2134/11373
Phil Watson
Phil
Watson
Kay Head
Kay
Head
Alain Pitiot
Alain
Pitiot
Peter Morris
Peter
Morris
Ronald J. Maughan
Ronald J.
Maughan
Effect of exercise and heat-induced hypohydration on brain volume
Loughborough University
2013
Dehydration
Hyperosmolality
Cerebrospinal fluid
MRI
Medical and Health Sciences not elsewhere classified
2013-01-09 09:43:34
Journal contribution
https://repository.lboro.ac.uk/articles/journal_contribution/Effect_of_exercise_and_heat-induced_hypohydration_on_brain_volume/9619403
Purpose: The aim of the present study was to quantify changes in brain volume
following exercise/heat-induced hypohydration in man. Methods: Eight active men
completed intermittent exercise in a warm environment, until 2.9 ± 0.1 % of body
mass was lost. Subjects remained hypohydrated for two hours following the end of
exercise. Brain volume was measured before, immediately following, and 1h and 2h
after exercise using MRI (Philips 3T Achieva). Measures of subjective feelings and
core body temperature were also monitored. Blood samples were drawn to determine
serum electrolyte concentrations and osmolality and to allow calculation of changes in
blood and plasma volumes. Results: Brain volume was not influenced by
hypohydration (0.2 ± 0.4 %; ES 0.2; P = 0.310). Reductions in ventricular (4.0 ± 1.8
%; ES 4.6; P < 0.001) and CSF (3.1 ± 1.9%; ES 3.3; P = 0.003) volumes were
observed following exercise. Compared with pre-exercise levels, serum osmolality
was elevated throughout the 2h post-exercise period (+10 ± 2 mosmol/kg; P < 0.001).
Core temperature increased from 37.1 ± 0.3oC at rest to 39.3 ± 0.5oC at the end of
exercise (P = 0.001). Conclusions: These data demonstrate that brain volume remains
unchanged in response to moderate hypohydration and the presence of serum
hyperosmolality, suggesting that mechanisms are in place to defend brain volume.