Effects of acute exercise on visual reaction time

Neural mechanisms of long-term exercise intervention on cognitive performance among short-sleep young adults: A hemodynamic study

OBJECTIVES

Short-sleep is becoming increasingly common and may negatively affect brain function including cognitive ability. Physical exercise has been proved to improve cognitive function while intensity matters. This study was conducted to examine the effects of 12-week exercise interventions on cognitive performance and prefrontal cortex activation related to task performance in short-sleep young adults.

METHODS

A total of 50 subjects (23.62 ± 5.28 years and 24 men) with regular short-sleep conditions (<7 h per night) participated in this study and were divided into three groups: control, moderate-intensity continuous training (MICT), and high-intensity interval training (HIIT) group. As task performance (congruent and incongruent Stroop) was monitored, changes in prefrontal oxygenated hemoglobin (oxyHb), an indicator of cortical activation, were measured using functional near-infrared spectroscopy (fNIRS) to explore the hemodynamics mechanism.

RESULTS

Post 12-week intervention, significant differences in reaction time for congruent [β (95%CI): -0.045 (-0.088, -0.002), p = 0.039] and incongruent Stroop tests [β (95%CI): -0.058 (-0.113, -0.003), p = 0.038] were found only in the MICT intervention group. However, HIIT did not show significant improvements in cognitive function. Left middle frontal gyrus (Frontal Mid L) and right dorsolateral superior frontal gyrus (Frontal Sup R) were both stimulated by MICT and HIIT. Moreover, left dorsolateral superior frontal gyrus (Frontal Sup L) was stimulated by MICT.

CONCLUSION

The findings indicated that 12-week MICT improved cognition by significantly increasing cortical activity across more brain regions. Thus, we suggested that maintaining moderate-intensity exercise could benefit cognitive function despite short sleep.

The brain in motion-cognitive effects of simultaneous motor activity

During the last 30 years, a large number of behavioral studies have investigated the effect of simultaneous exercise on cognitive functions. The heterogeneity of the results has been attributed to different parameters, such as intensity or modality of physical activity, and the investigated cognitive processes. More recent methodological improvements have enabled to record electroencephalography (EEG) during physical exercise. EEG studies combining cognitive tasks with exercise have described predominantly detrimental effects on cognitive processes and EEG parameters. However, differences in the underlying rationale and the design of EEG versus behavioral studies make direct comparisons between both types of studies difficult. In this narrative review of dual-task experiments we evaluated behavioral and EEG studies and discuss possible explanations for the heterogeneity of results and for the discrepancy between behavioral and EEG studies. Furthermore, we provide a proposal for future EEG studies on simultaneous motion to be a useful complement to behavioral studies. A crucial factor might be to find for each cognitive function the motor activity that matches this function in terms of attentional focus. This hypothesis should be investigated systematically in future studies.

A Review of Cognitive Changes During Acute Aerobic Exercise

A growing body of work has investigated the effects of acute, or single bouts of, aerobic exercise on cognitive function. However, review of this research has largely focused on changes following exercise, with less focus on cognitive changes during exercise. The purpose of this review is to discuss the critical characteristics of this literature to date, including: (1) what has been done, (2) what has been found, and (3) what is next. Furthermore, previous meta-analytic reviews have demonstrated there is a small positive effect on cognition when measured during exercise, with executive functions showing the largest effects. However, these reviews group executive functions together. Here we explore how inhibition, working memory and cognitive flexibility are individually impacted by factors such as exercise intensity or duration. Searches of electronic databases and reference lists from relevant studies resulted in 73 studies meeting inclusion criteria. Studies were grouped by executive and non-executive cognitive domains, intensity and duration of exercise bouts. Within the executive domain, we found that effects on working memory and cognitive flexibility remain mixed, effects on inhibition are clearer. Moderate intensity exercise improves response time, vigorous intensity impairs accuracy. Moderate to vigorous intensity improves response time across non-executive domains of attention, motor speed and information processing, with no significant effects on accuracy. Memory processes are consistently improved during exercise. Effects of exercise duration on response time and accuracy are nuanced and vary by cognitive domain. Studies typically explore durations of 45 min or less, extended exercise durations remain largely unexplored. We highlight factors to consider when assessing exercise-cognition relationships, as well as current gaps and future directions for work in this field.

Altered Spatiotemporal Gaze Dynamics During Unexpected Obstacle Negotiation in a Fatigued State

Humans use their peripheral vision during locomotion to perceive an approaching obstacle in their path, while also focusing central gaze on steps ahead of them. However, certain physiological and psychological factors may change this strategy, such as when a walker is physically fatigued. In this study, 21 healthy participants walked through a dark room while wearing eye tracking glasses before and following intense exercise. Obstacles were placed in random locations along their path and became illuminated when participants approached them. Results indicate that, when fatigued, participants had altered spatial gaze strategies, including more frequent use of central gaze to perceive obstacles and an increased gaze angular displacement. However, there were no changes in temporal gaze strategies following exercise. These findings reveal how physical fatigue alters one's visual perception of their environment during locomotion, and may partially explain why people are at greater risk of trips and falls while fatigued.

Physical Activity and Music to Counteract Mental Fatigue

Mental fatigue impairs both cognitive and physical performance. Bioactive substances (e.g., caffeine) have been used to counteract mental fatigue but could have side effects. The present study aimed to test two non-bioactive strategies to counteract mental fatigue: physical activity and listening to music. The participants first performed an arm-pointing task, then carried out a 32-min cognitively demanding task to induce mental fatigue (TLDB task), followed by another arm-pointing task at the end of the experiment. Between the end of the cognitively demanding task and the last arm-pointing task, 20 min went during which participants performed either 15 min of physical activity, of listening to music or of discussion (control). The subjective feeling of mental fatigue was assessed before each arm-pointing task and after the cognitively demanding task. For "physical activity" and "listening to music" groups, EEG was recorded at rest after each evaluation of subjective feeling of mental fatigue and during the cognitively demanding task. An increase in alpha power during the cognitively demanding task evidenced the presence of mental fatigue, without recovery during the following 20-min period. In the control condition, the arm-pointing task performance was deteriorated 20-min after the cognitively demanding task, while it remained stable after both physical activity and listening to music. Furthermore, recovery on the subjective feeling of mental fatigue was similar for both groups. The present results suggested that practicing physical activity and listening to music could be efficient strategies to counteract the negative effects of mental fatigue on motor performances.

The impact of fencing training symmetrisation on simple reaction time

Study aim: The symmetrisation of movements can be a way to develop individual coordinative skills, and to prevent the occur-rence of injuries. For this reason, in this study an attempt was made to evaluate and compare simple reaction time and movement time for épée fencers of different sports classes, and to determine the impact that three years of symmetrisation training and unilateral training have on the speed of reaction components and on dynamical asymmetry.

Material and methods: The study was conducted on 60 women épée fencers of different sports classes, and it was repeated in two groups after three years of unilateral and symmetrisation training. Simple reaction time and movement time for the dominant and the non-dominant hand were analysed using Vienna Test System.

Results: Women épée fencers of high sports class were characterised by a significantly faster reaction time than their less experienced colleagues. In tests conducted after three years of symmetrisation training, athletes from the experimental group achieved also much better results in reaction time (RT) than those from the control group training with the unilateral method.

Conclusions: Long-time unilateral training of master class women épée fencers led to dynamical asymmetry, which in the future could cause injuries and have a negative impact on the development of selected motor skills. Symmetrical training conducted in the experimental group had a positive impact on reaction time indicators as well as on movement time indicators, and it prevented the occurrence of dynamical asymmetry in the tested competitors. Thus, it can be inferred that symmetrical exercises will have a positive impact on training effectiveness and on versatility of athletes.

Slowed response to peripheral visual stimuli during strenuous exercise

Recently, we proposed that strenuous exercise impairs peripheral visual perception because visual responses to peripheral visual stimuli were slowed during strenuous exercise. However, this proposal was challenged because strenuous exercise is also likely to affect the brain network underlying motor responses. The purpose of the current study was to resolve this issue. Fourteen participants performed a visual reaction-time (RT) task at rest and while exercising at 50% (moderate) and 75% (strenuous) peak oxygen uptake. Visual stimuli were randomly presented at different distances from fixation in two task conditions: the Central condition (2° or 5° from fixation) and the Peripheral condition (30° or 50° from fixation). We defined premotor time as the time between stimulus onset and the motor response, as determined using electromyographic recordings. In the Central condition, premotor time did not change during moderate (167±19ms) and strenuous (168±24ms) exercise from that at rest (164±17ms). In the Peripheral condition, premotor time significantly increased during moderate (181±18ms, P<0.05) and strenuous exercise (189±23ms, P<0.001) from that at rest (173±17ms). These results suggest that increases in Premotor Time to the peripheral visual stimuli did not result from an impaired motor-response network, but rather from impaired peripheral visual perception. We conclude that slowed response to peripheral visual stimuli during strenuous exercise primarily results from impaired visual perception of the periphery.

The effects of a personal oxygen supplement on performance, recovery, and cognitive function during and after exhaustive exercise

The purpose of this investigation was to examine the effects of a personal oxygen supplement (OS) on performance during exhaustive exercise, respiratory responses during exhaustive exercise, and cognitive function after exhaustive exercise. The participants for this blind placebo-controlled experiment were apparently healthy college-aged adults (n = 20). First, VO2max was assessed (47.6 ± 9.8 ml O2·kg(-1)·min(-1)). Participants then ran 2 trials at 80% of VO2max speed to exhaustion and received either a placebo (compressed air) or personal OS. Psychomotor vigilance testing (PVT) was performed before and after each trial. Performance between treatments was evaluated through repeated measures analysis of variance (ANOVA) and was not found to be different (p = 0.335, ηp2 = 0.052), and order (placebo first or personal OS first) was not significant within the model (p = 0.305, ηp2 = 0.058). Mean times were 1,057.6 ± 619.8 seconds for the oxygen trials and 992.5 ± 463.1 seconds for the placebo trials. Repeated measures ANOVAs were used to assess minute ventilation (Ve, L·min(-1)) and VCO2 (L·O2·min(-1)) during exercise and recovery, mean heart rate during recovery, and PVT results. Treatment was nonsignificant (p > 0.05) nor were any interaction effects (treatment × time, p > 0.05) for any variables. The results of this study suggest that a personal OS had no effect on performance and did not affect ventilation even at the time directly surrounding the application. The results of the study also suggest that personal OS do not enhance exercise recovery or cognition during exercise recovery.

Does cerebral oxygenation affect cognitive function during exercise?

This study tested whether cerebral oxygenation affects cognitive function during exercise. We measured reaction times (RT) of 12 participants while they performed a modified version of the Eriksen flanker task, at rest and while cycling. In the exercise condition, participants performed the cognitive task at rest and while cycling at three workloads [40, 60, and 80% of peak oxygen uptake ([Formula: see text])]. In the control condition, the workload was fixed at 20 W. RT was divided into premotor and motor components based on surface electromyographic recordings. The premotor component of RT (premotor time) was used to evaluate the effects of acute exercise on cognitive function. Cerebral oxygenation was monitored during the cognitive task over the right frontal cortex using near-infrared spectroscopy. In the exercise condition, we found that premotor time significantly decreased during exercise at 60% peak [Formula: see text] relative to rest. However, this improvement was not observed during exercise at 80% peak [Formula: see text]. In the control condition, premotor time did not change during exercise. Cerebral oxygenation during exercise at 60% peak [Formula: see text] was not significantly different from that at rest, while cerebral oxygenation substantially decreased during exercise at 80% peak [Formula: see text]. The present results suggest that an improvement in cognitive function occurs during moderate exercise, independent of cerebral oxygenation.

Reaction time to peripheral visual stimuli during exercise under hypoxia

The purpose of this study was to test the hypothesis that decrease in cerebral oxygenation compromises an individual's ability to respond to peripheral visual stimuli during exercise. We measured the simple reaction time (RT) to peripheral visual stimuli at rest and during and after cycling at three different workloads [40%, 60%, and 80% peak oxygen uptake (VO2)] under either normoxia [inspired fraction of oxygen (FIO2)=0.21] or normobaric hypoxia (FIO2=0.16). Peripheral visual stimuli were presented at 10 degrees to either the right or the left of the midpoint of the eyes. Cerebral oxygenation was monitored during the RT measurement over the right frontal cortex with near-infrared spectroscopy. We used the premotor component of RT (premotor time) to assess effects of exercise on the central process. The premotor time was significantly longer during exercise at 80% peak VO2 (normoxia: 214.2+/-33.0 ms, hypoxia: 221.5+/-30.1 ms) relative to that at rest (normoxia: 201.0+/-27.2 ms, hypoxia: 202.9+/-29.7 ms) (P<0.01). Under normoxia, cerebral oxygenation gradually increased up to 60% peak VO2 and then decreased to the resting level at 80% peak VO2. Under hypoxia, cerebral oxygenation progressively decreased as exercise workload increased. We found a strong correlation between increase in premotor time and decrease in cerebral oxygenation (r2=0.89, P<0.01), suggesting that increase in premotor time during exercise is associated with decrease in cerebral oxygenation. Accordingly, exercise at high altitude may compromise visual perceptual performance.

Reaction time to peripheral visual stimuli during exercise under normoxia and hyperoxia

The purpose of this study was to test if increased oxygen availability affected simple reaction time (RT) to peripheral visual stimuli during exercise. Twelve male participants performed RT tasks at rest, during cycling with three different workloads (100, 150, and 200 W), and after exercise. We fractionated RT into Premotor time and Motor time. Under normoxia, Premotor time significantly increased during exercise at 200 W (mean +/- SD, 224.7 +/- 34.8 ms) relative to that at rest (213.3 +/- 34.1 ms) (P < 0.05). In contrast, we found no difference in Premotor time between at rest (214.0 +/- 27.0 ms) and at 200 W (213.0 +/- 21.6 ms) under hyperoxia. Furthermore, Premotor time significantly decreased at 150 W (201.3 +/- 22.4 ms) relative to that at rest under hyperoxia (P < 0.05). These results suggest that increased oxygen availability during exercise has beneficial effects on perceptual performance.