# Promoting Exercise and Healthy Diet Among Primary Care Patients: Feasibility, Preliminary Outcomes, and Lessons Learned From a Pilot Trial With High Intensity Interval Exercise

PMID: 34337406
Journal: Frontiers in Sports and Active Living
Published: 2021
Authors: Smith-Ryan AE, Weaver MA, Viera AJ, Weinberger M, Blue MNM, Hirsch KR

## Question

Is a primary-care-linked home program combining HIIT and dietary support feasible for patients with cardiovascular risk factors?

## Summary

This small primary-care pilot tested a 12-week home lifestyle program combining HIIT and a daily meal replacement in adults with cardiovascular risk factors. Some completers improved fitness or risk markers, and no adverse events were reported, but dropout was high, adherence tracking was difficult, and there was no control group.

## Population

- Primary care patients with at least one cardiovascular risk factor
- Sample size: 16
- Age: 44.9 +/- 12.6 years
- Sex: Not fully summarized in extracted text
- Fitness level: At-risk primary-care adults, not athletes
- Health status: Mean BMI 33.1 +/- 5.6 with cardiovascular risk factors

## Methodology

- Single-arm pilot feasibility study
- 12-week intervention with limited 6-month follow-up
- Primary-care-linked home lifestyle intervention

## Protocol

- Home HIIT plus meal replacement.
- Modality: Home high-intensity exercise.
- Work intervals: 1 minute.
- Recovery: 1 minute active or passive rest.
- Sets or repetitions: 10 intervals.
- Intensity: 75-95% maximum heart rate.
- Session duration: About 25 minutes with warm-up.
- Frequency: 2 sessions/week required; 3 encouraged.
- Program length: 12 weeks.
- Progression: Individualized HR-zone based.

## Outcomes

### Retention
Status: worse/safety concern
Retention and initiation were major feasibility issues.

10/16 returned post; 4 did not initiate training and 2 dropped out in the first 2 weeks.

### VO2peak
Status: improved
Most completers improved cardiorespiratory fitness.

VO2peak improved in 80% of completers; mean change about +4.8 +/- 3.8 ml/kg/min in the extracted results.

### Safety
Status: no clear change
No adverse events were reported.

Descriptive safety reporting.

## Practical Insights

- For app design, adherence capture must be easier than paper logs plus disconnected wearables.
- A 10 x 1-minute interval structure is app-friendly, but high-risk users need clearance.
- Cointerventions make it hard to attribute outcomes to HIIT alone.

## Limitations

- Small sample.
- No control group.
- High dropout and non-initiation.
- Dietary meal replacement cointervention.
- Incomplete adherence tracking and limited follow-up return.

## Safety And Adherence

- No adverse events were reported.
- Screening excluded contraindications and allowed PCP concern to stop enrollment.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/34337406/) (pubmed)
- [DOI](https://doi.org/10.3389/fspor.2021.690243) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8322607/) (full text)

## Agent Guidance

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