The Study
Effects of Different Caffeine Dosages on Maximal Physical Performance and Potential Side Effects in Low-Consumer Female Athletes: Morning vs. Evening Administration
This study is like a fair test where 15 female athletes tried different caffeine pills at different times of day to see what helped them jump higher or run faster. Because they didn’t know which pill they got and the researchers didn’t either, we can say caffeine probably caused the changes we saw—but only for these specific athletes.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Teen female athletes who don't usually drink caffeine can jump higher and run faster in the morning if they take a moderate caffeine pill—but not if they take it at night.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 568 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes—these small improvements (2.5–4.5%) can make a real difference in competitive handball, but taking caffeine at night causes more sleep problems and headaches.
- 2In the morning: 6 mg/kg caffeine improved jumps by 3.8%, agility by 4.5%, and sprints by 3.5%.
- 33 mg/kg helped jumps but not agility or sprints.
- 4At night: no improvement in any test.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Nutrients
Year
2024
Authors
Houda Bougrine, A. Ammar, Atef Salem, Khaled Trabelsi, P. Żmijewski, Haitham A. Jahrami, Hamdi Chtourou, Nizar Souissi
Related Content
Claims (6)
Caffeine improves physical performance more in the morning than in the afternoon because core body temperature starts lower in the morning and rises more after caffeine intake.
For young female handball players who rarely consume caffeine, taking 3 or 6 milligrams of caffeine per kilogram of body weight does not change how hard they feel they are working during intense exercise, no matter whether it is morning or evening.
In young female handball players who rarely consume caffeine, taking 3 or 6 mg of caffeine per kilogram of body weight in the evening does not improve their performance in jumping, sprinting, or agility tests and increases the likelihood of insomnia and headaches.
In young female handball players who rarely consume caffeine, taking a high dose of caffeine in the evening causes more side effects like trouble sleeping, headaches, and fast heart rate than taking the same dose in the morning, even though performance does not change between times of day.
For young female handball players who consume little caffeine, taking 6 mg/kg of caffeine before morning exercise results in greater improvements in jump height, agility, and sprint speed than taking 3 mg/kg, but neither dose improves performance when taken before evening exercise.
In young female handball players who rarely consume caffeine, taking 6 mg of caffeine per kilogram of body weight in the morning improves agility and repeated sprint performance more than taking 3 mg per kilogram, but both doses improve jumping performance equally.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.