scholarly journals Effects of caffeine ingestion on dynamic visual acuity: a placebo-controlled, double-blind, balanced-crossover study in low caffeine consumers

2021 ◽  
Author(s):  
Beatríz Redondo ◽  
Raimundo Jiménez ◽  
Rubén Molina ◽  
Kristine Dalton ◽  
Jesús Vera
Keyword(s):  
Visual Acuity ◽  
Crossover Study ◽  
Random Order ◽  
Random Motion ◽  
Caffeine Intake ◽  
Moving Targets ◽  
Dynamic Visual Acuity ◽  
Double Blind ◽  
Caffeine Ingestion ◽  
Motion Paths

Abstract Background Acute caffeine ingestion has been associated with improvements in cognitive performance and visual functioning. The main objective of this study was to determine the effects of caffeine intake on dynamic visual acuity (DVA). Methods Twenty-one low caffeine consumers (22.5 ± 1.6 years) took part in this placebo-controlled, double-blind, and balanced crossover study. In two different days and following a random order, participants ingested either caffeine (4 mg/kg) or placebo, and DVA was measured after 60 min of ingesting the corresponding capsule. A recently developed and validated software (moV& test, V&mp Vision Suite, Waterloo, Canada) was used to assess DVA. Results We found a greater accuracy for both the horizontal and random motion paths of DVA after caffeine ingestion (p < 0.001 and p = 0.002, respectively). In regard to the speed of the response, our data revealed that caffeine intake was associated with a faster reaction time for horizontally (p = 0.012) but not for randomly (p = 0.846) moving targets. Also, participants reported higher levels of perceived activation after consuming caffeine in comparison to placebo (p < 0.001). Conclusions Our data suggest that caffeine intake (i.e., a capsule containing 4 mg/kg) has an ergogenic effect on DVA, which may be of special relevance in real-word contexts that require to accurately and rapidly detect moving targets (e.g., sports, driving, or piloting).

Cortical substrates of the effects of caffeine and time-on-task on perception of effort

2014 ◽  
Vol 117 (12) ◽  
pp. 1514-1523 ◽  
Author(s):  
Helma M. de Morree ◽  
Christoph Klein ◽  
Samuele M. Marcora
Keyword(s):  
Vastus Lateralis ◽  
Knee Extension ◽  
Caffeine Intake ◽  
Time On Task ◽  
Force Output ◽  
Double Blind ◽  
Caffeine Ingestion ◽  
Perceived Effort ◽  
Perception Of Effort ◽  
Motor Areas

Caffeine intake results in a decrease in perception of effort, but the cortical substrates of this perceptual effect of caffeine are unknown. The aim of this randomized counterbalanced double-blind crossover study was to investigate the effect of caffeine on the motor-related cortical potential (MRCP) and its relationship with rating of perceived effort (RPE). We also investigated whether MRCP is associated with the increase in RPE occurring over time during submaximal exercise. Twelve healthy female volunteers performed 100 intermittent isometric knee extensions at 61 ± 5% of their maximal torque 1.5 h after either caffeine (6 mg/kg) or placebo ingestion, while RPE, vastus lateralis electromyogram (EMG), and MRCP were recorded. RPE and MRCP amplitude at the vertex during the first contraction epoch (0–1 s) were significantly lower after caffeine ingestion compared with placebo ( P < 0.05) and were significantly higher during the second half of the submaximal intermittent isometric knee-extension protocol compared with the first half ( P < 0.05). No significant effects of caffeine and time-on-task were found for EMG amplitude and submaximal force output variables. The covariation between MRCP and RPE across both caffeine and time-on-task ( r10 = −0.335, P < 0.05) provides evidence in favor of the theory that perception of effort arises from neurocognitive processing of corollary discharges from premotor and motor areas of the cortex. Caffeine seems to reduce perception of effort through a reduction in the activity of cortical premotor and motor areas necessary to produce a submaximal force, and time-on-task has the opposite effect.

A Comparison between Methods for Assessing the Resolution of Moving Targets (Dynamic Visual Acuity)

Perception ◽  
1996 ◽  
Vol 25 (12) ◽  
pp. 1389-1399 ◽  
Author(s):  
Gerald M Long ◽  
Dawn M Johnson
Keyword(s):  
Visual Acuity ◽  
Target Duration ◽  
Target Velocity ◽  
Channel Activity ◽  
Moving Targets ◽  
Dynamic Visual Acuity ◽  
Dependent Variables ◽  
Two Measures ◽  
Future Work

A comparison was made between two measures of visual functioning in a dynamic context that required the resolution of moving targets. Performance obtained on a traditional task of dynamic visual acuity, which involves the determination of the smallest target that can be resolved at a given target velocity, was compared with that obtained with an alternative task that essentially reverses the independent and dependent variables. Generally similar patterns of results were obtained across the two procedures, but the alternative procedure appears to offer several advantages such as greater ease of administration, improved precision of measurement, and more-direct assessment of underlying channel activity. The recommended use of the new procedure in future work involving dynamic acuity as well as particular variables that should be carefully controlled in such work (eg target duration and target size) are discussed.

Dose Effect of Caffeine on Testosterone and Cortisol Responses to Resistance Exercise

2008 ◽  
Vol 18 (2) ◽  
pp. 131-141 ◽  
Author(s):  
C. Martyn Beaven ◽  
Will G. Hopkins ◽  
Kier T. Hansen ◽  
Matthew R. Wood ◽  
John B. Cronin ◽  
...  
Keyword(s):  
Resistance Exercise ◽  
Random Order ◽  
Acute Effect ◽  
Rugby League ◽  
Dose Effect ◽  
Exercise Session ◽  
Dependent Manner ◽  
Double Blind ◽  
Caffeine Ingestion ◽  
Testosterone Concentration

Introduction:Interest in the use of caffeine as an ergogenic aid has increased since the International Olympic Committee lifted the partial ban on its use. Caffeine has beneficial effects on various aspects of athletic performance, but its effects on training have been neglected.Purpose:To investigate the acute effect of caffeine on the exercise-associated increases in testosterone and cortisol in a double-blind crossover study.Methods:Twenty-four professional rugby-league players ingested caffeine doses of 0, 200, 400, and 800 mg in random order 1 hr before a resistance-exercise session. Saliva was sampled at the time of caffeine ingestion, at 15-min intervals throughout each session, and 15 and 30 min after the session. Data were log-transformed to estimate percent effects with mixed modeling, and effects were standardized to assess magnitudes.Results:Testosterone concentration showed a small increase of 15% (90% confidence limits, ± 19%) during exercise. Caffeine raised this concentration in a dose-dependent manner by a further small 21% (± 24%) at the highest dose. The 800-mg dose also produced a moderate 52% (± 44%) increase in cortisol. The effect of caffeine on the testosterone:cortisol ratio was a small decline (14%; ± 21%).Conclusion:Caffeine has some potential to benefit training outcomes via the anabolic effects of the increase in testosterone concentration, but this benefit might be counteracted by the opposing catabolic effects of the increase in cortisol and resultant decline in the testosterone:cortisol ratio.

Training Effects on the Resolution of Moving Targets—Dynamic Visual Acuity

1989 ◽  
Vol 31 (4) ◽  
pp. 443-451 ◽  
Author(s):  
Gerald M. Long ◽  
David A. Rourke
Keyword(s):  
Visual Acuity ◽  
Test Session ◽  
Moving Targets ◽  
Dynamic Visual Acuity ◽  
Training Effects ◽  
Final Test ◽  
Male College

In initial 60-min sessions, the dynamic visual acuity (DVA)of 54 male college observers was determined over a range of target velocities (60, 90, 120, and 150 deg/s) at each of three durations (200, 400, and 600 ms). Following four 30-min practice sessions with the task, a final test session identical to the first was then conducted. Highly significant training effects on DVA were obtained; contrary to previous work, these effects were most marked for observers with initially poorer performance.

(Ab)normal saline and physiological Hartmann's solution: a randomized double-blind crossover study

2002 ◽  
Vol 104 (1) ◽  
pp. 17-24 ◽  
Author(s):  
Fiona REID ◽  
Dileep N. LOBO ◽  
Robert N. WILLIAMS ◽  
Brian J. ROWLANDS ◽  
Simon P. ALLISON
Keyword(s):  
Body Weight ◽  
Serum Albumin ◽  
Crossover Study ◽  
Random Order ◽  
Serum Biochemistry ◽  
Sodium Content ◽  
Plasma Volume Expansion ◽  
Double Blind ◽  
Blind Crossover Study ◽  
Double Blind Crossover Study

In this double-blind crossover study, the effects of bolus infusions of 0.9% saline (NaCl) and Hartmann's solution on serum albumin, haematocrit and serum and urinary biochemistry were compared in healthy subjects. Nine young adult male volunteers received 2-litre intravenous infusions of 0.9% saline and Hartmann's solution on separate occasions, in random order, each over 1h. Body weight, haematocrit and serum biochemistry were measured pre-infusion and at 1h intervals for 6h. Biochemical analysis was performed on pooled post-infusion urine. Blood and plasma volume expansion, estimated by dilutional effects on haematocrit and serum albumin, were greater and more sustained after saline than after Hartmann's solution (P<0.01). At 6h, body weight measurements suggested that 56% of the infused saline was retained, in contrast with only 30% of the Hartmann's solution. Subjects voided more urine (median: 1000 compared with 450ml) of higher sodium content (median: 122 compared with 73mmol) after Hartmann's than after saline (both P = 0.049), despite the greater sodium content of the latter. The time to first micturition was less after Hartmann's than after saline (median: 70 compared with 185min; P = 0.008). There were no significant differences between the effects of the two solutions on serum sodium, potassium, urea or osmolality. After saline, all subjects developed hyperchloraemia (>105mmol/l), which was sustained for >6h, while serum chloride concentrations remained normal after Hartmann's (P<0.001 for difference between infusions). Serum bicarbonate concentration was significantly lower after saline than after Hartmann's (P = 0.008). Thus excretion of both water and sodium is slower after a 2-litre intravenous bolus of 0.9% saline than after Hartmann's solution, due possibly to the more physiological [Na+]/[Cl-] ratio in Hartmann's solution (1.18:1) than in saline (1:1) and to the hyperchloraemia caused by saline.

Effects of caffeine ingestion on upper and lower limb muscle power of handball players: a double-blind, placebo-controlled, crossover study

2021 ◽  
Author(s):  
Julio Cesar Correia Rocha ◽  
André Luiz Silva da Rocha ◽  
Gutemberg da Silva Santos Soares ◽  
Carlos Rafaell Correia-Oliveira
Keyword(s):  
Crossover Study ◽  
Lower Limb ◽  
Muscle Power ◽  
Lower Limb Muscle ◽  
Limb Muscle ◽  
Double Blind ◽  
Caffeine Ingestion ◽  
Double Blind Placebo

Enhancement of High-Intensity Actions and Physical Performance During a Simulated Brazilian Jiu-Jitsu Competition With a Moderate Dose of Caffeine

2016 ◽  
Vol 11 (7) ◽  
pp. 861-867 ◽  
Author(s):  
Francisco Javier Diaz-Lara ◽  
Juan del Coso ◽  
Javier Portillo ◽  
Francisco Areces ◽  
Jose Manuel García ◽  
...  
Keyword(s):  
Blood Lactate ◽  
Physical Performance ◽  
Bench Press ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Random Order ◽  
Moderate Dose ◽  
Double Blind ◽  
Caffeine Ingestion ◽  
Physical Tests

Context:Although caffeine is one of the most commonly used substances in combat sports, information about its ergogenic effects on these disciplines is very limited.Purpose:To determine the effectiveness of ingesting a moderate dose of caffeine to enhance overall performance during a simulated Brazilian jiu-jitsu (BJJ) competition.Methods:Fourteen elite BJJ athletes participated in a double-blind, placebo-controlled experimental design. In a random order, the athletes ingested either 3 mg/kg body mass of caffeine or a placebo (cellulose, 0 mg/kg) and performed 2 simulated BJJ combats (with 20 min rest between them), following official BJJ rules. Specific physical tests such as maximal handgrip dynamometry, maximal height during a countermovement jump, permanence during a maximal static-lift test, peak power in a bench-press exercise, and blood lactate concentration were measured at 3 specific times: before the first combat and immediately after the first and second combats. The combats were video-recorded to analyze fight actions.Results:After the caffeine ingestion, participants spent more time in offensive actions in both combats and revealed higher blood lactate values (P < .05). Performance in all physical tests carried out before the first combat was enhanced with caffeine (P < .05), and some improvements remained after the first combat (eg, maximal static-lift test and bench-press exercise; P < .05). After the second combat, the values in all physical tests were similar between caffeine and placebo.Conclusions:Caffeine might be an effective ergogenic aid for improving intensity and physical performance during successive elite BJJ combats.

The Effects of Target Borders on Dynamic Visual Acuity: Practical and Theoretical Implications

Perception ◽  
1988 ◽  
Vol 17 (6) ◽  
pp. 745-751 ◽  
Author(s):  
Gerald M Long ◽  
Philip M Garvey
Keyword(s):  
Visual Acuity ◽  
Spatial Frequency ◽  
Frequency Component ◽  
Neural Mechanisms ◽  
Moving Targets ◽  
Dynamic Visual Acuity ◽  
Stimulus Energy ◽  
Spatial Frequency Component ◽  
Slow Moving ◽  
Practical Implications

The effects of target borders on the ability of observers to resolve moving targets (Landolt Cs) under a range of conditions were examined. Contrary to reported findings with stationary targets, it was predicted that the presence of borders would improve acuity for slow-moving targets because (i) overall stimulus energy is kept relatively constant as target detail varies, and (ii) a low-spatial-frequency component is held constant as target detail varies. In an experiment in which a two-sided border (above and below the target) was used, the predicted beneficial effect of the border at slow speeds was obtained. The results are discussed in terms of practical implications for the assessment of dynamic visual acuity as well as the potential neural mechanisms underlying performance.

Dilution and redistribution effects of rapid 2-litre infusions of 0.9% (w/v) saline and 5% (w/v) dextrose on haematological parameters and serum biochemistry in normal subjects: a double-blind crossover study

2001 ◽  
Vol 101 (2) ◽  
pp. 173-179 ◽  
Author(s):  
Dileep N. LOBO ◽  
Zeno STANGA ◽  
J.Alastair D SIMPSON ◽  
John A. ANDERSON ◽  
Brian J. ROWLANDS ◽  
...  
Keyword(s):  
Serum Albumin ◽  
Crossover Study ◽  
Bioelectrical Impedance ◽  
Random Order ◽  
Normal Subjects ◽  
Albumin Concentration ◽  
Serum Albumin Concentration ◽  
Double Blind ◽  
Blind Crossover Study ◽  
Double Blind Crossover Study

Although hypoalbuminaemia after injury may result from increased vascular permeability, dilution secondary to crystalloid infusions may contribute significantly. In this double-blind crossover study, the effects of bolus infusions of crystalloids on serum albumin, haematocrit, serum and urinary biochemistry and bioelectrical impedance analysis were measured in healthy subjects. Ten male volunteers received 2-litre infusions of 0.9% (w/v) saline or 5% (w/v) dextrose over 1 h; infusions were carried out on separate occasions, in random order. Weight, haemoglobin, serum albumin, serum and urinary biochemistry and bioelectrical impedance were measured pre-infusion and hourly for 6 h. The serum albumin concentration fell in all subjects (20% after saline; 16% after dextrose) by more than could be explained by dilution alone. This fall lasted more than 6 h after saline infusion, but values had returned to baseline 1 h after the end of the dextrose infusion. Changes in haematocrit and haemoglobin were less pronounced (7.5% after saline; 6.5% after dextrose). Whereas all the water from dextrose was excreted by 2 h after completion of the infusion, only one-third of the sodium and water from the saline had been excreted by 6 h, explaining its persistent diluting effect. Impedances rose after dextrose and fell after saline (P < 0.001). Subjects voided more urine (means 1663 and 563 ml respectively) of lower osmolality (means 129 and 630 mOsm/kg respectively) and sodium content (means 26 and 95 mmol respectively) after dextrose than after saline (P < 0.001). While an excess water load is excreted rapidly, an excess sodium load is excreted very slowly, even in normal subjects, and causes persistent dilution of haematocrit and serum albumin. The greater than expected change in serum albumin concentration when compared with that of haemoglobin suggests that, while dilution is responsible for the latter, redistribution also has a role in the former. Changes in bioelectrical impedance may reflect the electrolyte content rather than the volume of the infusate, and may be unreliable for clinical purposes.

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