-
1.
Preparation and evaluation of caffeine bioadhesive emulgels for cosmetic applications based on formulation design using QbD tools.
de Lafuente, Y, Ochoa-Andrade, A, Parente, ME, Palena, MC, Jimenez-Kairuz, AF
International journal of cosmetic science. 2020;(6):548-556
Abstract
OBJECTIVE The aim of the present study was to evaluate the influence of the incorporation of caffeine as a model active ingredient on the quality attributes of a bioadhesive emulgel formulation previously optimized by Quality by Design (QbD) tools. Emulgels are emerging topical drug delivery systems for cosmetic or pharmaceutical uses, which combine the advantages of both emulsions and gels. METHODS In this work, the observed and predicted values for spreadability, phase separation by centrifugation and detachment forces performed by texturometer were compared with those of the control and active-containing emulgel formulations. In addition, rheological properties, release of caffeine and comparative in vitro/ex vivo bioadhesion properties were evaluated using human skin. RESULTS The flow curves of emulgel formulations showed the typical pseudoplastic and no thixotropic flow with yield stress. The incorporation of active ingredient did not produce significant changes. All emulgels were uniformly spread and no significant differences in spreadability values between control and caffeine containing formulations and neither respect to those predicted values from experimental design optimization were found. Emulgel formulations showed appropriate detachment forces values and no significant differences between caffeine loading and control emulgel formulations were observed. CONCLUSION Caffeine was successfully vehiculized in this optimized bioadhesive emulgel formulation, which showed high robustness regarding the process variability. There were no significant changes in the critical quality attributes after the incorporation of the active ingredient and a promising stability was observed for at least one year. Results suggested that the optimized emulgel is an interesting topical biodhesive delivery system for cosmetic applications, including agents for skin conditioning, not present in gels formulations.
-
2.
Influence of caffeine intake on intravenous adenosine-induced fractional flow reserve.
Kasumi, I, Fujii, K, Satoru, O, Shin, T, Katsuyuki, H, Hiroto, T, Rui, I, Shingo, Y, Sho, N, Wataru, Y, et al
Journal of cardiology. 2020;(5):472-478
Abstract
BACKGROUND This study evaluated whether caffeine abstention is required before fractional flow reserve (FFR) measurement by intravenous adenosine triphosphate (ATP) administration in Japanese patients. METHODS This study was a subanalysis of a previously published study and a total of 208 intermediate lesions that underwent FFR measurements were enrolled for this analysis. Hyperemia was induced by continuous intravenous ATP infusion at 150 μg/kg/min (IVATP150) and 210 μg/kg/min (IVATP210), and by intracoronary administration of nicorandil 2 mg (ICNIC2mg) as a reference standard. RESULTS The degree of change in the FFR value after ICNIC2mg and IVATP210 was similar between the caffeine and non-caffeine groups (0.00 ± 0.02 vs. 0.01 ± 0.02). In patients who consumed caffeine before the FFR measurement, the degree of FFR change was independent of the time interval (<12 h, 12-24 h, and 24-48 h) between caffeine intake and catheterization both after IVATP150 and ICNIC2mg and after IVATP210 and ICNIC2mg. CONCLUSION When compared with the FFR value after ICNIC2mg, the degree of change in the FFR value after IVATP210 were similar regardless of caffeine intake. Strict caffeine abstention before intravenous ATP-induced FFR measurement may not be required in clinical practice.
-
3.
Drugs to Prevent Bronchopulmonary Dysplasia: Effect of Baseline Risk on the Number Needed to Treat.
Jensen, EA, Roberts, RS, Schmidt, B
The Journal of pediatrics. 2020;:244-247
Abstract
Infants born very preterm have a variable baseline risk of bronchopulmonary dysplasia (BPD). Using the example of evidence-based drug therapies to prevent BPD, we designed a visual aid that displays the "number needed to treat" with CIs for caffeine, vitamin A, and hydrocortisone over a range of baseline risks.
-
4.
Effects of caffeine on neuromuscular function in a non-fatigued state and during fatiguing exercise.
Mesquita, RNO, Cronin, NJ, Kyröläinen, H, Hintikka, J, Avela, J
Experimental physiology. 2020;(4):690-706
-
-
Free full text
-
Abstract
NEW FINDINGS What is the central question of the study? What are the effects of caffeine on neuromuscular function in a non-fatigued state and during fatiguing exercise? What is the main finding and its importance? In a non-fatigued state, caffeine decreased the duration of the silent period evoked by transcranial magnetic stimulation. Caffeine-induced reduction of inhibitory mechanisms in the central nervous system before exercise was associated with an increased performance. Individuals who benefit from caffeine ingestion may experience lower perception of effort during exercise and an accelerated recovery of M-wave amplitude postfatigue. This study elucidates the mechanisms of action of caffeine and demonstrates that inter-individual variability of its effects on neuromuscular function is a fruitful area for further work. ABSTRACT Caffeine enhances exercise performance, but its mechanisms of action remain unclear. In this study, we investigated its effects on neuromuscular function in a non-fatigued state and during fatiguing exercise. Eighteen men participated in this randomized, double-blind, placebo-controlled crossover trial. Baseline measures included plantarflexion force, drop jump, squat jump, voluntary activation of triceps surae muscle, soleus muscle contractile properties, M-wave, α-motoneuron excitability (H-reflex), corticospinal excitability, short-interval intracortical inhibition, intracortical facilitation, silent period evoked by transcranial magnetic stimulation (SP) and plasma potassium and caffeine concentrations. Immediately after baseline testing, participants ingested caffeine (6 mg·kg-1 ) or placebo. After a 1-h rest, baseline measures were repeated, followed by a fatiguing stretch-shortening cycle exercise (sets of 40 bilateral rebound jumps on a sledge apparatus) until task failure. Neuromuscular testing was carried out throughout the fatigue protocol and afterwards. Caffeine enhanced drop jump height (by 4.2%) and decreased the SP (by 12.6%) in a non-fatigued state. A caffeine-related decrease in SP and short-interval intracortical inhibition before the fatiguing activity was associated with an increased time to task failure. The participants who benefitted from an improved performance on the caffeine day reported a significantly lower sense of effort during exercise and had an accelerated postexercise recovery of M-wave amplitude. Caffeine modulates inhibitory mechanisms of the CNS, recovery of M-wave amplitude and perception of effort. This study lays the groundwork for future examinations of differences in caffeine-induced neuromuscular changes between those who are deemed to benefit from caffeine ingestion and those who are not.
-
5.
Ergogenic effects of caffeine on peak aerobic cycling power during the menstrual cycle.
Lara, B, Gutiérrez-Hellín, J, García-Bataller, A, Rodríguez-Fernández, P, Romero-Moraleda, B, Del Coso, J
European journal of nutrition. 2020;(6):2525-2534
Abstract
PURPOSE Recent investigations have established that the ingestion of a moderate dose of caffeine (3-6 mg kg-1) can increase exercise and sports performance in women. However, it is unknown whether the ergogenicity of caffeine is similar during all phases of the menstrual cycle. The aim of this investigation was to determine the ergogenic effects of caffeine in three phases of the menstrual cycle. METHODS Thirteen well-trained eumenorrheic triathletes (age = 31 ± 6 years; body mass = 58.6 ± 7.8 kg) participated in a double-blind, cross-over, randomised experimental trial. In the (1) early follicular (EF); (2) preovulation (PO); (3) and mid luteal (ML) phases, participants either ingested a placebo (cellulose) or 3 mg kg-1 of caffeine in an opaque and unidentifiable capsule. After a 60-min wait for substance absorption, participants performed an incremental maximal cycle ergometer test until volitional fatigue (25 W/min) to assess peak aerobic cycling power (Wmax). RESULTS In comparison to the placebo, caffeine increased Wmax in the EF (4.13 ± 0.69 vs. 4.24 ± 0.71 W kg-1, Δ = 2.7 ± 3.3%, P = 0.01), in the PO (4.14 ± 0.70 vs. 4.27 ± 0.73 W kg-1, Δ = 3.3 ± 5.0%; P = 0.03) and in the ML (4.15 ± 0.69 vs. 4.29 ± 0.67 W kg-1, Δ = 3.6 ± 5.1%; P = 0.01) phases. The magnitude of the caffeine ergogenic effect was similar during all of the menstrual cycle phases (P = 0.85). CONCLUSION Caffeine increased peak aerobic cycling power in the early follicular, preovulatory, and mid luteal phases. Thus, the ingestion of 3 mg of caffeine per kg of body mass might be considered an ergogenic aid for eumenorrheic women during all three phases of the menstrual cycle.
-
6.
Infographic. Wake up and smell the coffee: caffeine supplementation and exercise performance.
Grgic, J, Grgic, I, Pickering, C, Schoenfeld, BJ, Bishop, DJ, Virgile, A, Pedisic, Z
British journal of sports medicine. 2020;(5):304-305
-
7.
Caffeine-Containing Energy Shots Cause Acute Impaired Glucoregulation in Adolescents.
Shearer, J, Reimer, RA, Hittel, DS, Gault, MA, Vogel, HJ, Klein, MS
Nutrients. 2020;(12)
Abstract
Caffeine-containing, nutritionally fortified energy shots are consumed at high rates by adolescents, yet little is known about their metabolic impact. The purpose of this study was to examine the consequences of small format, caffeinated energy shots on glucose metabolism and gastrointestinal hormone secretion in adolescents. Twenty participants aged 13-19 years participated in a double-blind, randomized cross-over study consisting of two trials separated by 1-4 weeks. Participants consumed a volume-matched caffeinated energy shot (CAF, 5 mg/kg) or a decaffeinated energy shot (DECAF) followed by a 2 h oral glucose tolerance test. Blood samples were collected and area under the curve (AUC) calculated for glucose, insulin and gut and metabolic hormones. Consumption of CAF resulted in a 25% increase in glucose and a 26% increase in insulin area under the curve (AUC, p = 0.037; p < 0.0001) compared to DECAF. No impact on gut hormones was observed. To further characterize responses, individuals were classified as either slow or fast caffeine metabolizers based on an allele score. Glucose intolerance was greater in genetically fast vs. slow caffeine metabolizers and differences between groups were supported by distinct serum metabolomics separation. Consumption of caffeine-containing energy shots results in acute impaired glucoregulation in healthy adolescents as characterized by hyperinsulinemia following an oral glucose challenge.
-
8.
Effects of caffeine supplementation on physical performance and mood dimensions in elite and trained-recreational athletes.
Jodra, P, Lago-Rodríguez, A, Sánchez-Oliver, AJ, López-Samanes, A, Pérez-López, A, Veiga-Herreros, P, San Juan, AF, Domínguez, R
Journal of the International Society of Sports Nutrition. 2020;(1):2
Abstract
BACKGROUND Caffeine supplementation (CAFF) has an established ergogenic effect on physical performance and the psychological response to exercise. However, few studies have compared the response to CAFF intake among athletes of different competition level. This study compares the acute effects of CAFF on anaerobic performance, mood and perceived effort in elite and moderately-trained recreational athletes. METHODS Participants for this randomized, controlled, crossover study were 8 elite athletes (in the senior boxing national team) and 10 trained-recreational athletes. Under two experimental conditions, CAFF supplementation (6 mg/kg) or placebo (PLAC), the athletes completed a Wingate test. Subjective exertion during the test was recorded as the rating of perceived exertion (RPE) both at the general level (RPEgeneral) and at the levels muscular (RPEmuscular) and cardiorespiratory (RPEcardio). Before the Wingate test, participants completed the questionnaires Profiles of Moods States (POMS) and Subjective Vitality Scale (SVS). RESULTS In response to CAFF intake, improvements were noted in Wpeak (11.22 ± 0.65 vs 10.70 ± 0.84; p = 0.003; [Formula: see text] =0.44), Wavg (8.75 ± 0.55 vs 8.41 0.46; p = 0.001; [Formula: see text] =0.53) and time taken to reach Wpeak (7.56 ± 1.58 vs 9.11 ± 1.53; p < 0.001; [Formula: see text] =0.57) both in the elite and trained-recreational athletes. However, only the elite athletes showed significant increases in tension (+ 325%), vigor (+ 31%) and SVS (+ 28%) scores after the intake of CAFF compared to levels recorded under the condition PLAC (p < 0.05). Similarly, levels of vigor after consuming CAFF were significantly higher in the elite than the trained-recreational athletes (+ 5.8%). CONCLUSIONS CAFF supplementation improved anaerobic performance in both the elite and recreational athletes. However, the ergogenic effect of CAFF on several mood dimensions and subjective vitality was greater in the elite athletes.
-
9.
Caffeine Optimizes HIIT Benefits on Obesity-associated Metabolic Adversity in Women.
Alkhatib, A, Hsieh, MJ, Kuo, CH, Hou, CW
Medicine and science in sports and exercise. 2020;(8):1793-1800
Abstract
PURPOSE We investigated whether obesity adversities such as excessive body fat, compensatory hyperinsulinemia, metabolic endotoxemia, irregular androgenicity, and reduced cardiorespiratory and anaerobic fitness are ameliorated by high-intensity interval training (HIIT) with or without caffeine supplementation in women with obesity. METHODS Twenty-four women with obesity (Asian cutoff point body mass index ≥ 27 kg·m, body fat = 40%) were evenly randomized to caffeine (CAF) and placebo (PLA) trials for an 8-wk HIIT program (10 × 1-min sprints, interspersed by 1-min rest). CAF (3 mg·kg·bw) and PLA were supplemented before each training session. Body fat was assessed by dual-energy x-ray absorptiometry before and after training together with assessments of glucose tolerance (oral glucose tolerance test, or OGTT), lipopolysaccharide endotoxins, testosterone, cardiorespiratory, and anaerobic fitness. RESULTS Significant interaction between HIIT and CAF was found for OGTT glucose and OGTT insulin levels (P = 0.001 and P = 0.049 respectively). HIIT-alone increased glucose at 90 min (P = 0.049) and OGTT insulin at 60 min (P = 0.038). Conversely, HIIT with CAF decreased OGTT glucose at 120 min (P = 0.024) without affecting OGTT insulin. HIIT-alone induced 28.3% higher OGTT insulin (effect size d = 0.59 for area under the curve) and 14.5% higher OGTT glucose (d = 0.28). Conversely, HIIT with CAF decreased OGTT glucose by 19.1% (d = 0.51 for area under the curve) without changing OGTT insulin. HIIT-alone effects on glycemia and insulinemia were concurrent with a 31% increase in lipopolysaccharide endotoxins (P = 0.07; d = 0.78; confidence interval, 5.7-8.7) in the PLA but not in CAF treatment (P = 0.99; d = 0.003; confidence interval, 6.5-10.6), although endotoxin level remained within the recommended healthy thresholds. Furthermore, either HIIT alone or with CAF reduced body fat percentage (P < 0.001, ANOVA main training effects), increased muscle mass (P = 0.002), reduced testosterone (P = 0.005), and increased cardiorespiratory and anaerobic capacity (P < 0.001). CONCLUSIONS HIIT induces fat loss and decreases androgenicity in women with obesity. However, its side effects such as endotoxemia and hyperinsulinemia are ameliorated by caffeine supplementation.
-
10.
The acute effects of thermogenic fitness drink formulas containing 140 mg and 100 mg of caffeine on energy expenditure and fat metabolism at rest and during exercise.
Clark, NW, Wells, AJ, Coker, NA, Goldstein, ER, Herring, CH, Starling-Smith, TM, Varanoske, AN, Panissa, VLG, Stout, JR, Fukuda, DH
Journal of the International Society of Sports Nutrition. 2020;(1):10
Abstract
BACKGROUND Thermogenic fitness drink formulas (TFD) have been shown to increase energy expenditure and markers of lipid metabolism. The purpose of the current study was to compare TFD formulas containing different caffeine concentrations versus a placebo drink on energy expenditure and lipid metabolism at rest and during exercise. METHODS Thirty-two recreationally active participants (22.9 ± 0.7 y, 167.1 ± 1.4 cm, 68.8 ± 2.0 kg, 24.0 ± 1.2% fat) who were regular caffeine consumers, participated in this randomized, double-blind, crossover design study. Participants reported to the laboratory on three occasions, each of which required consumption of either a TFD containing 140 mg or 100 mg of caffeine or a placebo. Baseline measurements of resting energy expenditure (REE) and resting fat oxidation (RFO) were assessed using indirect calorimetry as well as measurements of serum glycerol concentration. Measurements were repeated at 30, 60, 90 min post-ingestion. Following resting measures, participants completed a graded exercise test to determine maximal oxygen uptake (V̇O2max), maximal fat oxidation (MFO) and the exercise intensity that elicits MFO (Fatmax), and total energy expenditure (EE). RESULTS A significant interaction was shown for REE (p < 0.01) and RFO (p < 0.01). Area under the curve analysis showed an increased REE for the 140 mg compared to the 100 mg formula (p = 0.02) and placebo (p < 0.01) and an increased REE for the 100 mg formula compared to placebo (p = 0.02). RFO significantly decreased for caffeinated formulas at 30 min post ingestion compared to placebo and baseline (p < 0.01) and significantly increased for the 140 mg formula at 60 min post-ingestion (p = 0.03). A main effect was shown for serum glycerol concentrations over time (p < 0.01). No significant differences were shown for V̇O2max (p = 0.12), Fatmax (p = 0.22), and MFO (p = 0.05), and EE (p = 0.08) across drinks. CONCLUSIONS Our results suggest that TFD formulas containing 100 and 140 mg of caffeine are effective in increasing REE and that a 40 mg of caffeine difference between the tested formulas may impact REE and RFO in healthy individuals within 60 min of ingestion.