PMID 41262740

Research
All papers

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

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.

Methodology

  • Sedentary overweight or obese young women with low caffeine intake.
  • 30 participants.
  • Running sprints.
  • Work intervals: 5 seconds all-out.
  • Recovery: 25 seconds self-paced running/walking; 3 minutes between sets.
  • Intensity: All-out; caffeine 3 mg/kg 1 hour before session.
  • About 40 minutes including warm-up/cooldown.
  • 3 sessions/week.
  • 12 weeks.
  • Randomized controlled three-arm intervention
  • Fat mass, Strength and VO2peak, and Glucose, lipids, adipokines were tracked.

Outcomes

Training effects

Both caffeine and placebo SIT improved all measured variables versus control.

p=0.001 across variables versus control.

Improved

Caffeine augmentation

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.

Improved

Lipids

Caffeine did not add meaningful lipid improvements over placebo.

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

No clear change

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

  • 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.