# Cardiorespiratory fitness and aerobic performance adaptations to a 4-week sprint interval training in young healthy untrained females

PMID: 28479931
Journal: Sport sciences for health
Published: 2017
Authors: Kavaliauskas M, Steer TP, Babraj JA

## Question

Can 4 weeks of low-volume cycling sprint interval training improve cardiorespiratory fitness and aerobic performance in young untrained women?

## Summary

Eight healthy untrained young women completed eight cycling sprint-interval sessions over 4 weeks. The 4 x 30 s all-out protocol improved time to exhaustion, 10 km cycling time-trial performance, critical power, and training peak-power output, but it did not significantly improve peak oxygen uptake.

## Population

- Eight healthy untrained young women.
- Sample size: 8
- Age: 21 +/- 1 years
- Sex: Women only
- Fitness level: Untrained; less than 60 min exercise 2-3 times/week
- Health status: Healthy; lower-limb injury and chronic health condition excluded

## Methodology

- Single-group repeated-measures intervention with a 4-week control period
- 4-week control period plus 4-week SIT intervention
- Laboratory cycling tests and supervised cycle ergometer training

## Protocol

- Cycling sprint interval training.
- Modality: Cycle ergometer.
- Work intervals: 30 s.
- Recovery: 4 min low-cadence unloaded cycling.
- Sets or repetitions: 4 sprints.
- Intensity: All-out against 7% body mass.
- Session duration: About 14 min sprint/recovery block.
- Frequency: 2 sessions/week.
- Program length: 4 weeks.
- Progression: No prescribed progression.
- Control period.
- Modality: Usual diet and exercise pattern.
- Program length: 4 weeks.
- Progression: None.

## Outcomes

### TTE
Status: improved
Time to exhaustion improved after SIT.

+12 +/- 4%, p=0.001.

### 10 km TT
Status: improved
10 km cycling time trial was faster after SIT.

-6 +/- 4%, p=0.004.

### VO2peak
Status: no clear change
VO2peak did not significantly change after eight SIT sessions.

Pre-SIT-2 31.7 +/- 3.0 vs post-SIT 30.9 +/- 4.5 ml/kg/min; p>0.05.

## Practical Insights

- Very short all-out sprint blocks may improve cycling performance even without VO2peak gains.
- Twice-weekly SIT may be below the dose needed for cardiorespiratory-fitness improvement.

## Limitations

- Small sample
- No parallel control group
- Women only
- Diet and outside exercise not monitored
- Short intervention

## Safety And Adherence

- No adverse events or injuries were reported.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/28479931/) (pubmed)
- [DOI](https://doi.org/10.1007/s11332-016-0313-x) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5397461/) (full text)

## Agent Guidance

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