The aim of this study was to investigate the effects of isolated and combined caffeine and sodium bicarbonate consumption on acute isometric mid-thigh pull (IMTP) strength, and verify whether they are cumulative, neutral or subtractive.

Method: Nineteen Sport Sciences Faculty students (Age 23.6±1.6 years, height 171±9.4 cm, weight 64.3±9.6 kg, fat percentage 20.5±7.3 %, BMI 21.7±2.4 kg/m2) participated and completed the intervention. This study was designed as crossover, double-blind and placebo-controlled. Subjects participated under 5 crossover conditions: control (without supplement) (Con), placebo (Pla), caffeine (Caf), sodium bicarbonate (NaHCO3) and caffeine+sodium bicarbonate (Caf+NaHCO3). For Caf conditions, participants consumed 6 mg/kg of caffeine, obtained from dosing the content of 200 mg capsules. As for NaHCO3 conditions, participants consumed 0.3 g/kg of sodium bicarbonate dissolved in water. For the combined condition, (Caf+NaHCO3), intake was set at 6 mg of caffeine and 0.3 g of sodium bicarbonate per kilogram of body weight. All supplements were consumed 60 min before the tests. Two submaximal trials of IMTP were performed at increasing intensities for 5 seconds (approximately %40-60 and %60-80 of their individually perceived 1RM, respectively, with 60-second rest intervals).

Inclusion Criteria:

• Being physically active and healthy
• Did not use ergogenic supplements in the last 3 months
• Did not consume high doses of caffeine (≤120-170 mg/d) were included in this study

Exclusion Criteria:

• Actively using supplements
• Did not perform maximal effort during performance tests
• Not using the supplements in the correct dose or vomiting after use

The data presented in this study are available on website https://osf.io/r6uz2/ with Identifier: 10.17605/OSF.IO/R6UZ2

Supplement preparation, as well as the provision and management of blind conditions for both participants and investigators, were performed by a researcher (Celil KAÇOĞLU) who did not participate in the strength measurements.