Low-Dose of Acute Caffeine Consumption in Coffee Form Do Not Improve Isokinetic Strength Performance

Abstract

Background: Athletes widely consume caffeine to enhance exercise performance due to its potential effects on metabolism and the central nervous system. While moderate-to-high doses of caffeine (>= 5 mg<middle dot>kg(-1)) have been extensively studied, research on the acute impact of low-dose caffeine intake (<= 3 mg<middle dot>kg(-1)), particularly in coffee form, on isokinetic strength performance remains limited. Objective: The current study aimed to examine the acute effects of low-dose caffeine consumption (1.5 mg<middle dot>kg(-1) and 3 mg<middle dot>kg(-1)) in coffee form on isokinetic knee strength performance in physically active males. Methods: Thirteen physically active male university students (age: 20.75 +/- 0.96 years; height: 177.08 +/- 4.07 cm; body mass: 69.91 +/- 5.56 kg) participated in a double-blind, randomized, crossover study. Participants consumed either 1.5 mg<middle dot>kg(-1) or 3 mg<middle dot>kg(-1) of caffeine in coffee form or a placebo (decaffeinated coffee) 60 min before testing attempts. Single-leg isokinetic knee strength was assessed at two angular velocities (60 degrees/s and 180 degrees/s) using an IsoMed 2000 dynamometer. Peak moment, total work, and rate of perceived exertion (RPE) were recorded and analyzed. Results: No statistically significant differences were observed between the caffeine and placebo conditions in terms of peak moment or total work at either angular velocity (p > 0.05). Effect sizes were small ( eta(2) < 0.06) for all isokinetic strength parameters at both 60 degrees/s and 180 degrees/s. Additionally, RPE values did not significantly differ between conditions, suggesting that low-dose caffeine intake did not influence perceived exertion. Conclusion: Acute low-dose caffeine supplementation in coffee form does not significantly enhance isokinetic knee strength or alter perceived exertion in physically active males.