HIIT can still improve VO2max in endurance-trained men.
- Cerebrovascular findings should be treated as mechanistic, not user-facing performance claims.
- Hard HIIT sessions in trained athletes were separated by 48-72 hours.

## Limitations

- Small sample.
- Male endurance-trained athletes only.
- No non-HIIT or non-training control group.
- Secondary analysis.
- Transcranial Doppler velocity is a surrogate that assumes stable vessel diameter.
- PETCO2 data were incomplete because of technical issues.

## Safety And Adherence

- No adverse events were reported.
- One participant was excluded because post-training tests were incomplete.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/35822439/) (pubmed)
- [DOI](https://doi.org/10.14814/phy2.15384) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9277516/) (full text)

## Agent Guidance

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