Neurohumoral responses during prolonged exercise in humans

2003 ◽  
Vol 95 (3) ◽  
pp. 1125-1131 ◽  
Author(s):  
Lars Nybo ◽  
Bodil Nielsen ◽  
Eva Blomstrand ◽  
Kirsten Møller ◽  
Niels Secher
Keyword(s):  
Perceived Exertion ◽  
Prolonged Exercise ◽  
Strenuous Exercise ◽  
Trained Subjects ◽  
Perception Of Effort ◽  
Arteriovenous Difference ◽  
The Brain ◽  
Oxygen Difference ◽  
Net Release ◽  
Exercise In Humans

This study examined neurohumoral alterations during prolonged exercise with and without hyperthermia. The cerebral oxygen-to-carbohydrate uptake ratio (O2/CHO = arteriovenous oxygen difference divided by arteriovenous glucose difference plus one-half lactate), the cerebral balances of dopamine, and the metabolic precursor of serotonin, tryptophan, were evaluated in eight endurance-trained subjects during exercise randomized to be with or without hyperthermia. The core temperature stabilized at 37.9 ± 0.1°C (mean ± SE) in the control trial, whereas it increased to 39.7 ± 0.2°C in the hyperthermic trial, with a concomitant increase in perceived exertion ( P < 0.05). At rest, the brain had a small release of tryptophan (arteriovenous difference of -1.2 ± 0.3 μmol/l), whereas a net balance was obtained during the two exercise trials. Both the arterial and jugular venous dopamine levels became elevated during the hyperthermic trial, but the net release from the brain was unchanged. During exercise, the O2/CHO was similar across trials, but, during recovery from the hyperthermic trial, the ratio decreased to 3.8 ± 0.3 ( P < 0.05), whereas it returned to the baseline level of ∼6 within 5 min after the control trial. The lowering of O2/CHO was established by an increased arteriovenous glucose difference (1.1 ± 0.1 mmol/l during recovery from hyperthermia vs. 0.7 ± 0.1 mmol/l in control; P < 0.05). The present findings indicate that the brain has an increased need for carbohydrates during recovery from strenuous exercise, whereas enhanced perception of effort as observed during exercise with hyperthermia was not related to alterations in the cerebral balances of dopamine or tryptophan.

scholarly journals Carbohydrate Mouth Rinse Effects on Exercise Capacity in Pre- and Postprandial States

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Elie-J. M. Fares ◽  
Bengt Kayser
Keyword(s):  
Perceived Exertion ◽  
Time Trial ◽  
Cycle Ergometer ◽  
Time To Exhaustion ◽  
Endurance Capacity ◽  
Maximal Heart Rate ◽  
Trained Subjects ◽  
Mouth Rinses ◽  
Mouth Rinsing ◽  
The Brain

Background. Oropharyngeal receptors signal presence of carbohydrate to the brain. Mouth rinses with a carbohydrate solution facilitate corticomotor output and improve time-trial performance in well-trained subjects in a fasted state. We tested for this effect in nonathletic subjects in fasted and nonfasted state.Methods. 13 healthy non-athletic males performed 5 tests on a cycle ergometer. After measuring maximum power output (Wmax), the subjects cycled four times at 60% Wmax until exhaustion while rinsing their mouth every 5 minutes with either a 6.4% maltodextrin solution or water, one time after an overnight fast and another after a carbohydrate rich breakfast.Results. Mouth rinsing with maltodextrin improved time-to-exhaustion in pre- and postprandial states. This was accompanied by reductions in the average and maximal rates of perceived exertion but no change in average or maximal heart rate was observed.Conclusions. Carbohydrate mouth rinsing improves endurance capacity in both fed and fasted states in non-athletic subjects.

Cerebral blood flow and metabolism during exercise: implications for fatigue

2008 ◽  
Vol 104 (1) ◽  
pp. 306-314 ◽  
Author(s):  
Neils H. Secher ◽  
Thomas Seifert ◽  
Johannes J. Van Lieshout
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Perceived Exertion ◽  
Cerebral Oxygenation ◽  
Metabolic Response ◽  
Work Of Breathing ◽  
Whole Body ◽  
Strenuous Exercise ◽  
Glycogen Depletion ◽  
The Brain

During exercise: the Kety-Schmidt-determined cerebral blood flow (CBF) does not change because the jugular vein is collapsed in the upright position. In contrast, when CBF is evaluated by 133Xe clearance, by flow in the internal carotid artery, or by flow velocity in basal cerebral arteries, a ∼25% increase is detected with a parallel increase in metabolism. During activation, an increase in cerebral O2 supply is required because there is no capillary recruitment within the brain and increased metabolism becomes dependent on an enhanced gradient for oxygen diffusion. During maximal whole body exercise, however, cerebral oxygenation decreases because of eventual arterial desaturation and marked hyperventilation-related hypocapnia of consequence for CBF. Reduced cerebral oxygenation affects recruitment of motor units, and supplemental O2 enhances cerebral oxygenation and work capacity without effects on muscle oxygenation. Also, the work of breathing and the increasing temperature of the brain during exercise are of importance for the development of so-called central fatigue. During prolonged exercise, the perceived exertion is related to accumulation of ammonia in the brain, and data support the theory that glycogen depletion in astrocytes limits the ability of the brain to accelerate its metabolism during activation. The release of interleukin-6 from the brain when exercise is prolonged may represent a signaling pathway in matching the metabolic response of the brain. Preliminary data suggest a coupling between the circulatory and metabolic perturbations in the brain during strenuous exercise and the ability of the brain to access slow-twitch muscle fiber populations.

Relation Between Level of Prefrontal Activity and Subject's Performance

1999 ◽  
Vol 13 (2) ◽  
pp. 117-125 ◽  
Author(s):  
Laurence Casini ◽  
Françoise Macar ◽  
Marie-Hélène Giard
Keyword(s):  
Brain Activity ◽  
Sensory Information ◽  
Practice Phase ◽  
Trained Subjects ◽  
Anagram Task ◽  
Economic Information ◽  
Long Duration ◽  
Level Of Activity ◽  
The Brain ◽  
Processing Mechanism

Abstract The experiment reported here was aimed at determining whether the level of brain activity can be related to performance in trained subjects. Two tasks were compared: a temporal and a linguistic task. An array of four letters appeared on a screen. In the temporal task, subjects had to decide whether the letters remained on the screen for a short or a long duration as learned in a practice phase. In the linguistic task, they had to determine whether the four letters could form a word or not (anagram task). These tasks allowed us to compare the level of brain activity obtained in correct and incorrect responses. The current density measures recorded over prefrontal areas showed a relationship between the performance and the level of activity in the temporal task only. The level of activity obtained with correct responses was lower than that obtained with incorrect responses. This suggests that a good temporal performance could be the result of an efficacious, but economic, information-processing mechanism in the brain. In addition, the absence of this relation in the anagram task results in the question of whether this relation is specific to the processing of sensory information only.

scholarly journals Cerebral ammonia uptake and accumulation during prolonged exercise in humans

2005 ◽  
Vol 563 (1) ◽  
pp. 285-290 ◽  
Author(s):  
Lars Nybo ◽  
Mads K. Dalsgaard ◽  
Adam Steensberg ◽  
Kirsten Møller ◽  
Niels H. Secher
Keyword(s):  
Prolonged Exercise ◽  
Ammonia Uptake ◽  
Exercise In Humans

Effect of Physical Exhaustion on Cognitive Functioning

1997 ◽  
Vol 84 (1) ◽  
pp. 291-298 ◽  
Author(s):  
Y-A. Féry ◽  
A. Ferry ◽  
A. Vom Hofe ◽  
M. Rieu
Keyword(s):  
Reaction Time ◽  
Perceived Exertion ◽  
Short Term Memory ◽  
Strenuous Exercise ◽  
Decision Task ◽  
Short Term ◽  
Physical Effort ◽  
Difficult Decision ◽  
Central Processing ◽  
Processing Resources

Experiments utilizing reaction time to measure the effects of fatigue on cognition must discern sensitivity of peripheral and central processing to strenuous exercise. The additive factors method enables one to stipulate that if fatigue interacts with subjects' reaction time in a decision task, central processing is affected by fatigue. While pedaling at different intensities, 13 physically-fit men had to perform a series of short-term memory tests. The tests were executed during a constant workload session and a progressive workload session in which subjects pedaled until exhaustion. Subjects provided ratings on Borg's 1970 scale to measure the psychological effects of the physical effort such as perceived exertion. Allocation of processing resources was also measured to determine attentional constraints exerted by the dual-task situation. Analysis showed that decision reaction time was affected only during the exhausting bout of the progressive workload session and for the more difficult decision task. We discuss our results in the context of arousal and the allocation of processing resources.

Abstract 1654: Reduced Left Ventricular Diastolic Function Follows Prolonged Strenuous Exercise In Middle-aged Male Athletes

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Sarah A Ramer ◽  
Zion Sasson ◽  
Gian-Marco Busato ◽  
Joan A Persaud ◽  
Amrit A Malik ◽  
...  
Keyword(s):  
Diastolic Function ◽  
Prolonged Exercise ◽  
Left Ventricular ◽  
Strenuous Exercise ◽  
Middle Aged ◽  
Experimental Conditions ◽  
Male Athletes ◽  
Mitral Inflow ◽  
Significant Prolongation ◽  
Middle Aged Male

Introduction: A number of studies have demonstrated LV diastolic dysfunction after prolonged strenuous exercise. However, data remain conflicting in part because of uncontrolled and disparate experimental conditions. Hypothesis: We assessed the hypothesis that a decline in LV diastolic function follows prolonged exercise among middle aged male athletes. Methods: Eight middle aged recreational male athletes (ages 47–59, mean 52.4± 1.3 years) were recruited. On separate days at least one week apart, subjects performed continuous running of 150 min duration at low and high intensities (55% vs 80% VO2 max, respectively). On each day of exercise, subjects underwent echocardiographic assessments immediately before and 60 min following exercise. Diastolic function was assessed by standard pulsed wave Doppler and tissue Doppler techniques. Efforts were made to maintain hydration throughout, and hematocrit was checked with each echocardiographic assessment. Results: Sixty minutes following prolonged exercise, the mean resting heart rate was significantly elevated compared to baseline (81±5 vs 63±3 bpm, p<0.01) and a drop in systolic blood pressure was observed (115±4 vs 132±5mmHg, p=0.02). Baseline and post-exercise hematocrit were similar (43.3%±0.8 vs 43.4%±0.8). Mean (±sem) indices of diastolic function are summarized below and included a significant decline in peak mitral inflow E velocity, accompanied by an increase in mitral inflow A velocity which was significant after high intensity exercise. The decline in both the E/A and e’/a’ ratio was significant for both high and low exercise intensities. A significant prolongation in the IVRT and the mitral inflow E wave deceleration time were seen following low intensity exercise. Conclusions: In middle aged men, prolonged exercise is associated with diminished resting LV diastolic performance, detectable one hour following exercise. These changes appear to be independent of hydration state.

Abstract 2381: Aneurysmal Subarachnoid Hemorrhage: Metabolic and Blood Flow Patterns

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
parham moftakhar ◽  
Thomas C Glenn ◽  
John Boscardin ◽  
Neil A Martin
Keyword(s):  
Blood Flow ◽  
Phase Ii ◽  
Aneurysmal Subarachnoid Hemorrhage ◽  
Phase Iii ◽  
Entire Study ◽  
Cerebral Metabolic Rate ◽  
Study Population ◽  
Blood Flow Patterns ◽  
The Brain ◽  
Oxygen Difference

Objective: The purpose of this study is to classify and describe the clinically distinct metabolic and hemodynamic phases post-ASAH. Methods: 224 patients who suffered an ASAH (mean age 55±14; 74% female, 26% male) were examined. Patients underwent daily transcranial Doppler (TCD) and cerebral blood flow (CBF) studies (using 133 Xe clearance). Due to the paucity of data on post-hemorrhage day (PHD) 0, the internal carotid artery end-diastolic (ICA ED ) velocity, a surrogate for CBF, was used for the first 24 hours. The brain arteriovenous oxygen difference (AVDO 2 ) was recorded for each patient and the cerebral metabolic rate of oxygen (CMRO 2 ) was calculated. Clinical outcome was evaluated based on the Glasgow Outcome Scale (GOS) 6 months after rupture. Results: Following ASAH, 3 distinct hemodynamic phases arose for the entire study population. Phase I (hypoperfusion phase), occurs on the day of rupture (PHD 0) and is defined by a low ICA ED velocity (mean 17.8±1.1 cm/s), normal middle cerebral artery (MCA) velocity (mean V MCA 58.0±23.4 cm/s), and normal Lindegaard Ratio ([LR], mean 1.66±0.50). Phase II (relative hyperemia), (PHD 1–3), is characterized by an increasing ICA ED (mean 35.4±1.0 cm/s, p<0.0001), a relative hyperemia (mean CBF 15 40.1±1.5 ml/100g/minute, CMRO 2 1.17±0.41 ml/100g/min), a rising V MCA (mean 71.5±5.8 cm/sec, p<0.0001), and a rising but normal LR (mean 2.21±0.19, p<0.0001). During phase III (vasospasm phase, PHD 4–21), both the ICA ED and CBF decrease (mean ICA ED 19.9±0.9 cm/s, p<0.0001; mean CBF 15 36.8±0.7 ml/100g/minute, p=0.04), V MCA continues to rise (mean 107.6±2.9cm/sec, p<0.0001), and the LR is further increased (mean 3.25±0.08, p<0.0001). The CMRO 2 remains low (mean 1.17±0.40 ml/100g/min, p=1). Based on the GOS up to 90% of patients who experienced either a relative or absolute hyperemia had good outcomes. Conclusions: After an ASAH, 3 discrete metabolic and hemodynamic phases arise each with the potential for its own unique phase-specific management and therapy. Relative hyperemia, or “luxury perfusion,” during Phase II in the setting of non-elevated ICPs may provide some type of benefit for patients.

scholarly journals Carbohydrate supplementation and psychophysiological responses during moderate exercise in hypoxia

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
E. Tavares-Silva ◽  
F. F. Donatto ◽  
R. M. V. Medeiros ◽  
S. A. Santos ◽  
A. V. Caris ◽  
...  
Keyword(s):  
Perceived Exertion ◽  
Area Under The Curve ◽  
The Self ◽  
Rating Of Perceived Exertion ◽  
Physically Active ◽  
Psychophysiological Responses ◽  
Carbohydrate Supplementation ◽  
Perception Of Effort ◽  
Hypoxic Environment ◽  
Subjective Scale

Abstract Background Rating of Perceived Exertion (RPE) is a subjective scale to monitor overload and fatigue during exercise. Hypoxia may worsen the perception of fatigue, compromising the self-reported perception of effort and increasing RPE. The objective was to evaluate the effects of carbohydrate (CHO) supplementation on RPE during exercise in hypoxia simulating 4200 m. Methods Eight male physically active volunteers performed two exercises at 50% VO2peak and 1% slope: exercise in hypoxia + placebo or exercise in hypoxia + CHO (6% maltodextrin) with supplementation at 20, 40, and 60 min during exercise. Oxygen Saturation (SaO2%) was assessed at baseline and after exercise, while RPE and HR were measured each 10 min during the trial. Results SaO2% decreased after exercise in both conditions of hypoxia compared to rest. The RPE did not differ between groups. However, the RPE increased in hypoxia after 20 min of exercise in relation to 10 min. The Area Under the Curve (AUC) of RPE was lower in hypoxia + CHO compared to hypoxia. The AUC of the HR/RPE ratio in the hypoxia + CHO group was higher in relation to hypoxia. Conclusions Our results indicate that CHO supplementation does not change RPE induced by 60 min of exercise at 50% VO2peak in hypoxia equivalent to 4200 m at the different times analyzed. However, in hypoxia + CHO the (AUC)-60 min of total RPE decreased during exercise, while the heart rate/RPE ratio improved, indicating lower RPE in the hypoxic environment.

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