1.
Short-term effect of caffeine on olfactory function in hyposmic patients.
Meusel, T, Albinus, J, Welge-Luessen, A, Hähner, A, Hummel, T
European archives of oto-rhino-laryngology : official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : affiliated with the German Society for Oto-Rhino-Laryngology - Head and Neck Surgery. 2016;(8):2091-5
Abstract
The purpose of this study was to investigate the potential effects of caffeine in patients with olfactory loss. The suggested mechanisms of action consist in the non-selective blocking of adenosine receptors as well as inhibition of the phospodiesterase. Olfactory function was tested twice in 76 hyposmic patients either because of URTI or because of sinunasal causes. For definition of hyposmia and for later assessment of phenyl ethyl alcohol odor threshold, and odor discrimination the Sniffin Sticks data test was used. Using a double-blinded design, the participants were divided into two groups: one received a cup of espresso with caffeine (65 mg/cup), the other a cup of espresso without caffeine (placebo). Before and approximately 45 min after espresso consumption olfactory function was assessed. Across all participants, in comparison to placebo there was no significant effect of caffeine on olfactory function, regardless whether it was caused by an acute infection of the upper respiratory tract or sinunasal disease. These results indicate that-under the current conditions-the phosphodiesterase-inhibitor/adenosine-receptor agonist caffeine has little or no short-term effect on olfactory function in patients with olfactory loss.
2.
Acute effects of caffeine on strength and muscle activation of the elbow flexors.
Trevino, MA, Coburn, JW, Brown, LE, Judelson, DA, Malek, MH
Journal of strength and conditioning research. 2015;(2):513-20
Abstract
The purpose of this study was to examine the effects of caffeine on strength and muscle activation of the elbow flexors. Thirteen recreationally active male volunteers (mean ± SD, age: 21.38 ± 1.26 years) came to the laboratory 4 times. Visit 1 served as a familiarization visit. During visits 2 through 4, subjects ingested a randomly assigned drink, with or without caffeine (0, 5, or 10 mg·kg of body mass), and performed 3 maximal isometric muscle actions of the elbow flexors 60 minutes after ingestion. Maximal strength and rate of torque development (RTD) were recorded. Electromyographic (EMG) and mechanomyographic (MMG) amplitude and frequency, and electromechanical delay (EMD), and phonomechanical delay (PMD) were measured from the biceps brachii. The results indicated that the ingestion of 0 (placebo), 5, or 10 mg·kg of body mass of caffeine did not significantly influence (p > 0.05) peak torque, RTD, normalized EMG amplitude or frequency, normalized MMG amplitude, or EMD and PMD. Normalized MMG frequency was significantly lower (p ≤ 0.05) following ingestion of 5 mg·kg of body mass of caffeine compared with the placebo trial. This was most likely an isolated finding because MMG frequency was the only variable to have a significant difference across all trials. The results suggested that ingestion of either 5 or 10 mg·kg of body mass of caffeine does not provide an ergogenic effect for the elbow flexors during isometric muscle actions.