# Aerobically trained older adults show impaired resting, but preserved exercise-induced circulating progenitor cell count, which was not improved by sprint interval training

PMID: 36786845
Journal: Pflugers Archiv
Published: 2023-04
Authors: Yasar Z, Ross MD, Gaffney CJ, Postlethwaite RD, Wilson R, Hayes LD

## Question

Do trained older adults have altered circulating progenitor cell responses, and can eight weeks of sprint interval training improve them?

## Summary

Aerobically trained older adults had lower resting circulating progenitor cell counts than trained younger adults, but exercise still mobilized these cells. Eight weeks of twice-weekly static sprint interval training in the older group did not improve resting or exercise-induced progenitor cell counts.

## Population

- Aerobically trained young and older adults; older adults completed SIT.
- Sample size: 21
- Age: Young 28 +/- 5 years; older 67 +/- 3 years
- Sex: Young 8% female; older 22% female
- Fitness level: Aerobically trained, at least 150 min/week moderate/high exercise.
- Health status: Screened free of exercise-contraindicating disease/injury; no atrial fibrillation.

## Methodology

- Comparative physiology study with an older-adult SIT intervention
- Older adults completed 8 weeks of SIT; young adults completed a comparison test session
- Laboratory exercise testing and supervised static sprint training
- Controlled study design.

## Protocol

- Static sprint interval training.
- Modality: Static running.
- Work intervals: 20-s all-out static sprint.
- Recovery: 3-min self-paced recovery.
- Sets or repetitions: 3 sprints.
- Intensity: All-out.
- Session duration: About 15 min including warm-up and cool-down.
- Frequency: 2 sessions/week.
- Program length: 8 weeks.
- Progression: No progression reported.
- Young trained comparison and older pre-SIT.
- Modality: Graded cycle exercise test to exhaustion.
- Work intervals: Ramp test to volitional exhaustion.
- Sets or repetitions: Single GXT at each test point.
- Intensity: Volitional exhaustion with VO2max criteria.
- Frequency: Young once; older before and after SIT.
- Progression: Cycle workload increased 25 W/min after warm-up.

## Outcomes

### Resting CPC
Status: worse/safety concern
Older trained adults had lower resting CPC counts than young adults.

CD34+ 828 +/- 314 vs 1186 +/- 272 cells/mL, p=0.015.

### Exercise CPC
Status: improved
GXT increased CPC counts in both age groups.

Older CD34+ 828 to 1582, p<0.001; young 1186 to 2134, p=0.004.

### SIT effect
Status: no clear change
Eight weeks of SIT did not improve older adults' basal or exercise-induced CPC response.

Basal CD34+ 828 to 765, p=0.602; interaction p=0.233.

### Adverse events
Status: unclear
No adverse events were reported, but detailed monitoring was not described.

## Practical Insights

- Low-volume all-out static sprinting did not improve CPC biomarkers in trained older adults.
- All-out older-adult sprint protocols require screening context.

## Limitations

- Small older-adult sample.
- No sedentary comparison group.
- CPC was a secondary outcome and not powered a priori.
- No CPC functional/paracrine testing.
- Sex distribution and muscle mass may influence responses.

## Safety And Adherence

- No adverse events were reported in the full text.
- Older adults were already trained and screened with PAR-Q/ACSM procedures; SIT sessions were separated by at least 72 h.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/36786845/) (pubmed)
- [DOI](https://doi.org/10.1007/s00424-022-02785-6) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10011317/) (full text)

## Agent Guidance

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