Reproducibility of Acute Caffeine Effect

Reproducibility of the Acute Effect of Caffeine on Energy Metabolism and Muscular Strength, Power and Endurance Performance

Introduction: Various studies have evaluated and verified the ergogenic effect of acute caffeine intake on sports performance, specifically on strength and power performance. However, all experimental investigations designed so far have been based on the comparison of the "caffeine" and "placebo" conditions in a single trial, not considering the reproducibility and variability of caffeine in multiple trials.

Objectives: The present study aims to evaluate the reproducibility and replicability of the acute effect of caffeine intake on energy metabolism and the muscular production of force, power and endurance, according to sex (men vs women) and type of exercise ( bench press vs squat).

Inclusion Criteria:

• Age between ≥ 18 and ≤ 35 years.
• Body Mass Index (BMI) < 25 kg/m².
• Resistance-trained individuals (> 2 years of structured trained).
• Healthy men and women without neurological, cardiometabolic, immunological, or physical conditions that prevent them from exercising.
• Participants must be able to perform the tests described in the following section.

Exclusion Criteria:

• History of neuromuscular diseases, heart diseases, or diseases that may affect liver or muscle metabolism.
• Use of drugs, other stimulants or sport supplements that interfere with the the study dietary supplement.
• Sedentary habits (<150 min/week of moderate exercise).
• Having undergone prolonged periods of forced physical inactivity during the 6 months prior to the study.
• Performing strenuous exercise during the 48 hours prior to the tests.
• Failure to replicate the same food intake on the two days of the experiments.
• Consuming caffeine or any other stimulant after 6 pm the day before the training or tests, to avoid headaches, discomfort, or lethargy among regular caffeine consumers.