Effect of Exercise and Heat-Induced Hypohydration on Brain Volume

Watson, Phillip; Head, Kevin; Pitiot, Alain; Morris, Peter S.; Maughan, Ronald J.

doi:10.1249/mss.0b013e3181e39788

Cited by 30 publications

(29 citation statements)

References 26 publications

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“…There is some limited evidence that dehydration results in a change in brain volume [43], but this response has not been demonstrated in all studies [44]. Dehydration [45] and hyperthermia [46] also appear to result in transient opening of the blood–brain barrier, and this may have implications for the stability of the cerebral environment during exercise.…”

Section: Use Of Nutrition To Influence Central Fatiguementioning

confidence: 99%

Exercise, Nutrition and the Brain

2014

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Accumulating evidence suggests that diet and lifestyle can play an important role in delaying the onset or halting the progression of age-related health disorders and can improve cognitive function. Exercise has been promoted as a possible prevention for neurodegenerative diseases. Exercise will have a positive influence on cognition and it increases the brain-derived neurotrophic factor, an essential neurotrophin. Several dietary components have been identified as having effects on cognitive abilities. In particular, polyphenols have been reported to exert their neuroprotective actions through the potential to protect neurons against injury induced by neurotoxins, an ability to suppress neuroinflammation, and the potential to promote memory, learning, and cognitive function. Dietary factors can affect multiple brain processes by regulating neurotransmitter pathways, synaptic transmission, membrane fluidity, and signal-transduction pathways. Flavonols are part of the flavonoid family that is found in various fruits, cocoa, wine, tea and beans. Although the antioxidant effects of flavonols are well established in vitro, there is general agreement that flavonols have more complex actions in vivo. Several cross-sectional and longitudinal studies have shown that a higher intake of flavonoids from food may be associated with a better cognitive evolution. Whether this reflects a causal association remains to be elucidated. Several studies have tried to ‘manipulate’ the brain in order to postpone central fatigue. Most studies have clearly shown that in normal environmental circumstances these interventions are not easy to perform. There is accumulating evidence that rinsing the mouth with a carbohydrate solution will improve endurance performance. There is a need for additional well controlled studies to explore the possible impact of diet and nutrition on brain functioning.

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Section: Use Of Nutrition To Influence Central Fatiguementioning

confidence: 99%

Exercise, Nutrition and the Brain

2014

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“…It is well documented that even moderate levels of dehydration increase physiological strain, most likely via disproportionately elevation in heart rate and a concomitant reduction in cardiac output, resulting in body’s inability to dissipate heat (12, 13). Furthermore, water losses ≥ 2% of total body weight impair significantly exercise and skill performance (1, 5) both in laboratories and field studies as well as mental performance in hot environments (7, 27, 28). Moreover, recent studies indicated that even lower levels of dehydration (~ −1%) provoke unfavorable changes in the athletic performance (6, 18).…”

Section: Introductionmentioning

confidence: 99%

Fluid Balance During Training in Elite Young Athletes of Different Sports

Arnaoutis

Kavouras

Angelopoulou

et al. 2015

Journal of Strength and Conditioning Research

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Although there are many studies demonstrating a high percentage of adult athletes which start exercise in sub-optimal hydration state, limited data concerning hydration levels in athletic youth exists. The purpose of this study was to identify the hydration status of elite young athletes of different sports, during a typical day of training. Fifty-nine young elite men athletes from different sports (basketball, gymnastics, swimming, running, canoeing) participated in the study (age: 15.2±1.3 y, years of training: 7.7±2.0). Hydration status was assessed in the morning, before and immediately after practice. Data collection took place at the same time of the day, with mean environmental temperature and humidity at the time of the measurements at 27.6±0.9 °C and 58±8%, respectively. All athletes trained for approximately 90 min and they were consuming fluids ad libitum throughout their practice. Over 89% of the athletes were hypohydrated (USG≥1.020 mg/dl) based on their first morning urine sample. Pre-training urine samples revealed that 76.3% of the athletes were hypohydrated, while a significant high percent remained hypohydrated even after training according to USG values ≥ 1.020 mg/dl (74.5%) and urine color scale: 5-6 (76.3%). Mean body weight loss during training was −1.1±0.07%. We concluded that the prevalence of hypohydration among elite young athletes is very high, as indicated by the USG and urine color values. The majority of the athletes was hypohydrated throughout the day and dehydrated even more during practice despite fluid availability.

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“…They reported no significant effect of dehydration on brain volume. Results on ventricular volume ranged from decrease 12 to increase, 7,10 and Dickson et al found no changes. 11 Duning et al 13 showed a 0.55% brain volume reduction after 16 hours of thirsting and a 0.72% increase after subsequent rehydration.…”

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confidence: 96%

“…Previous brain morphometry findings in healthy subjects undergoing de- and rehydration have remained somewhat inconclusive and inconsistent in terms of the distribution of the changes and the structures affected. Kempton et al, 7,10 Dickson et al, 11 and Watson et al 12 induced dehydration by thermal exercises. They reported no significant effect of dehydration on brain volume.…”

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confidence: 99%

Responses of the Human Brain to Mild Dehydration and Rehydration Explored In Vivo by¹H-MR Imaging and Spectroscopy

Biller

Reuter

Patenaude

et al. 2015

AJNR Am J Neuroradiol

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BACKGROUND AND PURPOSE As yet, there are no in vivo data on tissue water changes and associated morphometric changes involved in the osmo-adaptation of normal brains. Our aim was to evaluate osmoadaptive responses of the healthy human brain to osmotic challenges of de- and rehydration by serial measurements of brain volume, tissue fluid, and metabolites. MATERIALS AND METHODS Serial T1-weighted and 1H-MR spectroscopy data were acquired in 15 healthy individuals at normohydration, on 12 hours of dehydration, and during 1 hour of oral rehydration. Osmotic challenges were monitored by serum measures, including osmolality and hematocrit. MR imaging data were analyzed by using FreeSurfer and LCModel. RESULTS On dehydration, serum osmolality increased by 0.67% and brain tissue fluid decreased by 1.63%, on average. MR imaging morphometry demonstrated corresponding decreases of cortical thickness and volumes of the whole brain, cortex, white matter, and hypothalamus/thalamus. These changes reversed during rehydration. Continuous fluid ingestion of 1 L of water for 1 hour within the scanner lowered serum osmolality by 0.96% and increased brain tissue fluid by 0.43%, on average. Concomitantly, cortical thickness and volumes of the whole brain, cortex, white matter, and hypothalamus/thalamus increased. Changes in brain tissue fluid were related to volume changes of the whole brain, the white matter, and hypothalamus/thalamus. Only volume changes of the hypothalamus/thalamus significantly correlated with serum osmolality. CONCLUSIONS This is the first study simultaneously evaluating changes in brain tissue fluid, metabolites, volume, and cortical thickness. Our results reflect cellular volume regulatory mechanisms at a macroscopic level and emphasize that it is essential to control for hydration levels in studies on brain morphometry and metabolism in order to avoid confounding the findings.

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Effect of Exercise and Heat-Induced Hypohydration on Brain Volume

Cited by 30 publications

References 26 publications

Exercise, Nutrition and the Brain

Exercise, Nutrition and the Brain

Fluid Balance During Training in Elite Young Athletes of Different Sports

Responses of the Human Brain to Mild Dehydration and Rehydration Explored In Vivo by¹H-MR Imaging and Spectroscopy

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Effect of Exercise and Heat-Induced Hypohydration on Brain Volume

Cited by 30 publications

References 26 publications

Exercise, Nutrition and the Brain

Exercise, Nutrition and the Brain

Fluid Balance During Training in Elite Young Athletes of Different Sports

Responses of the Human Brain to Mild Dehydration and Rehydration Explored In Vivo by1H-MR Imaging and Spectroscopy

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Product

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About

Responses of the Human Brain to Mild Dehydration and Rehydration Explored In Vivo by¹H-MR Imaging and Spectroscopy