Abstract
Studies on muscle activation time in sport after caffeine supplementation confirmed the effectiveness of caffeine. The novel approach was to determine whether a dose of 9 mg/kg/ body mass (b.m.) of caffeine affects the changes of contraction time and the displacement of electrically stimulated muscle (gastrocnemius medialis) in professional athletes who regularly consume products rich in caffeine and do not comply with the caffeine discontinuation period requirements. The study included 40 professional male handball players (age = 23.13 ± 3.51, b.m. = 93.51 ± 15.70 kg, height 191 ± 7.72, BMI = 25.89 ± 3.10). The analysis showed that in the experimental group the values of examined parameters were significantly reduced (p ≤ 0.001) (contraction time: before = 20.60 ± 2.58 ms/ after = 18.43 ± 3.05 ms; maximal displacement: before = 2.32 ± 0.80 mm/after = 1.69 ± 0.51 mm). No significant changes were found in the placebo group. The main achievement of this research was to demonstrate that caffeine at a dose of 9 mg/kg in professional athletes who regularly consume products rich in caffeine has a direct positive effect on the mechanical activity of skeletal muscle stimulated by an electric pulse.
Highlights
Caffeine (1,3,7-trimethylxanthine) is the most frequently consumed stimulant worldwide
It is believed that one of the most important mechanisms of caffeine activity is the direct, antagonistic effect on adenosine receptors [5,6]. This mechanism is based on the prevention of adenosine-induced dopamine release suppression [7,8], which contributes to the stimulation of the body and increased alertness [9]
The mean Tc value decreased significantly, which indicated a reduction in muscle contraction time after the applied dose of caffeine
Summary
Caffeine (1,3,7-trimethylxanthine) is the most frequently consumed stimulant worldwide. The wide distribution of caffeine in the body makes it difficult to precisely determine the individual effects of its activity and its impact on sporting performance [4]. It is believed that one of the most important mechanisms of caffeine activity is the direct, antagonistic effect on adenosine receptors [5,6]. This mechanism is based on the prevention of adenosine-induced dopamine release suppression [7,8], which contributes to the stimulation of the body and increased alertness [9]. There is evidence that caffeine affects phosphodiesterase inhibition, resulting in an increased concentration of cyclic adenosine monophosphate (cAMP), increased catecholamine secretion [8], and inhibition of the γ-aminobutyric acid (GABA) receptors [11]
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