# Age related vascular endothelial function following lifelong sedentariness: positive impact of cardiovascular conditioning without further improvement following low frequency high intensity interval training

PMID: 25626864
Journal: Physiological Reports
Published: 2015 Jan 1
Authors: Grace FM, Herbert P, Ratcliffe JW, New KJ, Baker JS, Sculthorpe NF

## Question

Can cardiovascular conditioning and then low-frequency HIIT improve age-related endothelial function in lifelong sedentary older men?

## Summary

In older sedentary men, 6 weeks of supervised cardiovascular conditioning improved vascular endothelial function, while adding low-frequency HIIT afterward improved aerobic capacity but did not further improve flow-mediated dilation. Lifelong exercisers served as a comparison group and maintained high vascular function.

## Population

- Older men classified as lifelong sedentary or lifelong exercisers.
- Sample size: 44
- Age: About 61-63 years
- Sex: Men
- Fitness level: Lifelong sedentary or lifelong exerciser
- Health status: Screened older adults

## Methodology

- Prospective nonrandomized cohort intervention with lifelong exerciser comparison group
- 12 weeks total: 6 weeks conditioning plus 6 weeks low-frequency HIIT
- Supervised exercise and vascular physiology laboratory in South Wales, UK
- Controlled study design.

## Protocol

- Low-frequency HIIT after conditioning.
- Modality: Wattbike cycling.
- Work intervals: 30 seconds.
- Recovery: 3 minutes active recovery at low resistance.
- Sets or repetitions: 6.
- Intensity: 40%-50% peak power; target peak HR >90% HRR.
- Frequency: Once every 5 days.
- Program length: 6 weeks.
- Progression: First 3 sessions at 40% peak power, then 50%.
- Conditioning phase and lifelong exerciser comparison.
- Modality: Walking, walk/jogging, jogging, cycling.
- Intensity: 55%-65% HRR during conditioning.
- Session duration: 150 minutes/week target during conditioning.
- Frequency: Weekly volume-based.
- Program length: 6 weeks.
- Progression: 55% HRR weeks 1-2, 60% weeks 3-4, brief 60%-65% bursts in final 2 weeks.

## Outcomes

### FMD
Status: improved
Sedentary men improved FMD after conditioning.

SED phase A to B p<0.001.

### FMD
Status: no clear change
Low-frequency HIIT did not further improve FMD after conditioning.

SED phase B to C p=1.0.

### Aerobic capacity
Status: improved
Low-frequency HIIT improved aerobic capacity in both groups.

About +8.3% SED and +7.4% LEX.

## Practical Insights

- For older sedentary users, build conditioning before HIIT.
- Low-frequency HIIT may improve aerobic capacity even if vascular FMD gains have already occurred with conditioning.

## Limitations

- Nonrandomized cohort design.
- No negative control for the second 6-week phase.
- Men only.
- Biomarker analyses were not the primary powered endpoint.

## Safety And Adherence

- Applicants required GP approval and PAR-Q screening; three applicants were advised to withdraw before enrollment because of risk.
- Sedentary participants completed 6 weeks of conditioning before low-frequency HIIT.
- Low-frequency HIIT had 100% adherence after conditioning and was described as well tolerated; no adverse events or injuries were reported.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/25626864/) (pubmed)
- [DOI](https://doi.org/10.14814/phy2.12234) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4387763/) (full text)

## Agent Guidance

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