Effects of different doses of caffeine on cognitive performance in healthy physically active individuals

PURPOSE

Caffeine is a potent central nervous system stimulant that increases the activity of the prefrontal cortex and can improve various cognitive skills. An improvement in these cognitive skills can lead to further benefits in athletic performance. Therefore, it is necessary to clarify the dose-response of caffeine on cognitive performance. This study aimed to determine the effects of different doses of caffeine on sport-related cognitive aspects.

METHODS

Twenty-nine healthy physically active young adults were recruited. All participants completed three trials under the following conditions: (a) placebo, (b) 3 mg/kg, or (c) 6 mg/kg body mass of caffeine. In each trial, different cognitive abilities were evaluated with the following battery of tests: reaction time (Dynavision™ D2), anticipation (Bassin Anticipation Timer), sustained attention (Go/No-Go and Eriksen Flanker Test) and memory tests. Moreover, the side effects and the perceived sensation index were recorded 24 h after each test.

RESULTS

Reaction time only improved following 6 mg/kg of caffeine intake (Physical reaction time: -0.04 s, 95% CI -0.08 to -0.01 s, P = 0.036, d = 0.5; Motor reaction time: -0.04 s, 95% CI -0.07 to -0.01 s, P = 0.008, d = 0.6) compared to the placebo condition. Anticipation, sustained attention, and memory were not affected after either caffeine dose intake (all P > 0.05). In addition, the 6 mg/kg dose of caffeine augmented the occurrence of the side effects of increased activeness (P = 0.046) and nervousness (P = 0.001).

CONCLUSION

Acute intake of 6 mg/kg caffeine is effective in improving reaction time despite increasing the occurrence of side effects in healthy physically active young adults.

STUDY REGISTRATION

This study has been registered in ClinicalTrials whose ID is: NCT05995314 (2023-08-08).

Neurobehavioral measures of coincidence anticipation timing

Coincidence anticipation (CA) refers to the ability to coordinate responses to the arrival of a moving object. This study investigates the neurobehavioral processes that underlie CA through the measurement of electroencephalography (EEG) recorded during a CA task on a 17-foot plastic rail with evenly spaced LED lights. Participants responded at the anticipated moment a sequence of successively lit LEDs coincided with a stationary target. Healthy young adult participants (Mage = 21) performed six blocks with movement at 20, 30, or 40 mph and the direction either inbound or outbound relative to the participant. Behavioral results demonstrated a main effect of speed and an interaction between speed and direction, with outbound motion producing early responses and inbound motion producing delayed responses that increased at greater speeds. EEG demonstrated characteristic P1, N2, and P3-like visual evoked potentials (VEPs). VEP amplitudes revealed a significant direction by channel interaction for the P1, indicative of more medial responses for inbound motion. Significant laterality differences were present in the N2, whereas the P3 component produced significant main effects and interactions of speed and direction. This novel combination of three-dimensional CA with EEG demonstrates systematic brain responses that are tuned for motion speed and sensitive to different egocentric motion patterns thereby shedding new light on the mechanism of human visual-motor control.

Topical Review: Visual Performance Assessments for Sport

SIGNIFICANCE

Eye care professionals seek to provide effective vision care for a variety of patient needs, including performance in sports and recreational pursuits. This review provides an analysis of common visual performance assessments, including summaries of recent clinical research from a diverse array of professional literature.Vision is recognized as an important element of sports performance. Elite athletes frequently demonstrate exceptional abilities to see and respond effectively in sports competition. Which visual factors are important and how to most effectively assess visual performance are the sources of much debate. This topical review presents an evidence-based review of the common visual performance factors assessed in athletes, beginning with guidance for conducting a visual task analysis for the variety of sports that athlete patients may compete in. An information processing model is used to provide a framework for understanding the contributions of the many visual performance factors used during sports.

Effects of exercise intensity on anticipation timing performance during a cycling task at moderate and vigorous intensities in children aged 7-11 years

This study examined coincidence anticipation timing performance at moderate and fast stimulus speeds before, during, and after a 15 minute cycling task. In a within-subject design, 24 children (18 males and 6 females) exercised on a cycle ergometer under two experimental conditions: exercise intensities of 50% (moderate) and 75% (vigorous) heart rate reserve. Coincidence anticipation timing was measured using the Bassin Anticipation Timer at stimulus speeds of 5 and 8 mph. A 2 (intensity) × 3 (time) repeated measures ANOVA was conducted to evaluate the effect of exercise intensity on coincidence anticipation performance before, during, and immediately after the cycling task. Results indicated that for absolute error there was no significant main effect for time (p = .633) or experimental condition (p = .782) at the 5 mph stimulus speed. However, there was a significant interaction effect between experimental condition and time (p = 0.026) at the 5 mph stimulus speed. At the 8 mph stimulus speed, there was no significant main effect for time (p = .910) or condition (p = .938), or interaction effect between experimental condition and time (p = .591). Cycling exercise at moderate intensity appears to influence anticipation timing performance during and immediately after exercise in children, but only when stimulus speeds are moderate in nature.

Schizotypal traits and forearm motor control against self-other produced action in a bimanual unloading task

The present study investigated the relation between schizotypy and motor control against self- or other-produced action. We used an unloading task to focus on the timing component of anticipatory motor control. In the task, a weight was removed from a participants' hand by the participants themselves or by an experimenter (voluntary versus imposed unloading). Postural disturbance at the removal timing was measured as an index of predictive function in motor control. We hypothesized that the postural disturbance in the voluntary unloading would be positively related to schizotypal traits; however, the results did not support this theory. The results showed almost zero correlation between the schizotypy scores and the postural disturbance in the voluntary unloading condition. In contrast, the schizotypy scores positively correlated with the postural disturbance in the imposed unloading condition. These findings were replicated across two participant groups and two schizotypy scales. Further analyses on subscales of the schizotypy questionnaire found moderate levels of positive correlation between each subscale for Cognitive-Perceptual and Disorganization factors and the disturbance. Accordingly, the present study did not support the idea that non-pathological individuals with high schizotypal traits have deficits in prediction of self-produced actions, at least for a temporal domain. Instead, the results suggested that individuals with high schizotypal traits, particularly for the positive and disorganization symptoms, are not good at responding to others-produced actions. The schizophrenic symptoms were discussed in terms of the failure in the processes executed after calculating prediction of sensory consequences and dysfunction in internal models for "other people".

Mapping Time-to-Contact and Time-to-Peak Effector Velocity in Interceptive Striking Tasks

PURPOSE

This study investigated perception and action coupling as reflected in a mapping between time-to-contact (TTC) and time-to-peak-velocity (TPV) for children and youths aged 7 to 8, 11 to 12, and 15 to 16 years old and adults aged 19 to 20 years old performing a task that allowed the participants to self-select the interception position in a baseball-like batting game on a graphics tablet.

METHOD

The moving object to be hit for distance had curvilinear trajectories toward the hitter that were determined by simulated weightings of gravity and velocity.

RESULTS

Successful interceptions in all age groups were characterized by a mapping of mean TTC and TPV and a higher correlation of these variables with increasing age. The object was hit at approximately 90% TPV so that the implement was still accelerating on contact-an adaptive task feature for a striking distance criterion.

CONCLUSION

The results are consistent with theories of perception-action coupling that are congruent with the ecological and dynamical approaches to action where TTC, a source of environmental information, is mapped relative to TPV, largely independent of the particular kinematic task demands of the approaching object. The organization of the coupling of TTC prior to TPV was evident across all age groups and is evidence for a common strategy for this type of interceptive action. The age-related changes in the strength of the relationship between TTC and TPV are evidence of increased sensitivity to the coupling between TTC and TPV.

Coincidence Anticipation Timing Performance during an Acute Bout of Brisk Walking in Older Adults: Effect of Stimulus Speed

This study examined coincidence anticipation timing (CAT) performance at slow and fast stimulus speeds before, during, and after an acute bout of walking in adults aged 60–76 years. Results from a series of repeated measures ANOVAs indicated significant rest versus exercise × stimulus speed × time interactions for absolute and variable errors (both P = 0.0001) whereby absolute and variable error scores, when stimulus speed was slow, improved as the duration of exercise increased. When stimulus speed was fast there were significantly greater absolute and variable errors at 18 minutes of the walking bout. There was also greater error at 18 minutes during walking compared to rest. These results suggest that, in a task involving walking and CAT, stimulus speeds plays an important role; specifically walking (exercise) enhances CAT performance at slow stimulus speeds but reduces CAT performance at fast stimulus speeds. The implications are that in everyday situations, where events require dual-task responses to be made at different speeds, for example, walking on the pavement whilst avoiding a crowd, compared to crossing a busy road, an understanding of how different stimulus speeds influence dual-task performance is extremely important, particularly in the older adult population.

Young Women do it Better: Sexual Dimorphism in Temporal Discrimination

The temporal discrimination threshold (TDT) is the shortest time interval at which two sensory stimuli presented sequentially are detected as asynchronous by the observer. TDTs are known to increase with age. Having previously observed shorter thresholds in young women than in men, in this work we sought to systematically examine the effect of sex and age on temporal discrimination. The aims of this study were to examine, in a large group of men and women aged 20–65 years, the distribution of TDTs with an analysis of the individual participant’s responses, assessing the “point of subjective equality” and the “just noticeable difference” (JND). These respectively assess sensitivity and accuracy of an individual’s response. In 175 participants (88 women) aged 20–65 years, temporal discrimination was faster in women than in men under the age of 40 years by a mean of approximately 13 ms. However, age-related decline in temporal discrimination was three times faster in women so that, in the age group of 40–65 years, the female superiority was reversed. The point of subjective equality showed a similar advantage in younger women and more marked age-related decline in women than men, as the TDT. JND values declined equally in both sexes, showing no sexual dimorphism. This observed sexual dimorphism in temporal discrimination is important for both (a) future clinical research assessing disordered mid-brain covert attention in basal-ganglia disorders, and (b) understanding the biology of this sexual dimorphism which may be genetic or hormonal.

Assessment of the ergogenic effect of caffeine supplementation on mood, anticipation timing, and muscular strength in older adults

The effect of caffeine to promote improvements in mood, cognition, and exercise performance has been well established in young and athletic adults. However, little is known about whether such nutritional ergogenic aids are effective in enhancing psychological well-being, physiological or cognitive performance in older adults. This study assesses the ergogenic effect of caffeine on mood, perceptual-motor coupling, and muscular strength in an older human population. Following a familiarization session, 12 apparently healthy volunteers (nine females and three males; 69 ± 6 years) completed two laboratory visits. “Pre ingestion” trials of mood state Brunel Mood State Inventory (BRUMS) and coincidence anticipation performance (Bassin anticipation timer) at slow (3 mph) and fast (8 mph) stimulus speeds were completed on both visits. Using a randomized, double-blind, cross-over design, participants consumed either caffeine (3 mg/kg body mass) or a placebo. Sixty minutes postingestion participants repeated the trials before completing a set of 10 consecutive repetitions of maximal knee extension using isokinetic dynamometry. Rating of perceived exertion (RPE) was assessed following the fifth and final repetition. Caffeine ingestion significantly improved mood state scores for vigor by 17% (P = 0.009) and reduced absolute error by 35% (P = 0.045) during coincidence anticipation assessment at 8 mph compared to placebo. There were no other significant effects. Caffeine ingestion failed to augment maximal voluntary contraction of the knee extensors and RPE did not prove to be significantly different to from placebo (P > 0.33 in each case). Acute caffeine ingestion may not be an effective ergogenic aid for improving muscular strength in older adults but could possibly be used as a nutrition supplement for enhancing mood and improving cognitive performance in daily living tasks where interceptive timing skills are required.

Development of Coincidence-Anticipation Timing in a Catching Task

This study examined the effects of age, target location, and stimulus speed on coincidence-anticipation timing in a catching task. Males aged 11 to 18 years made simulated catching movements toward a light stimulus that rapidly approached the head or chest at various speeds. Coincidence-anticipation timing accuracy, movement onset times, and movement times did not differ by age. However, 17- to 18-year-olds exhibited significantly faster movement speeds than 14- to 16-year-olds. Target location (head or chest) did not affect coincidence-anticipation timing accuracy or movement speed. However, movements toward the head were initiated earlier and took longer than movements to the chest. Finally, stimulus speed had statistically significant effects on all measures: faster stimuli were associated with longer delays in coincidence-anticipation timing responses, earlier movement onset times, shorter movement times, and faster movement speeds. These results underscore the adaptability of coincidence-anticipation timing abilities for responding to stimuli under varying temporal and spatial constraints.

Children's age-related speed-accuracy strategies in intercepting moving targets in two dimensions

PURPOSE

This study investigated the age-related speed-accuracy strategies of children, adolescents, and adults in performing a rapid striking task that allowed the self-selection of the interception position in a virtual, two-dimensional environment.

METHOD

The moving target had curvilinear trajectories that were determined by combinations of simulated weightings of gravity and velocity. Mass and coefficient of restitution were also assigned to the target to encourage interception with maximal effector velocity. The performance outcome was the measure of the distance that the target traveled following interception that was the result of the effector velocity and angle of motion at the time that the target was struck.

RESULTS

The number of accurate interceptions increased linearly with age. Younger children hit the object at a slower velocity and had longer response latency and movement times compared with older age groups. Effector velocity at contact was shown to be parabolic and reached an asymptote for older children and adolescents followed by a decrease in effector velocity at contact among the adults, although horizontal effector displacement increased linearly with age.

CONCLUSIONS

The increased effector displacement and the asymptotic/parabolic trend for effector velocity at contact with age reveals an age-related speed-accuracy trade-off in this interception task. The age limitations appear more related to the reduced capacity to predict the spatial-temporal properties of the target trajectory than do age-related limitations in the speed of information processing.

Coincidence-anticipation timing requirements are different in racket sports

The aim of this study was to compare the coincidence-anticipation timing accuracy of athletes of different racket sports with various stimulus velocity requirements. Ninety players (15 girls, 15 boys for each sport) from tennis (M age = 12.4 yr., SD = 1.4), badminton (M age = 12.5 yr., SD = 1.4), and table tennis (M age = 12.4 yr., SD = 1.2) participated in this study. Three different stimulus velocities, low, moderate, and high, were used to simulate the velocity requirements of these racket sports. Tennis players had higher accuracy when they performed under the low stimulus velocity compared to badminton and table tennis players. Badminton players performed better under the moderate speed comparing to tennis and table tennis players. Table tennis players had better performance than tennis and badminton players under the high stimulus velocity. Therefore, visual and motor systems of players from different racket sports may adapt to a stimulus velocity in coincidence-anticipation timing, which is specific to each type of racket sports.

Sex differences in motor and cognitive abilities predicted from human evolutionary history with some implications for models of the visual system

This article expands the knowledge base available to sex researchers by reviewing recent evidence for sex differences in coincidence-anticipation timing (CAT), motor control with the hand and arm, and visual processing of stimuli in near and far space. In CAT, the differences are between sex and, therefore, typical of other widely reported sex differences. Men perform CAT tasks with greater accuracy and precision than women, who tend to underestimate time to arrival. Null findings arise because significant sex differences are found with easy but not with difficult tasks. The differences in motor control and visual processing are within sex, and they underlie reciprocal patterns of performance in women and men. Motor control is exerted better by women with the hand than the arm. In contrast, men showed the reverse pattern. Visual processing is performed better by women with stimuli within hand reach (near space) as opposed to beyond hand reach (far space); men showed the reverse pattern. The sex differences seen in each of these three abilities are consistent with the evolutionary selection of men for hunting-related skills and women for gathering-related skills. The implications of the sex differences in visual processing for two visual system models of human vision are discussed.

The effect of exercise intensity on coincidence anticipation performance at different stimulus speeds

The aim of this study was to examine the effect of exercise intensity on coincidence anticipation timing [CAT] performance at different stimulus speeds. Fourteen young adults (11 males and 3 females) volunteered to participate in the study following ethical approval. After familiarisation, coincidence anticipation was measured using the Bassin Anticipation Timer under three conditions: rest, moderate-intensity and high-intensity exercise with stimulus speeds of 3, 5 and 8 mph, set using an incremental running protocol until the participants reached a steady state of 70% and 90% of heart rate reserve (HRR), respectively. Results indicated a significant exercise intensity × stimulus speed interaction (p=0.0001) for absolute error (AE). There were no significant differences in AE across exercise intensities at a stimulus speed of 3 mph (p>0.05). AE was poorer during high-intensity exercise (90% HRR) compared to rest (p=0.022), and moderate-intensity (70% HRR) exercise (all, p=0.004 or better) at 5 and 8 mph. Variable error (VE) was similar across exercise intensities at stimulus speeds of both 3 and 5 mph (p>0.05). At a stimulus speed of 8 mph, VE was significantly poorer during high-intensity exercise compared to rest (p=0.006) and moderate-intensity exercise (p=0.008). There were no significant differences for constant error (p>0.05) across exercise intensities or stimulus speeds. High-intensity exercise is associated with poorer CAT performance. However, stimulus speed plays a key role within this association where faster stimulus speeds were associated with a more marked decrease in coincidence anticipation performance.

Girls in detail, boys in shape: gender differences when drawing cubes in depth

The current study tested gender differences in the developmental transition from drawing cubes in two- versus three dimensions (3D), and investigated the underlying spatial abilities. Six- to nine-year-old children (N = 97) drew two occluding model cubes and solved several other spatial tasks. Girls more often unfolded the various sides of the cubes into a layout, also called diagrammatic cube drawing (object design detail). In girls, the best predictor for drawing the cubes was Mental Rotation Test (MRT) accuracy. In contrast, boys were more likely to preserve the optical appearance of the cube array. Their drawing in 3D was best predicted by MRT reaction time and the Embedded Figures Test (EFT). This confirmed boys' stronger focus on the contours of an object silhouette (object shape). It is discussed whether the two gender-specific approaches to drawing in three dimensions reflect two sides of the appearance-reality distinction in drawing, that is graphic syntax of object design features versus visual perception of projective space.

Perceiving children's behavior and reaching limits in a risk environment

The purpose of this study was to investigate the accuracy of parents' perception of children's reaching limits in a risk scenario. A sample of 68 parents of 1- to 4-year-olds were asked to make a prior estimate of their children's behavior and action limits in a task that involved retrieving a toy out of the water. The action modes used for reaching, accuracy of estimates, and error tendency were investigated. Several morphological variables, walking experience, and swimming program experience were analyzed as predictors of maximum and estimated maximum reachability. Most children sat to retrieve the toy out of the water and fell in while attempting to grasp beyond their reaching limit. Nearly 80% of the parents correctly predicted their children's behavior when the toy was unreachable. Parents were cautious in predicting their children's maximum reachability (>50% underestimates). Mothers were more accurate than fathers in estimating their children's reaching limit. The prediction of children's capabilities was based partially on body dimensions and proportions.

Sex Differences in Visual Realism in Drawings of Animate and Inanimate Objects

Sex differences in a visually realistic drawing style were examined using the model of a curvy cup as an inanimate object, and the Draw-A-Person test (DAP) as a task involving animate objects, with 7- to 12-year-old children ( N = 60; 30 boys). Accurately drawing the internal detail of the cup—indicating interest in a depth feature—was not dependent on age in boys, but only in girls, as 7-year-old boys were already engaging with this cup feature. However, the age effect of the correct omission of an occluded handle—indicating a transition from realism in terms of function (intellectual realism) to one of appearance (visual realism)—was the same for both sexes. The correct omission of the occluded handle was correlated with bilingualism and drawing the internal cup detail in girls, but with drawing the silhouette contour of the cup in boys. Because a figure's silhouette enables object identification from a distance, while perception of detail and language occurs in nearer space, it was concluded that boys and girls may differ in the way they conceptualize depth in pictorial space, rather than in visual realism as such.