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·kg⁻¹) have been extensively studied, research on the acute impact of low-dose caffeine intake (≤3 mg·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·kg⁻¹ and 3 mg·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·kg⁻¹ or 3 mg·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°/s and 180°/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°/s and 180°/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.