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Published on: March 15, 2019
Synergy or Dominance? The Ergogenic Effects of Caffeine and Carbohydrate on High-Intensity Interval Exercise
Hao Li1, Yixiang Peng2, Baiyu Liu3
1School of Athletic Performance, Shanghai University of Sport, Shanghai 200438, China.
Nutrients
|June 26, 2026
Summary
Combining caffeine (CAF) and carbohydrate (CHO) significantly boosts high-intensity interval exercise (HIIE) performance. Mouth rinsing CHO with CAF offers greater benefits than ingestion, though more research is needed.
Area of Science:
- Sports Science
- Exercise Physiology
- Nutritional Science
Background:
- High-intensity interval exercise (HIIE) demands significant physiological output.
- Caffeine (CAF) and carbohydrate (CHO) are known ergogenic aids.
- The combined effects of CAF and CHO on HIIE performance require further quantification.
Purpose of the Study:
- To meta-analyze the ergogenic effects of combined caffeine and carbohydrate (CAF + CHO) on HIIE performance.
- To identify moderating factors influencing CAF + CHO efficacy in HIIE.
- To assess the impact of different CHO administration methods (mouth rinse vs. ingestion).
Main Methods:
- Systematic search of four databases for randomized crossover trials.
- Inclusion of studies measuring HIIE performance (time, distance, work) with CAF + CHO.
- Three-level random-effects meta-analysis to calculate pooled effect sizes (Hedge's g).
- Subgroup analyses exploring control group type, CHO administration, and training status.
Main Results:
- Eleven studies (n=105) met inclusion criteria.
- CAF + CHO significantly enhanced HIIE performance (g = 0.44).
- Mouth rinsing CAF + CHO showed superior effects (g = 0.91) compared to ingestion (g = 0.33).
- Publication bias was detected, and evidence certainty was low (GRADE).
Conclusions:
- Combined caffeine and carbohydrate (CAF + CHO) effectively enhances HIIE performance.
- CHO mouth rinsing appears more beneficial than ingestion when combined with CAF.
- Preliminary evidence suggests caffeine's key role; further high-quality research is needed, especially with female participants.
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