Single and choice reaction time during prolonged exercise in trained subjects: influence of carbohydrate availability

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.

Effects of different solutions consumed during exercise on cognitive function of male college soccer players

Background/Objectives: The present study aimed to investigate the effects of three solutions, i.e. carbohydrate-electrolyte-solution (CES), carbohydrate-electrolyte-protein-solution (CEPS), and placebo (PLA), on cognitive function of college soccer players.

Methods

Sixteen male college soccer players completed three main trials in a randomized cross-over study design. In each main trial, participants completed 90 min Loughborough Intermittent Shuttle Test (LIST) protocol and consumed one of three solutions. The cognitive function tests were performed; blood glucose and lactate concentrations, and several subjective measurements were also recorded in each trial.

Results

Compared with pre-exercise level, the accuracy of Rapid Visual Information Processing test (RVIPT) and the response time in Visual Search Test (VST, complex level) after LIST improved in CES and CEPS trials, but not in PLA trial. However, the accuracy of VST (complex level) decreased in both CES and CEPS trials, compared with PLA trial. CEPS consumption improved accuracy in VST (simple level), compared with CES consumption. Blood glucose concentrations were well maintained in CEPS trial, but not in CES and PLA trials.

Conclusion

It seems that both CES and CEPS consumption show certain benefits on some aspects of cognitive function in male college soccer players in Hong Kong. However, these effects may be specific to the cognitive domain tested.

Load Carriage and Physical Exertion Influence Cognitive Control in Military Scenarios

INTRODUCTION

Physical exertion has both beneficial and detrimental effects on cognitive performance, particularly cognitive control. Research into physical exertion under conditions of load carriage is particularly important given that military personnel and first responders must perform optimally under such combinatorial physical stressors. The present work sought to characterize cognitive control as a function of physical exertion and load carriage in a military operational scenario.

METHODS

Thirty-one active-duty soldiers underwent a 4-h operationally relevant and fatiguing scenario that included two 1-h foot marches under load carriage conditions of 8.8, 47.2, 50.7 kg on each of three separate days. During each foot march, they completed five 5-min blocks of an auditory go/no-go task of response inhibition.

RESULTS

Results showed that response inhibition declined with increasing load carriage and physical exertion, as evidenced by lower proportion of correct responses, higher proportion of false alarms, and lower response sensitivity between all three load conditions, particularly upon successive foot marches and time blocks within each foot march.

CONCLUSIONS

The results support previous laboratory-based work on load carriage and physical exertion and suggest that deteriorations in cognitive control witnessed in laboratory settings are more pronounced within realistic operational scenarios akin to those encountered by military personnel and first responders.

The Effect of Carbohydrate Mouth Rinsing on Multiple Choice Reaction Time During Amateur Boxing

PURPOSE

To examine whether the use of a carbohydrate mouth rinse (CMR) can improve multiple choice reaction time in amateur boxers during sparring.

METHODS

A total of 8 male amateur boxers (age 22 [3] y, stature 1.78 [0.07] m, mass 73.6 [14.2] kg) with at least 18 months of experience in the sport volunteered to participate in the study. All participants attended a familiarization session, followed by an experimental (CMR; 6% dextrose) and placebo trials in a randomized order. Participants undertook 3 × 2 minutes of sparring against an ability- and size-matched (stature and mass) opponent. Multiple choice reaction time and perceived exertion were measured before round 1 and then after each round. The respective mouth rinse was administered in a 25-mL solution for 10 seconds before each round. Magnitude-based inferences were used to compare the results of each round (mean difference; ±90% confidence limits).

RESULTS

The CMR was unlikely to have a beneficial effect on multiple choice reaction time compared with placebo (mean ± 90% confidence limits: 5 ± 9.5, 4 ± 3.4, -1 ± 8.5 lights for rounds 1 to 3, respectively) and had a possibly harmful effect on perceived exertion in round 1 (10 ± 20). There was an unlikely harmful effect on perceived exertion in rounds 2 (1 ± 12) and 3 (9 ± 23).

CONCLUSION

There is no evidence to support the use of CMR during sparring in amateur boxers.

Effects of carbohydrate and protein co-ingestion during short-term moderate-intensity exercise on cognitive function

BACKGROUND

This study aimed to investigate the effects of isocaloric carbohydrate-electrolyte solution (CES) and carbohydrates-electrolyte-protein solution (CEPS) consumed during moderate-intensity exercise on cognitive function.

METHODS

Twenty-three healthy participants (age: 21.7±1.5 years, Body Mass Index: 21.8±2.0 kg/m2, and peak oxygen consumption (VO2peak): 42.4±6.9 mL/kg/min) were recruited in the study. Participants completed two main experiment trials using a cross-over study design. In each trial, they completed 30 minutes of 70% VO2peak cycling, and one of two solutions (CES or CEPS) was consumed. A battery of cognitive function tests (imPACT Package) was administrated at rest and immediately post-exercise.

RESULTS

Blood glucose concentrations decreased in both trials. Heart rate and blood lactate concentrations increased in both trials. However, no significant main effects of the exercise on all cognitive function variables (verbal and visual memory, visual-motor speed, reaction time, impulse control, and cognitive efficiency index) were observed (all P>0.05). Also, there was no difference in any of the cognitive function variables between the CES and CEPS trials (all P>0.05).

CONCLUSIONS

There was no difference in the cognitive performance when CES or CES-PRO solutions was consumed during 30 minutes moderate-intensity cycling.

Evaluation of Simple Visual Reaction Time of Different Colored Light Stimuli in Visually Normal Students

PURPOSE

To evaluate the influence of colored light stimulus on simple visual reaction times.

METHODS

Simple visual reaction times of colored light stimuli were measured in 100 young Iranian females with the mean age of 23.02±3.45 years (range from 18 to 30 years) in response to the four visual stimuli (red, green, yellow and blue light) by using Speed Anticipation and Reaction Tester (SART) software.

RESULTS

The analysis of variance (ANOVA) test to compare visual reaction time showed a significant difference (P <0.001) between four colored light stimuli so that the maximum and minimum mean reaction times were obtained for blue- and red-colored light stimuli. Also, it was observed that the response latency for red color was significantly less compared to green color (P < 0.05).

CONCLUSION

The present study showed that individuals do not respond to visual stimuli with different colors at the same speed, which may be due to different factors involved in the visual reaction time.

Heat Exposure and Occupational Injuries: Review of the Literature and Implications

PURPOSE OF REVIEW

The burden of heat-related adverse occupational health effects, as well as traumatic injuries, is already substantial. Projected increases in mean temperatures and extreme events may increase the risk of adverse heat health effects and enhance disparities among exposed workers. This article reviews the emerging literature on the relationship between heat exposure and occupational traumatic injuries and discusses implications of this work.

RECENT FINDINGS

A recent meta-analysis of three case-crossover and five time series studies in industrialized settings reported an association of increasing occupational injuries with increasing heat exposure, with increased effect estimates for male gender and age less than 25 years, although heterogeneity in exposure metrics and sources of bias were demonstrated to varying degrees across studies. A subsequent case-crossover study in outdoor construction workers reported a 0.5% increase in the odds of traumatic injuries per 1 °C increase in maximum daily humidex (odds ratio 1.005 [95% CI 1.003-1.007]). While some studies have demonstrated reversed U-shaped associations between heat exposure and occupational injuries, different risk profiles have been reported in different industries and settings. Studies conducted primarily in industrialized settings suggest an increased risk of traumatic injury with increasing heat exposure, though the exact mechanisms of heat exposure's effects on traumatic injuries are still under investigation. The effectiveness of heat-related injury prevention approaches has not yet been established. To enhance the effectiveness of prevention efforts, prioritization of approaches should take into account not only the hierarchy of controls, social-ecological models, community and stakeholder participation, and tailoring of approaches to specific local work settings, but also methods that reduce local and global disparities and better address the source of heat exposure, including conservation-informed land-use planning, built environment, and prevention through design approaches. Participation of occupational health experts in transdisciplinary development and integration of these approaches is needed.

Impact of Carbohydrate Ingestion on Cognitive Flexibility and Cerebral Oxygenation during High-Intensity Intermittent Exercise: A Comparison between Maple Products and Usual Carbohydrate Solutions

BACKGROUND

The aim of this study was to compare the effects of carbohydrate (CHO) drinks (6% per volume) sweetened with maple (syrup or sap) to a commercial sports drink, glucose, and a control solution (water) on cognitive flexibility during high-intensity intermittent exercise.

METHODS

Eighty-five active men completed six 3-min bouts at 95% of their maximal aerobic power on a stationary bike, with 3 min of passive rest between efforts. Subjects were randomly allocated to an ingestion condition. Following each exercise bout, subjects ingested 166 mL of the experimental solution, drinking a total of 1 L of the same solution throughout the experimentation. Cognitive flexibility was measured using reaction time and accuracy on the Stroop task. The cognitive task was performed a total of 10 times, including 15 and 30 min post-exercise. Glycemia and cerebral oxygenation were also measured at each time point. Statistical analyses were performed using a two-way ANOVA (Condition × Time) with repeated measures.

RESULTS

The ingestion of maple products and the commercial sports drink led to a lesser increase in glycemia than glucose ingestion. CHO ingestion, when compared to water, induced a slight reduction in reaction times on the cognitive task, especially in the switching trials. CHO ingestion had no impact on cerebral oxygenation.

CONCLUSIONS

This study shows that CHO ingestion, regardless of its type, tends to improve cognitive performance throughout exercise, especially during difficult cognitive tasks.

The effects of hydration on cognitive performance during a simulated wildfire suppression shift in temperate and hot conditions

The effects on dehydration and cognitive performance from heat and/or physical activity are well established in the laboratory, although have not yet been studied for personnel working in occupations such as wildland firefighting regularly exposed to these types of conditions. This study aimed to investigate the effects of temperature and dehydration on seventy-three volunteer firefighters (35.7 ± 13.7 years, mean ± standard deviation) during a simulation of wildfire suppression under either control or hot (18-20; or 33-35 °C) temperature conditions. Results showed cognitive performance on the psychomotor vigilance task declined when participants were dehydrated in the heat and Stroop task performance was impaired when dehydrated late in the afternoon. Firefighters may be at risk of deteriorations in simple cognitive functions in the heat whilst dehydrated, although may also experience impairments in complex cognitive functions if dehydrated late in the day, irrespective of the environmental temperature.

Effects of Carbohydrate, Caffeine, and Guarana on Cognitive Performance, Perceived Exertion, and Shooting Performance in High-Level Athletes

Purpose: To investigate the effect of ingesting carbohydrate (CHO), caffeine  (CAF), and a guarana complex (GUAc) during a running exercise on cognitive performance, rating of perceived exertion (RPE), and shooting performance in high-level modern pentathlon athletes. Methods: A total of 10 athletes completed 4 counterbalanced sessions within a 2-wk period, corresponding to ingestions of CHO (30 g), GUAc (300 mg), CAF (200 mg), or placebo. The exercise involved a 40-min run on a treadmill at a steady speed, previously determined as a "somewhat hard" exercise (RPE 13). Shooting and cognitive performance (Simon task) were assessed in 3 phases: before exercise and ingestion, before exercise and after half ingestion, and after exercise and full ingestion. Drinks were consumed 40 min (250 mL) and 5 min (125 mL) prior to exercise and after 20 min of running (125 mL). RPE was assessed at 10-min intervals during exercise. Results: There was an interaction between drink and exercise on mean reaction time (P = .01, ηp2=.41 ) and a drink effect on RPE (P = .01, ηp2=.15 ). CHO, CAF, and GUAc enhanced the speed of information processing after exercise (P = .003, P = .004, and P = .04, respectively), but only CAF and GUAc decreased RPE (P = .002 and P = .02, respectively). Conclusion: The results highlight a beneficial effect of nutritional supplements on information processing and RPE. This finding is particularly interesting as decision-making processes are crucial in the performance of many sports.

Efeitos cognitivos do teste de esforço progressivo em eletricistas com equipamentos de proteção individual

Resumo Objetivo: verificar o efeito do esforço físico sobre as funções cognitivas de trabalhadores eletricistas utilizando equipamento de proteção individual (EPI). Métodos: participaram 28 eletricistas que trabalhavam na construção, manutenção e operação de redes de distribuição de energia. Todos do sexo masculino, sadios e aptos para a prática de exercícios físicos. As funções cognitivas foram representadas pelo teste de reação simples (TRS) e pelo nível de vigilância mental (NVM). O TRS e o NVM foram mensurados pré e pós-teste máximo progressivo, em esteira rolante, a 27 °C de temperatura seca e umidade relativa do ar de 64%. O teste consistiu em aumentos progressivos na velocidade e na inclinação da esteira até a fadiga, com utilização de EPI. Resultados: a média (desvio padrão) do TRS não foi significativamente diferente antes, 227,8 (35,1) ms, e após o exercício, 220,6 (24,6) ms. O NVM foi significativamente maior após o exercício em todas as situações: frequência crescente - 36,5 (5,1) Hz vs 39,5 (2,7) Hz, frequência decrescente - 36,0 (5,2) vs 39,0 (3,88) Hz, e frequência geral - 36,2 (4,9) vs 39,2 (3,1) Hz. Conclusão: o exercício progressivo máximo realizado com EPI não modificou o tempo de reação simples e aumentou o nível de vigilância mental de eletricistas.

Carbohydrates for Soccer: A Focus on Skilled Actions and Half-Time Practices

Carbohydrate consumption is synonymous with soccer performance due to the established effects on endogenous energy store preservation, and physical capacity maintenance. For performance-enhancement purposes, exogenous energy consumption (in the form of drinks, bars, gels and snacks) is recommended on match-day; specifically, before and during match-play. Akin to the demands of soccer, limited opportunities exist to consume carbohydrates outside of scheduled breaks in competition, such as at half-time. The link between cognitive function and blood glucose availability suggests that carbohydrates may influence decision-making and technical proficiency (e.g., soccer skills). However, relatively few reviews have focused on technical, as opposed to physical, performance while also addressing the practicalities associated with carbohydrate consumption when limited in-play feeding opportunities exist. Transient physiological responses associated with reductions in activity prevalent in scheduled intra-match breaks (e.g., half-time) likely have important consequences for practitioners aiming to optimize match-day performance. Accordingly, this review evaluated novel developments in soccer literature regarding (1) the ergogenic properties of carbohydrates for skill performance; and (2) novel considerations concerning exogenous energy provision during half-time. Recommendations are made to modify half-time practices in an aim to enhance subsequent performance. Viable future research opportunities exist regarding a deeper insight into carbohydrate provision on match-day.

Effect of protein and carbohydrate solutions on running performance and cognitive function in female recreational runners

This study compared the effects of a carbohydrate–electrolyte–protein solution (CEPS, 2% protein plus 4% carbohydrate), carbohydrate–electrolyte solution (CES, 6% carbohydrate), and noncaloric sweetened placebo (PLA) on both 21-km running performance and cognitive function. Eleven female recreational endurance runners performed a 21-km time-trial running on three occasions, separated by at least 28 days. In a randomized cross-over design, they ingested CEPS, CES, or PLA at a rate of 150 mL every 2.5 km with no time feedback. A cognitive function test was performed before and after the run. Participants ingested approximately 24 g/h carbohydrate plus 12 g/h protein in CEPS trial, and 36 g/h carbohydrate in CES trial during each 21-km trial. Time to complete the time-trial was slightly shorter (P < 0.05) during CES (129.6 ± 8.8 min) than PLA (134.6 ± 11.5 min), with no differences between CEPS and the other two trials. The CEPS trial showed higher composite of visual motor speed than the PLA trial (P < 0.05). In conclusion, CES feedings might improve 21-km time-trial performance in female recreational runners compared with a PLA. However, adding protein to the CES provided no additional time-trial performance benefit. CEPS feeding during prolonged exercise could benefit visual motor speed compared to PLA alone, but no differences in the performance of the other cognitive function tests were found.

Cognitive Performance Enhancement Induced by Caffeine, Carbohydrate and Guarana Mouth Rinsing during Submaximal Exercise

The aim of this study was to investigate the influence of serial mouth rinsing (MR) with nutritional supplements on cognitive performance (i.e., cognitive control and time perception) during a 40-min submaximal exercise. Twenty-four participants completed 4 counterbalanced experimental sessions, during which they performed MR with either placebo (PL), carbohydrate (CHO: 1.6 g/25 mL), guarana complex (GUAc: 0.4 g/25 mL) or caffeine (CAF: 67 mg/25 mL) before and twice during exercise. The present study provided some important new insights regarding the specific changes in cognitive performance induced by nutritional supplements. The main results were: (1) CHO, CAF and GUA MR likely led participants to improve temporal performance; (2) CAF MR likely improved cognitive control; and (3) CHO MR led to a likely decrease in subjective perception of effort at the end of the exercise compared to PL, GUA and CAF. Moreover, results have shown that performing 40-min submaximal exercise enhances information processing in terms of both speed and accuracy, improves temporal performance and does not alter cognitive control. The present study opens up new perspectives regarding the use of MR to optimize cognitive performance during physical exercise.

Effect of Intermittent Exercise on Multiple-Choice Reaction Times of Soccer Players

The influence of intermittent exercise on a choice-response time task was investigated. Two groups of 8 male soccer players ( M age = 20.9, SD = 2.0) participated. They spent 4.4 ( SD = 1.3) weekly hours on soccer training and had been playing soccer for 13 ( SD = 3.3) years. Multiple-choice reaction speed and response accuracy were measured four times. Between measurements, one group performed 8-min. blocks of intermittent exercise on a bicycle ergometer and one group rested. Analysis showed that reaction speed and response accuracy were not significantly different between the two groups. Furthermore, there were significant faster reaction times and a larger number of correct reactions through Block 2 in both the exercise and control group ( p<.05), probably a result of learning processes and familiarization with the task procedures. Further research towards the specific influence of mode of exercise, intensity, work-rest ratio and duration of intermittent exercise, and the sensitivity of reaction time tasks will be necessary to clarify the relationship between intermittent exercise and cognitive performance.

Effect of Carbohydrate Intake on Maximal Power Output and Cognitive Performances

The present study aimed to assess the beneficial effect of acute carbohydrate (7% CHO) intake on muscular and cognitive performances. Seventeen high levels athletes in explosive sports (fencing and squash) participated in a randomized, double-blind study consisting in series of 6 sprints (5s) with a passive recovery (25s) followed by 15 min submaximal cycling after either maltodextrine and fructose (CHO) or placebo (Pl) intake. Cognitive performances were assessed before and after sprint exercise using a simple reaction time (SRT) task at rest, a visual scanning task (VS) and a Go/Nogo task (GNG) during a submaximal cycling exercise. Results showed a beneficial effect of exercise on VS task on both conditions (Pl: −283 ms; CHO: −423 ms) and on SRT only during CHO condition (−26 ms). In the CHO condition, SRT was faster after exercise whereas no effect of exercise was observed in the Pl condition. According to a qualitative statistical method, a most likely and likely positive effect of CHO was respectively observed on peak power (+4%) and tiredness (−23%) when compared to Pl. Furthermore, a very likely positive effect of CHO was observed on SRT (−8%) and a likely positive effect on visual scanning (−6%) and Go/Nogo tasks (−4%) without any change in accuracy. In conclusion acute ingestion of 250 mL of CHO, 60 min and 30 min before exercise, improve peak power output, decrease muscular tiredness and speed up information processing and visual detection without changing accuracy.

The effect of exercise intensity on cognitive performance during short duration treadmill running

This study examined the effect of short duration, moderate and high-intensity exercise on a Go/NoGo task. Fifteen, habitually active (9 females and 6 males aged 28 ± 5 years) agreed to participate in the study and cognitive performance was measured in three sessions lasting 10 min each, performed at three different exercise intensities: rest, moderate and high. Results indicated significant exercise intensity main effects for reaction time (RT) (p = 0.01), the omission error rate (p = 0.027) and the decision error rate (p = 0.011), with significantly longer RTs during high intensity exercise compared to moderate intensity exercise (p = 0.039) and rest (p = 0.023). Mean ± SE of RT (ms) was 395.8 ± 9.1, 396.3 ± 9.1 and 433.5 ± 16.1 for rest, moderate and high intensity exercise, respectively. This pattern was replicated for the error rate with a significantly higher omission error and decision error rate during high intensity exercise compared to moderate intensity exercise (p = 0.003) and rest (p = 0.001). Mean ± SE of omission errors (%) was 0.88 ± 0.23, 0.8 ± 0.23 and 1.8 ± 0.46% for rest, moderate and high intensity exercise, respectively. Likewise, mean ± SE of decision errors (%) was 0.73 ± 0.24, 0.73 ± 0.21 and 1.8 ± 0.31 for rest, moderate and high intensity exercise, respectively. The present study’s results suggest that 10 min workout at high intensity impairs RT performances in habitually active adults compared to rest or moderate intensity exercise.

Cerebral Vascular Control and Metabolism in Heat Stress

This review provides an in-depth update on the impact of heat stress on cerebrovascular functioning. The regulation of cerebral temperature, blood flow, and metabolism are discussed. We further provide an overview of vascular permeability, the neurocognitive changes, and the key clinical implications and pathologies known to confound cerebral functioning during hyperthermia. A reduction in cerebral blood flow (CBF), derived primarily from a respiratory-induced alkalosis, underscores the cerebrovascular changes to hyperthermia. Arterial pressures may also become compromised because of reduced peripheral resistance secondary to skin vasodilatation. Therefore, when hyperthermia is combined with conditions that increase cardiovascular strain, for example, orthostasis or dehydration, the inability to preserve cerebral perfusion pressure further reduces CBF. A reduced cerebral perfusion pressure is in turn the primary mechanism for impaired tolerance to orthostatic challenges. Any reduction in CBF attenuates the brain's convective heat loss, while the hyperthermic-induced increase in metabolic rate increases the cerebral heat gain. This paradoxical uncoupling of CBF to metabolism increases brain temperature, and potentiates a condition whereby cerebral oxygenation may be compromised. With levels of experimentally viable passive hyperthermia (up to 39.5-40.0 °C core temperature), the associated reduction in CBF (∼ 30%) and increase in cerebral metabolic demand (∼ 10%) is likely compensated by increases in cerebral oxygen extraction. However, severe increases in whole-body and brain temperature may increase blood-brain barrier permeability, potentially leading to cerebral vasogenic edema. The cerebrovascular challenges associated with hyperthermia are of paramount importance for populations with compromised thermoregulatory control--for example, spinal cord injury, elderly, and those with preexisting cardiovascular diseases.

The effect of carbohydrate mouth rinse on a 30-minute arm cranking performance

The aim of this study was to examine the effect of carbohydrate mouth rinse on 30-min arm cranking performance. Twelve healthy, active males (age 21.6, standard deviation (SD)=3.1 years; mass 76.2, SD=12.2 kg) volunteered in a single-blind, randomised crossover design. Firstly they completed an incremental exercise test to exhaustion (VO2max test) on an arm crank (50W for 2 min, increasing by 10W every min). During visit 2 and 3 they arm cranked for maximal distance over 30 min at a resistance equivalent to 50% of their peak power, mouth rinsing for 5 s with either 25 ml of a tasteless 6.4% maltodextrin solution (CHO) or 25 ml of water (placebo) every 6 min. A letter cancellation test was performed pre and post exercise to measure cognitive function. The result showed that cognitive function was not significantly different between trials (P=0.874). There was no significant difference in distance arm cranked between trials (P=0.164) even though 9 out of 12 participants had improved performance on the CHO trial. In conclusion, further research is needed to determine the ergogenic effect of CHO mouth rinsing on upper body exercise performance.

Acute effects of dietary constituents on motor skill and cognitive performance in athletes

Performance in many sports is at least partially dependent on motor control, coordination, decision-making, and other cognitive tasks. This review summarizes available evidence about the ingestion of selected nutrients or isolated compounds (dietary constituents) and potential acute effects on motor skill and/or cognitive performance in athletes. Dietary constituents discussed include branched-chain amino acids, caffeine, carbohydrate, cocoa flavanols, Gingko biloba, ginseng, guarana, Rhodiola rosea, sage, L-theanine, theobromine, and tyrosine. Although this is not an exhaustive list, these are perhaps the most researched dietary constituents. Caffeine and carbohydrate have the greatest number of published reports supporting their ability to enhance acute motor skill and cognitive performance in athletes. At this time, there is insufficient published evidence to substantiate the use of any other dietary constituents to benefit sports-related motor skill or cognitive performance. The optimal dose and timing of caffeine and carbohydrate intake promoting enhanced motor skill and cognitive performance remain to be identified. Valid, reliable, and sensitive batteries of motor skills and cognitive tests should be developed for use in future efficacy studies.

Effects of blood flow to the prefrontal cortex on high-intensity exercise combined with high-decibel music

We studied the effects of high-intensity exercise (70-75% of VO2 max) combined with high-decibel music (100 dB) on cognitive function (measured by the Stroop test) and related blood flow changes to the prefrontal cortex (measured by Oxy-hemoglobin (Hb), Deoxy-Hb, tissue oxygen index (TOI), and normalized tissue hemoglobin index (nTHI)). The subjects of the study were 28 healthy female university students in their early 20s. Subjects were categorized into control group (CG), music group (MG), exercise group (Ex), and music and exercise group (MnEx). A crossover design was implemented so that all subjects participated in all test groups. We found no significant difference in reaction time between CG and MG for the neutral and incongruent tasks of Stroop test. However, there were significant improvements in the neutral and incongruent tasks for both the Ex (p < 0.01) and MnEx (p < 0.01) groups. Oxy-Hb measurements in the prefrontal cortex of the brain supported the Stroop test data. We found no difference between Ex and MnEx in the TOI; however, there was a significant decrease (p < 0.05) in MnEx compared to Ex. In addition, Ex resulted in a significant increase (p < 0.05) in nTHI as compared to CG. These results indicate that high decibel music could negatively affect prefrontal cortex activation of the brain during exercise.

Breakfast consumption and exercise interact to affect cognitive performance and mood later in the day. A randomized controlled trial

The current study assessed the interactive effect of breakfast and exercise on cognition and mood. Twelve active males completed four trials; no breakfast-rest, breakfast-rest, no breakfast-exercise or breakfast-exercise in a randomized, cross-over design. The trials consisted of; breakfast or fast, a 2h rest, exercise (treadmill run) or equivalent rest, a chocolate milk drink, a 90 min rest and an ad libitum lunch. Cognitive performance and mood were recorded frequently throughout each trial. Data was analysed as pre-exercise/rest, during and immediately post exercise/rest and post-drink. No effects were found prior to consumption of the drink. Post-drink, fasting before exercise increased mental fatigue compared to consuming breakfast before exercise and fasting before rest. Tension increased when breakfast was consumed at rest and when exercise was undertaken fasted compared to omitting breakfast before rest. Breakfast before rest decreased rapid visual information processing task speed and impaired Stroop performance. Breakfast omission improved Four Choice Reaction Time performance. To conclude, breakfast before exercise appeared beneficial for post-exercise mood even when a post-exercise snack was consumed. Exercise reversed post-breakfast cognitive impairment in active males.

Influence of carbohydrate supplementation on skill performance during a soccer match simulation

OBJECTIVES

This study investigated the influence of carbohydrate supplementation on skill performance throughout exercise that replicates soccer match-play.

DESIGN

Experimentation was conducted in a randomised, double-blind and cross-over study design.

METHODS

After familiarization, 15 professional academy soccer players completed a soccer match simulation incorporating passing, dribbling and shooting on two separate occasions. Participants received a 6% carbohydrate-electrolyte solution (CHO) or electrolyte solution (PL). Precision, success rate, ball speed and an overall index (speed-precision-success; SPS) were determined for all skills. Blood samples were taken at rest, immediately before exercise, every 15 min during exercise (first half: 15, 30 and 45 min; second half: 60, 75 and 90 min), and 10 min into the half time (half-time).

RESULTS

Carbohydrate supplementation influenced shooting (time×treatment interaction: p<0.05), where CHO attenuated the decline in shot speed and SPS index. Supplementation did not affect passing or dribbling. Blood glucose responses to exercise were influenced by supplementation (time×treatment interaction: p<0.05), where concentrations were higher at 45 min and during half-time in CHO compared with PL. Blood glucose concentrations reduced by 30±1% between half-time and 60 min in CHO.

CONCLUSIONS

Carbohydrate supplementation attenuated decrements in shooting performance during simulated soccer match-play; however, further research is warranted to optimise carbohydrate supplementation regimes for high-intensity intermittent sports.

The effects of carbohydrate ingestion on the badminton serve after fatiguing exercise

The badminton serve requires great skill and may be affected by fatigue. The aim of the present study was to determine whether carbohydrate ingestion affects badminton performance. Nine male badminton players (age 25 ± 7 years, mass 80.6 ± 8.0 kg) attended the laboratory on three occasions. The first visit involved an incremental exercise test to exhaustion to determine peak heart rate. Participants were given 1 L of a carbohydrate-electrolyte drink or a matched placebo during the experimental trials. The accuracy of 10 long and 10 short serves was determined before and after exercise. The fatiguing exercise was 33 min in duration (83 ± 10% and 84 ± 8% peak heart rate for the placebo and carbohydrate trial respectively). Capillary blood samples (20 μL) were taken before and after exercise for determination of blood glucose and lactate. There was deterioration in long serve accuracy with fatigue (P = 0.002), which carbohydrate ingestion had a tendency to prevent (P = 0.077). There was no effect of fatigue (P = 0.402) or carbohydrate ingestion (P = 0.109) on short serve accuracy. There was no difference in blood glucose concentration between trials (P = 0.851). Blood lactate concentration was higher during the placebo trial (P = 0.016). These results suggest that only the long serve is influenced by fatigue and carbohydrate had a tendency to prevent the deterioration in performance.

The effect of branched chain amino acids on psychomotor performance during treadmill exercise of changing intensity simulating a soccer game

The present study was designed to determine changes in the multiple-choice reaction time (MRT) during treadmill running simulating locomotor activity during a soccer game and to examine the effect of branched chain amino acids (BCAA) ingestion on psychomotor performance during the effort. Ten male soccer players were submitted to BCAA and placebo trials at 1-week intervals in a randomized order. BCAA (7 g) or placebo were given 1 h before exercise in a double blind manner. The running test consisted of two 45 min exercise bouts separated by a 15-min passive rest period and the whole test ended with 20-min active recovery. Running-walking speed changed from 0 to 6.4 m·s⁻¹ according to the time-motion analysis of soccer match. During the test, blood samples were taken for lactate, glucose, free fatty acid, and catecholamine determination. Following placebo treatment, MRT shortened from 320 ± 18 to 271 ± 11 ms (p < 0.001) during the first exercise bout then it increased during the resting break to 303 ± 138 ms (p < 0.05). During the second bout, MRT decreased to 280 ± 13 ms (p < 0.001). During active recovery, further shortening of MRT was noted. During BCAA trial, MRT was shorter than during placebo trial by ~10% (p < 0.05) before and during exercise. No significant differences were found between BCAA and placebo trials in biochemical indices. It is concluded that BCAA supplementation might be recommended in sport activities that change in intensity and require quick responses to external signals (e.g., soccer and other team games).

Interactive processes link the multiple symptoms of fatigue in sport competition

Muscle physiologists often describe fatigue simply as a decline of muscle force and infer this causes an athlete to slow down. In contrast, exercise scientists describe fatigue during sport competition more holistically as an exercise-induced impairment of performance. The aim of this review is to reconcile the different views by evaluating the many performance symptoms/measures and mechanisms of fatigue. We describe how fatigue is assessed with muscle, exercise or competition performance measures. Muscle performance (single muscle test measures) declines due to peripheral fatigue (reduced muscle cell force) and/or central fatigue (reduced motor drive from the CNS). Peak muscle force seldom falls by >30% during sport but is often exacerbated during electrical stimulation and laboratory exercise tasks. Exercise performance (whole-body exercise test measures) reveals impaired physical/technical abilities and subjective fatigue sensations. Exercise intensity is initially sustained by recruitment of new motor units and help from synergistic muscles before it declines. Technique/motor skill execution deviates as exercise proceeds to maintain outcomes before they deteriorate, e.g. reduced accuracy or velocity. The sensation of fatigue incorporates an elevated rating of perceived exertion (RPE) during submaximal tasks, due to a combination of peripheral and higher CNS inputs. Competition performance (sport symptoms) is affected more by decision-making and psychological aspects, since there are opponents and a greater importance on the result. Laboratory based decision making is generally faster or unimpaired. Motivation, self-efficacy and anxiety can change during exercise to modify RPE and, hence, alter physical performance. Symptoms of fatigue during racing, team-game or racquet sports are largely anecdotal, but sometimes assessed with time-motion analysis. Fatigue during brief all-out racing is described biomechanically as a decline of peak velocity, along with altered kinematic components. Longer sport events involve pacing strategies, central and peripheral fatigue contributions and elevated RPE. During match play, the work rate can decline late in a match (or tournament) and/or transiently after intense exercise bursts. Repeated sprint ability, agility and leg strength become slightly impaired. Technique outcomes, such as velocity and accuracy for throwing, passing, hitting and kicking, can deteriorate. Physical and subjective changes are both less severe in real rather than simulated sport activities. Little objective evidence exists to support exercise-induced mental lapses during sport. A model depicting mind-body interactions during sport competition shows that the RPE centre-motor cortex-working muscle sequence drives overall performance levels and, hence, fatigue symptoms. The sporting outputs from this sequence can be modulated by interactions with muscle afferent and circulatory feedback, psychological and decision-making inputs. Importantly, compensatory processes exist at many levels to protect against performance decrements. Small changes of putative fatigue factors can also be protective. We show that individual fatigue factors including diminished carbohydrate availability, elevated serotonin, hypoxia, acidosis, hyperkalaemia, hyperthermia, dehydration and reactive oxygen species, each contribute to several fatigue symptoms. Thus, multiple symptoms of fatigue can occur simultaneously and the underlying mechanisms overlap and interact. Based on this understanding, we reinforce the proposal that fatigue is best described globally as an exercise-induced decline of performance as this is inclusive of all viewpoints.

Carbohydrate administration and exercise performance: what are the potential mechanisms involved?

It is well established that carbohydrate (CHO) administration increases performance during prolonged exercise in humans and animals. The mechanism(s), which could mediate the improvement in exercise performance associated with CHO administration, however, remain(s) unclear. This review focuses on possible underlying mechanisms that could explain the increase in exercise performance observed with the administration of CHO during prolonged muscle contractions in humans and animals. The beneficial effect of CHO ingestion on performance during prolonged exercise could be due to several factors including (i) an attenuation in central fatigue; (ii) a better maintenance of CHO oxidation rates; (iii) muscle glycogen sparing; (iv) changes in muscle metabolite levels; (v) reduced exercise-induced strain; and (vi) a better maintenance of excitation-contraction coupling. In general, the literature indicates that CHO ingestion during exercise does not reduce the utilization of muscle glycogen. In addition, data from a meta-analysis suggest that a dose-dependent relationship was not shown between CHO ingestion during exercise and an increase in performance. This could support the idea that providing enough CHO to maintain CHO oxidation during exercise may not always be associated with an increase in performance. Emerging evidence from the literature shows that increasing neural drive and attenuating central fatigue may play an important role in increasing performance during exercise with CHO supplementation. In addition, CHO administration during exercise appears to provide protection from disrupted cell homeostasis/integrity, which could translate into better muscle function and an increase in performance. Finally, it appears that during prolonged exercise when the ability of metabolism to match energy demand is exceeded, adjustments seem to be made in the activity of the Na+/K+ pump. Therefore, muscle fatigue could be acting as a protective mechanism during prolonged contractions. This could be alleviated when CHO is administered resulting in the better maintenance of the electrical properties of the muscle fibre membrane. The mechanism(s) by which CHO administration increases performance during prolonged exercise is(are) complex, likely involving multiple factors acting at numerous cellular sites. In addition, due to the large variation in types of exercise, durations, intensities, feeding schedules and CHO types it is difficult to assess if the mechanism(s) that could explain the increase in performance with CHO administration during exercise is(are) similar in different situations. Experiments concerning the identification of potential mechanism(s) by which performance is increased with CHO administration during exercise will add to our understanding of the mechanism(s) of muscle/central fatigue. This knowledge could have significant implications for improving exercise performance.

Carbohydrate ingestion and pre-cooling improves exercise capacity following soccer-specific intermittent exercise performed in the heat

Ingestion of carbohydrate and reducing core body temperature pre-exercise, either separately or combined, may have ergogenic effects during prolonged intermittent exercise in hot conditions. The aim of this investigation was to examine the effect of carbohydrate ingestion and pre-cooling on the physiological responses to soccer-specific intermittent exercise and the impact on subsequent high-intensity exercise performance in the heat. Twelve male soccer players performed a soccer-specific intermittent protocol for 90 min in the heat (30.5°C and 42.2% r.h.) on four occasions. On two occasions, the participants underwent a pre-cooling manoeuvre. During these sessions either a carbohydrate-electrolyte solution (CHOc) or a placebo was consumed at (PLAc). During the remaining sessions either the carbohydrate-electrolyte solution (CHO) or placebo (PLA) was consumed. At 15-min intervals throughout the protocol participants performed a mental concentration test. Following the soccer-specific protocol participants performed a self-chosen pace test and a test of high-intensity exercise capacity. The period of pre-cooling significantly reduced core temperature, muscle temperature and thermal sensation (P < 0.05). Self-chosen pace was greater with CHOc (12.5 ± 0.5 km h(-1)) compared with CHO (11.3 ± 0.4 km h(-1)), PLA (11.3 ± 0.4 km h(-1)) and PLAc (11.6 ± 0.5 km h(-1)) (P < 0.05). High-intensity exercise capacity was improved with CHOc and CHO when compared with PLA (CHOc; 79.8 ± 7 s, CHO; 72.1 ± 5 s, PLAc; 70.1 ± 8 s, PLA; 57.1 ± 5 s; P < 0.05). Mental concentration during the protocol was also enhanced during CHOc compared with PLA (P < 0.05). These results suggest pre-cooling in conjunction with the ingestion of carbohydrate during exercise enhances exercise capacity and helps maintain mental performance during intermittent exercise in hot conditions.

The effect of exercise-induced arousal on cognitive task performance: a meta-regression analysis

The effects of acute exercise on cognitive performance were examined using meta-analytic techniques. The overall mean effect size was dependent on the timing of cognitive assessment. During exercise, cognitive task performance was impaired by a mean effect of -0.14. However, impairments were only observed during the first 20min of exercise. Otherwise, exercise-induced arousal enhanced performance on tasks that involved rapid decisions and automatized behaviors. Following exercise, cognitive task performance improved by a mean effect of 0.20. Arousal continued to facilitate speeded mental processes and also enhanced memory storage and retrieval. Positive effects were observed following exercise regardless of whether the study protocol was designed to measure the effects of steady-state exercise, fatiguing exercise, or the inverted-U hypothesis. Finally, cognitive performance was affected differentially by exercise mode. Cycling was associated with enhanced performance during and after exercise, whereas treadmill running led to impaired performance during exercise and a small improvement in performance following exercise. These results are indicative of the complex relation between exercise and cognition. Cognitive performance may be enhanced or impaired depending on when it is measured, the type of cognitive task selected, and the type of exercise performed.

Effects of short-term exercise and exercise training on cognitive function among patients with cardiac disease

PURPOSE

A number of studies have investigated the effect of physical activity on cognitive performance in healthy subjects although no consensus in results has been established. In patients with cardiac disease that has been associated with cognitive impairment, research regarding improvement in cognition function assumes a clinical interest. We assessed the effect of both acute exercise and aerobic training on cognitive function in patients with coronary artery disease and heart failure who participated in cardiac rehabilitation (CR).

METHODS

Twenty-four men (mean age = 51.6 +/- 6.5 years) completed 2 experimental sessions, before (S1) and after exercise training (S2). During each session, participants underwent cognitive evaluations at rest and during exercise on a cycloergometer at 30% of maximal power. Two types of evaluations were used, an exclusively cognitive test (COG, such as arithmetic test, memory test) and a tracking task (TRAC) including motor precision.

RESULTS

At S1, no significant difference appeared between rest and acute exercise for COG score (31.5 +/- 9.5 vs 32.2 +/- 10.5; ns). In contrast, acute exercise significantly improved TRAC performance (149 +/- 54 vs 140 +/- 44; P < .05). At S2, COG score improved with exercise (35.5 +/- 10.6 vs 40 +/- 10.8; P < or = .001) but TRAC score remained unchanged (138 +/- 50 vs 134 +/- 42; ns). Concerning the impact of exercise (Delta%), a significant difference was observed for COG (0.03 [-0.03 to 0.11] vs 0.14 [-0.01 to 0.24]; P < .05), before and after training, respectively, but not for TRAC.

CONCLUSIONS

Limited data are available concerning the effect of acute exercise and exercise training on cognitive function in patients with cardiac disease. This study provides evidence for the importance of CR in improving cognitive function.

The effect of a single session submaximal aerobic exercise on premotor fraction of reaction time: an electromyographic study

BACKGROUND

Numerous studies investigating the effect of exercise on reaction time have yielded contradictory results. Most of the studies use computer based methods to measure reaction time instead of electromyography, yielding total reaction time rather than premotor time. In this study, we aimed to investigate the effect of a single session aerobic exercise on premotor fraction of reaction time in sedentary healthy individuals.

METHODS

Twenty-two sedentary healthy subjects (11 subjects for the study group and 11 for the control group) enrolled in this study. Subjects in the exercise group performed a single session submaximal cycling exercise. Electromyographic reaction times were measured before and after the exercise session. In the control group, reaction time measurements were taken twice with an interval of 20 min.

FINDINGS

In the exercise group, premotor fraction of reaction time values decreased considerably (P=0.01) after the exercise session.

INTERPRETATION

A single bout of cycling exercise significantly improved premotor fraction of reaction time in healthy young sedentary subjects. Physical activity improves not only physical fitness but also cognitive functions. Electromyographic reaction time evaluations may be used in the sports medicine field where both aerobic fitness and short reaction time are indispensable demands.

Combined effects of fatigue and decision making on female lower limb landing postures: central and peripheral contributions to ACL injury risk

BACKGROUND

In spite of ongoing prevention developments, anterior cruciate ligament injury rates and the associated sex-disparity have remained, suggesting an incomplete understanding of the injury mechanism. While both fatigue and decision making are known in isolation to directly impact anterior cruciate ligament injury risk, their combined manifestations remain unknown. We thus examined the combined effects of fatigue and decision making on lower limb kinematics during sports relevant landings.

METHODS

Twenty five female National College Athletic Association athletes had initial contact and peak stance phase 3D lower limb joint kinematics quantified during anticipated and unanticipated single (left and right) leg landings, both before and during the accumulation of fatigue. Jump direction was governed by light stimuli activated prior to and during the pre-land phase of respective anticipated and unanticipated trials. To induce fatigue, subjects performed repetitive squat (n=5) and randomly ordered jump sequences, until squats were no longer possible. Subject-based measures of each dependent factor were then calculated across pre-fatigue trials, and for those denoting 100% and 50% fatigue, and submitted to a 3-way mixed design analysis of covariance to test for the main effects of fatigue time, decision and leg.

FINDINGS

Fatigue caused significant increases in initial contact hip extension and internal rotation, and in peak stance knee abduction and internal rotation and ankle supination angles. Fatigue-induced increases in initial contact hip rotations and in peak knee abduction angle were also significantly more pronounced during unanticipated compared to anticipated landings.

INTERPRETATION

The integrative effects of fatigue and decision making may represent a worst case scenario in terms of anterior cruciate ligament injury risk during dynamic single leg landings, by perpetuating substantial degradation and overload of central control mechanisms.

The interactive effect of exercise intensity and task difficulty on human cognitive processing

The interactive effect of exercise intensity and task difficulty on human cognitive processing was investigated using the P3 component of an event-related brain potential (ERP). Exercise intensity was established using Borg's rating of perceived exertion (RPE) scale, and task difficulty was manipulated using a modified flanker task comprised of incongruent and neutral trials. Twelve participants (22 to 30 y) performed the flanker task during a baseline session, and again after light (RPE: 11), moderate (RPE: 13), and hard (RPE: 15) cycling exercise. Results indicated that the P3 amplitude increases across task conditions following light and moderate cycling, but not during hard cycling, relative to baseline, suggesting that P3 amplitude may change in an inverted U fashion by as a result of acute exercise intensity. Additionally, the expected delay in P3 latency for incongruent relative to neutral trials was observed during the baseline condition. However, following acute exercise these task condition differences diminished across exercise intensities. Moreover, reaction times following all exercise conditions were shorter when compared to the baseline condition. These findings suggest that P3 latency is more sensitive to task difficulty manipulated by a flanker task than behavioral measures, and P3 latency during trials requiring greater executive control processes might be more sensitive to the effects of acute exercise than tasks requiring minimal effort.

The brain and fatigue: new opportunities for nutritional interventions?

It is clear that the cause of fatigue is complex, influenced by events occurring in both the periphery and the central nervous system. Work conducted over the last 20 years has focused on the role of brain serotonin and catecholamines in the development of fatigue, and the possibility that manipulation of neurotransmitter precursors may delay the onset of fatigue. While there is some evidence that branched-chain amino acid and tyrosine ingestion can influence perceived exertion and some measures of mental performance, the results of several apparently well-controlled laboratory studies have not demonstrated a positive effect on exercise capacity or performance under temperate conditions. As football is highly reliant upon the successful execution of motor skills and tactics, the possibility that amino acid ingestion may help to attenuate a loss in cognitive function during the later stages of a game would be desirable, even in the absence of no apparent benefit to physical performance. There are several reports of enhanced performance of high-intensity intermittent exercise with carbohydrate ingestion, but at present it is difficult to separate the peripheral effects from any potential impact on the central nervous system. The possibility that changes in central neurotransmission play a role in the aetiology of fatigue when exercise is performed in high ambient temperatures has recently been examined, although the significance of this in relation to the pattern of activity associated with football has yet to be determined.

The combined effects of hydration and exercise heat stress on choice reaction time

The purpose of this investigation was to examine the combined effects of hydration and exercise heat stress on choice reaction time. On three separate occasions eight male subjects performed cycle exercise at approximately 70% of peak power output in warm, humid conditions (31 degrees C, 63% relative humidity) for a maximum of 90 min or until exhaustion. Throughout the trials, subjects ingested either a volume of water equal to fluid loss (100-FR), a volume equivalent to approximately 50% of fluid loss (50-FR), or no fluid (0-FR). A choice reaction time task was undertaken at rest, after 20 min of cycling, 40 min of cycling and at the conclusion of exercise. Mean reaction time for 100-FR was 342.2+/-8.2 ms, 352.4+/-7.5 ms for 50-FR and 345.6+/-8.4 ms for 0-FR and were not significantly different. Choice reaction time was facilitated as the duration of exercise progressed with reaction time at 40 min and conclusion stages of exercise faster than at rest (P<0.005). Choice reaction time and accuracy were affected by the number of choices, with choice reaction time increasing linearly with the number of choices (P<0.005) and rate of incorrect responses increasing in the 4-choice task compared to the 1-choice and 2-choice task (P<0.05). The results indicate that, in up to 90 min of exercise in warm, humid conditions, choice reaction time is not compromised by different levels of hydration.

Effects of long duration exercise on cognitive function, blood glucose, and counterregulatory hormones in male cyclists

Electrocortical effects of long duration exercise on cognitive function were investigated by analyzing P300 amplitude and latency changes during a 3-h cycling exercise. P300 components were measured in 12 well-trained cyclists and blood glucose, cortisol, insulin, glycerol, and free fatty acids (FFAs) epinephrine and norepinephrine were analyzed. Results indicated that P300 components were affected by exercise with a temporary increase in amplitude between the 1st and the 2nd hour and an increase in latency after 2 h of exercise concomitant with some hormonal changes, including an increase in cortisol and epinephrine and a decrease in blood glucose. These findings suggest a combined effect of arousal and central fatigue on electrocortical indices of cognitive function during acute physical exercise.

Physiological, metabolic, and performance implications of a prolonged hill walk: influence of energy intake

We aimed to examine the effects of different energy intakes on a range of responses that are relevant to the safety of hill walkers. In a balanced design, 16 men completed a strenuous self-paced mountainous hill walk over 21 km, under either a low-energy (2.6 MJ; 616 kcal) intake (LEI) or high-energy (12.7 MJ; 3,019 kcal) intake (HEI) condition. During the hill walk, rectal temperatures were measured continuously, and blood samples for the analysis of metabolites and hormones were drawn before breakfast and immediately after the walk. Subjects also completed a battery of performance tests that included muscular strength, reaction times, flexibility, balance, and kinesthetic differentiation tests. During the LEI, mean blood glucose concentrations leveled off at the low-middle range of normoglycemia, whereas, on the HEI, they were significantly elevated compared with the LEI. The maintained blood glucose concentrations, during the LEI, were probably mediated via the marked fat mobilization, reflected by a two- to fivefold increase in nonesterified fatty acids, 3-hydroxybutyrate, and glycerol concentrations. The LEI group showed significantly slower one- and two-finger reaction time, had an impaired ability to balance, and were compromised in their ability to maintain body temperature, when compared with the HEI group. The modestly impaired performance (particularly with respect to balance) and thermoregulation during the LEI condition may increase susceptibility to both fatigue and injury during the pursuit of recreational activity outdoors.

Effects of acute physical exercise characteristics on cognitive performance

The effect of physical exercise on mental function has been widely studied from the beginning of the 20th century. However, the contradictory findings of experimental research have led authors to identify several methodological factors to control in such studies including: (i) the nature of the psychological task; and (ii) the intensity and duration of physical exercise. The purpose of this article is to provide information, from the perspective of performance optimisation, on the main effects of physical task characteristics on cognitive performance. Within this framework, some consistent results have been observed during the last decade. Recent studies, using mainly complex decisional tasks, have provided the research community with clear support for an improvement of cognitive performance during exercise. Diverse contributing factors have been suggested to enhance cognitive efficacy. First, an increase in arousal level related to physical exertion has been hypothesised. Improvement in decisional performance has been observed immediately after the adrenaline threshold during incremental exercise. Such positive effects could be enhanced by nutritional factors, such as carbohydrate or fluid ingestion, but did not seem to be influenced by the level of fitness. Second, the mediating role of resource allocation has been suggested to explain improvement in cognitive performance during exercise. This effect highlights the importance of motivational factors in such tasks. Finally, when the cognitive performance was performed during exercise, consistent results have indicated that the dual task effect was strongly related to energetic constraints of the task. The greater the energy demand, the more attention is used to control movements.