# Caffeine-augmented Sprint interval training outcomes in obese women: an examination by inter-individual analysis on physical and physiological adaptive responses

PMID: 41262740
Journal: Frontiers in Nutrition
Published: 2025 Nov 4
Authors: Zhao X, Liu Y

## Question

Does 3 mg/kg caffeine before short sprint interval training enhance physical and physiological adaptations in overweight or obese women?

## Summary

In 30 sedentary overweight or obese young women, 12 weeks of short sprint interval training improved fat mass, strength, VO2peak, fasting glucose, lipids, and adipokines. Taking 3 mg/kg caffeine one hour before training produced statistically greater changes than placebo for several outcomes, but effects were small for some measures and the sample was small.

## Population

- Sedentary overweight or obese young women with low caffeine intake.
- Sample size: 30
- Age: Group means 22.1-23.5 years
- Sex: Women
- Fitness level: Sedentary
- Health status: Overweight or obese, otherwise healthy

## Methodology

- Randomized controlled three-arm intervention
- 12 weeks of training within a 15-week study period
- Supervised gym-based running sprint interval training
- Randomized and controlled study design.

## Protocol

- Caffeine plus short SIT.
- Modality: Running sprints.
- Work intervals: 5 seconds all-out.
- Recovery: 25 seconds self-paced running/walking; 3 minutes between sets.
- Sets or repetitions: 3 x 10 sprints.
- Intensity: All-out; caffeine 3 mg/kg 1 hour before session.
- Session duration: About 40 minutes including warm-up/cooldown.
- Frequency: 3 sessions/week.
- Program length: 12 weeks.
- Progression: None reported.
- Placebo SIT and no-training control.
- Modality: Same SIT for placebo; no structured exercise for control.
- Work intervals: 5 seconds all-out in placebo group.
- Recovery: 25 seconds in placebo group.
- Sets or repetitions: 3 x 10 sprints in placebo group.
- Intensity: All-out; placebo cellulose 3 mg/kg.
- Session duration: About 40 minutes in placebo group.
- Frequency: 3 sessions/week in placebo group.
- Program length: 12 weeks.
- Progression: None reported.

## Outcomes

### Training effects
Status: improved
Both caffeine and placebo SIT improved all measured variables versus control.

p=0.001 across variables versus control.

### Caffeine augmentation
Status: improved
Caffeine produced greater fat mass, strength, VO2peak, fasting glucose, leptin, adiponectin, and irisin changes than placebo.

Fat mass p=0.047, strength p=0.042, VO2peak p=0.011, fasting glucose p=0.018.

### Lipids
Status: no clear change
Caffeine did not add meaningful lipid improvements over placebo.

No significant group-time interaction between training groups for lipids.

## Practical Insights

- Very short 5-second sprints can be programmed in repeated sets for overweight/obese young women under supervision.
- Caffeine may slightly augment some responses, but non-caffeine SIT still improved outcomes.

## Limitations

- Small groups of n=10.
- Young women only.
- No formal blinding-efficacy assessment.
- Mechanisms were inferred rather than directly tested.

## Safety And Adherence

- All training-group participants attended all sessions.
- No injuries or caffeine-related side effects were reported.
- Participants were screened for lower-body injuries, musculoskeletal/neurological/orthopedic conditions, chronic disease, endocrine disorders, diabetes, menstrual disorders, and supplement/drug/hormone use; sessions were closely supervised.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/41262740/) (pubmed)
- [DOI](https://doi.org/10.3389/fnut.2025.1655449) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12623393/) (full text)

## Agent Guidance

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