# The Impact of Sprint Interval Training Frequency on Blood Glucose Control and Physical Function of Older Adults

PMID: 31936725
Journal: International Journal of Environmental Research and Public Health
Published: 2020 Jan 10
Authors: Adamson S, Kavaliauskas M, Lorimer R, Babraj J

## Question

Does once-weekly versus twice-weekly short sprint interval training improve blood glucose control, physical function, and aerobic capacity in older adults?

## Summary

In inactive older adults with controlled hypertension, 8 weeks of supervised cycling sprint interval training once or twice weekly improved physical function and predicted aerobic capacity compared with control. Twice-weekly training produced clearer improvements in 2-hour glucose and glucose area under the curve.

## Population

- Inactive older adults with stable controlled hypertension and no metabolic or cardiovascular disease.
- Sample size: 34
- Age: 65 +/- 3 years
- Sex: 13 men and 21 women
- Fitness level: Inactive
- Health status: Well-controlled hypertension with unchanged medication for 6 months

## Methodology

- Three-group controlled training intervention
- 8 weeks
- Abertay University supervised laboratory training
- Controlled study design.

## Protocol

- Once-weekly cycling SIT.
- Modality: Cycle ergometer.
- Work intervals: 6 s all-out sprint.
- Recovery: At least 60 s passive recovery or until HR <120 bpm.
- Sets or repetitions: 6 progressing to 10 sprints.
- Intensity: All-out against 7% body mass for men and 6.5% for women.
- Session duration: Short session with 36-60 s total sprint work plus recovery.
- Frequency: 1 session/week.
- Program length: 8 weeks.
- Progression: Add one sprint per week until 10 by week 5.
- Twice-weekly cycling SIT and no-exercise control.
- Modality: Cycle ergometer for SIT; usual lifestyle for control.
- Work intervals: 6 s all-out sprint in SIT comparator.
- Recovery: At least 60 s passive recovery or until HR <120 bpm.
- Sets or repetitions: 6 progressing to 10 sprints.
- Intensity: All-out against sex-specific body-mass resistance.
- Session duration: Short session with 36-60 s total sprint work plus recovery.
- Frequency: 2 sessions/week for SIT comparator.
- Program length: 8 weeks.
- Progression: Add one sprint per week until 10 by week 5.

## Outcomes

### 2 h glucose
Status: mixed
Twice-weekly SIT significantly reduced 2 h glucose; once-weekly did not reach significance but exceeded the smallest worthwhile change.

Group x time p=0.001; twice-weekly p=0.001; once-weekly p=0.249.

### Glucose AUC
Status: mixed
Twice-weekly SIT significantly reduced glucose AUC; once-weekly did not reach significance but improved beyond SWC.

Group x time p=0.027; twice-weekly p=0.007; once-weekly p=0.124.

### Function
Status: improved
Both SIT frequencies improved get-up-and-go and sit-to-stand times.

GUAG group x time p=0.014; STS p=0.001.

### Predicted VO2max
Status: improved
Both SIT frequencies increased predicted VO2max by about 1.5 mL/kg/min.

Group x time p=0.002; once and twice p=0.001.

## Practical Insights

- For selected older adults, very short supervised cycling sprints may improve function with minimal weekly frequency.
- Use heart-rate recovery thresholds instead of fixed recovery only.
- Twice-weekly volume may be needed for clearer glucose-control changes.

## Limitations

- Small sample
- Allocation was not clearly randomized
- Frequency and total sprint volume were confounded
- Predicted rather than directly measured VO2max
- Limited adverse-event detail

## Safety And Adherence

- No adverse events were reported.
- All SIT sessions were fully supervised with continuous heart-rate monitoring.
- Participants had controlled hypertension only; metabolic and cardiovascular disease were exclusion criteria, and recovery continued until at least 60 seconds or heart rate below 120 bpm.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/31936725/) (pubmed)
- [DOI](https://doi.org/10.3390/ijerph17020454) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7013863/) (full text)

## Agent Guidance

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