# High-intensity interval training improves acute plasma volume responses to exercise that is age dependent

PMID: 29464883
Journal: American Journal of Physiology-Regulatory, Integrative and Comparative Physiology
Published: 2018
Authors: Jabbour G, Iancu HD, Zouhal H, Mauriège P, Joanisse DR, Martin LJ

## Question

Does a 6-week high-intensity interval training program alter plasma volume responses to acute exercise and related age or blood-pressure associations in sedentary adults?

## Summary

A six-week supervised cycling sprint program in sedentary adults lowered blood pressure and reduced acute exercise-related plasma volume losses, with age-related plasma volume effects present before but not after training.

## Population

- Sedentary healthy university staff.
- Sample size: 30
- Age: Mean 38 years; range 18-71
- Sex: 10 men, 20 women
- Fitness level: Sedentary
- Health status: Healthy after screening

## Methodology

- Single-group pre-post intervention
- 6 weeks
- Laboratory cycle ergometer training

## Protocol

- 6-second cycle HIT.
- Modality: Cycle ergometer.
- Work intervals: 6 s maximal sprint.
- Recovery: 2 min passive recovery.
- Sets or repetitions: 6.
- Intensity: Maximal sprint against individualized resistance.
- Session duration: Approximately 15 min.
- Frequency: 3 sessions/week.
- Program length: 6 weeks.
- Progression: Resistance adjusted every 2 weeks.

## Outcomes

### Plasma volume
Status: improved
Acute exercise-related plasma volume decreases were smaller after HIT.

Warm-up and supramaximal cycling p<0.001.

### Blood pressure
Status: improved
Resting systolic and diastolic blood pressure decreased.

SBP 114.5 to 109.1 mmHg; DBP 78.3 to 71.6 mmHg; p<0.001.

### VO2max
Status: no clear change
VO2max did not significantly change.

## Practical Insights

- Very low total sprint work can still affect blood pressure and plasma volume responses.
- Maximal sprint protocols need careful screening and are not a casual beginner format.

## Limitations

- No control group
- Hydration/osmolality measures not assessed
- Age subgroup analyses need further study

## Safety And Adherence

- No adverse events were reported.
- All participants completed all training sessions and the article states no other difficulties were encountered.
- Screening excluded cardiovascular and chronic disease, smoking, drug consumption, and orthopedic or neurological disease; testing included ECG/heart-rate monitoring.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/29464883/) (pubmed)
- [DOI](https://doi.org/10.1152/ajpregu.00363.2017) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5820462/) (full text)

## Agent Guidance

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