The Study
Improvements on neuromuscular performance with caffeine ingestion depend on the time-of-day.
This study gave people caffeine or a sugar pill at different times of day and measured how hard they could push during workouts. It found caffeine helped in the morning but not in the evening — but only for these 13 guys who lift weights. It doesn't mean caffeine helps everyone or every kind of exercise.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Caffeine makes you stronger in the morning but not in the afternoon, even though your body absorbs it the same way at both times.
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 548 / 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 — if you train in the morning, caffeine may help you move weights faster; if you train in the afternoon, it won’t help and might make you feel worse.
- 2Caffeine improved squat speed by 5.4–8.1% in the morning at light to medium weights.
- 3No improvement in the afternoon.
- 4More side effects (like jitters) happened in the afternoon.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of science and medicine in sport
Year
2015
Authors
R. Mora‐Rodriguez, J. Pallarés, J. M. López-Gullón, Á. López-Samanes, V. Fernández-Elías, J. Ortega
Related Content
Claims (4)
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.
Taking 6 mg of caffeine per kilogram of body weight one hour before morning squat workouts increases how fast a person can push during squats at moderate to heavy weights, but does not change speed during bench presses or squats done in the afternoon.
In resistance-trained men, consuming caffeine in the afternoon does not increase force production during bench press or squat exercises and occurs with more frequent negative side effects than consuming caffeine in the morning.
In resistance-trained men, drinking caffeine raises blood caffeine levels equally in the morning and afternoon, but body temperature in the ear is lower in the morning than in the afternoon regardless of whether caffeine is consumed.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.