Editing Exercise physiology (section)

== Brain ==
{{main|Neurobiological effects of physical exercise}}
At rest, the [[human brain]] receives 15% of total cardiac output, and uses 20% of the body's energy consumption.<ref>{{Cite journal |last=Lassen |first=NA |year=1959 |title=Cerebral blood flow and oxygen consumption in man |journal=Physiological Reviews |volume=39 |issue=2 |pages=183–238 |doi=10.1152/physrev.1959.39.2.183 |pmid=13645234 |s2cid=29275804}}</ref> The brain is normally dependent for its high energy expenditure upon [[aerobic metabolism]]. The brain as a result is highly sensitive to failure of its oxygen supply with loss of consciousness occurring within six to seven seconds,<ref>{{Cite journal |vauthors=Rossen R, Kabat H, Anderson JP |year=1943 |title=Acute arrest of cerebral circulation in man |journal=Archives of Neurology & Psychiatry |volume=50 |issue=5 |pages=510–28 |doi=10.1001/archneurpsyc.1943.02290230022002}}</ref> with its [[EEG]] going flat in 23 seconds.<ref>{{Cite journal |last=Todd |first=MM |last2=Dunlop |first2=BJ |last3=Shapiro |first3=HM |last4=Chadwick |first4=HC |last5=Powell |first5=HC |year=1981 |title=Ventricular fibrillation in the cat: A model for global cerebral ischemia |journal=Stroke: A Journal of Cerebral Circulation |volume=12 |issue=6 |pages=808–15 |doi=10.1161/01.STR.12.6.808 |pmid=7303071 |doi-access=free}}</ref> Therefore, the brain's function would be disrupted if exercise affected its supply of oxygen and glucose.

Protecting the brain from even minor disruption is important since exercise depends upon [[motor skill|motor control]]. Because humans are bipeds, motor control is needed for keeping balance. For this reason, brain energy consumption is increased during intense physical exercise due to the demands in the motor cognition needed to control the body.<ref name="Secher, N. H. 2008">{{Cite journal |last=Secher |first=NH |last2=Seifert |first2=T |last3=Van Lieshout |first3=JJ |year=2008 |title=Cerebral blood flow and metabolism during exercise: Implications for fatigue |journal=Journal of Applied Physiology |volume=104 |issue=1 |pages=306–14 |doi=10.1152/japplphysiol.00853.2007 |pmid=17962575}}</ref>

Exercise Physiologists treat a range of neurological conditions including (but not limited to): Parkinson's, Alzheimer's, Traumatic Brain Injury, Spinal Cord Injury, Cerebral Palsy and mental health conditions.{{cn|date=April 2025}}

=== Cerebral oxygen ===
[[Autoregulation#Cerebral autoregulation|Cerebral autoregulation]] usually ensures the brain has priority to cardiac output, though this is impaired slightly by exhaustive exercise.<ref>{{Cite journal |last=Ogoh |first=S |last2=Dalsgaard |first2=MK |last3=Yoshiga |first3=CC |last4=Dawson |first4=EA |last5=Keller |first5=DM |last6=Raven |first6=PB |last7=Secher |first7=NH |year=2005 |title=Dynamic cerebral autoregulation during exhaustive exercise in humans |journal=American Journal of Physiology. Heart and Circulatory Physiology |volume=288 |issue=3 |pages=H1461–7 |doi=10.1152/ajpheart.00948.2004 |pmid=15498819}}</ref> During submaximal exercise, cardiac output increases and cerebral blood flow increases beyond the brain's oxygen needs.<ref>{{Cite journal |last=Ide |first=K |last2=Horn |first2=A |last3=Secher |first3=NH |year=1999 |title=Cerebral metabolic response to submaximal exercise |journal=Journal of Applied Physiology |volume=87 |issue=5 |pages=1604–8 |citeseerx=10.1.1.327.7515 |doi=10.1152/jappl.1999.87.5.1604 |pmid=10562597}}</ref>  However, this is not the case for continuous maximal exertion: "Maximal exercise is, despite the increase in capillary oxygenation [in the brain], associated with a reduced mitochondrial O<sub>2</sub> content during whole body exercise"<ref>{{Cite journal |last=Secher |first=NH |last2=Seifert |first2=T |last3=Van Lieshout |first3=JJ |year=2008 |title=Cerebral blood flow and metabolism during exercise: Implications for fatigue |journal=Journal of Applied Physiology |volume=104 |issue=1 |pages=306–14 |doi=10.1152/japplphysiol.00853.2007 |pmid=17962575}} page 309</ref>  The autoregulation of the brain's blood supply is impaired particularly in warm environments<ref>{{Cite journal |last=Watson |first=P |last2=Shirreffs |first2=SM |last3=Maughan |first3=RJ |year=2005 |title=Blood-brain barrier integrity may be threatened by exercise in a warm environment |journal=American Journal of Physiology. Regulatory, Integrative and Comparative Physiology |volume=288 |issue=6 |pages=R1689–94 |doi=10.1152/ajpregu.00676.2004 |pmid=15650123}}</ref>

=== Glucose ===
In adults, exercise depletes the plasma glucose available to the brain: short intense exercise (35 min ergometer cycling) can reduce brain glucose uptake by 32%.<ref name="Pmid">{{Cite journal |last=Kemppainen |first=J |last2=Aalto |first2=S |last3=Fujimoto |first3=T |last4=Kalliokoski |first4=KK |last5=Långsjö |first5=J |last6=Oikonen |first6=V |last7=Rinne |first7=J |last8=Nuutila |first8=P |last9=Knuuti |first9=J |year=2005 |title=High intensity exercise decreases global brain glucose uptake in humans |journal=The Journal of Physiology |volume=568 |issue=Pt 1 |pages=323–32 |doi=10.1113/jphysiol.2005.091355 |pmc=1474763 |pmid=16037089}}</ref>

At rest, energy for the adult brain is normally provided by glucose but the brain has a compensatory capacity to replace some of this with [[lactic acid|lactate]]. Research suggests that this can be raised, when a person rests in a [[Positron emission tomography|brain scanner]], to about 17%,<ref>{{Cite journal |last=Smith |first=D |last2=Pernet |first2=A |last3=Hallett |first3=WA |last4=Bingham |first4=E |last5=Marsden |first5=PK |last6=Amiel |first6=SA |year=2003 |title=Lactate: A preferred fuel for human brain metabolism in vivo |journal=Journal of Cerebral Blood Flow and Metabolism |volume=23 |issue=6 |pages=658–64 |doi=10.1097/01.WCB.0000063991.19746.11 |pmid=12796713 |doi-access=free}}</ref> with a higher percentage of 25% occurring during [[hypoglycemia]].<ref>{{Cite journal |last=Lubow |first=JM |last2=Piñón |first2=IG |last3=Avogaro |first3=A |last4=Cobelli |first4=C |last5=Treeson |first5=DM |last6=Mandeville |first6=KA |last7=Toffolo |first7=G |last8=Boyle |first8=PJ |year=2006 |title=Brain oxygen utilization is unchanged by hypoglycemia in normal humans: Lactate, alanine, and leucine uptake are not sufficient to offset energy deficit |journal=American Journal of Physiology. Endocrinology and Metabolism |volume=290 |issue=1 |pages=E149–E153 |doi=10.1152/ajpendo.00049.2005 |pmid=16144821 |s2cid=8297686}}</ref> During intense exercise, lactate has been estimated to provide a third of the brain's energy needs.<ref name="Pmid" /><ref name="Dalsgaard, M. K. 2006">{{Cite journal |last=Dalsgaard |first=MK |year=2006 |title=Fuelling cerebral activity in exercising man |journal=Journal of Cerebral Blood Flow and Metabolism |volume=26 |issue=6 |pages=731–50 |doi=10.1038/sj.jcbfm.9600256 |pmid=16395281 |s2cid=24976326}}</ref>  There is evidence that the brain might, however, in spite of these alternative sources of energy, still suffer an energy crisis since IL-6 (a sign of metabolic stress) is released during exercise from the brain.<ref name="Nybo, L. 2005" /><ref name="Secher, N. H. 2008" />

=== Hyperthermia ===
Humans use sweat thermoregulation for body heat removal, particularly to remove the heat produced during exercise. Moderate dehydration as a consequence of exercise and heat is reported to impair cognition.<ref>{{Cite journal |last=Baker |first=LB |last2=Conroy |first2=DE |last3=Kenney |first3=WL |year=2007 |title=Dehydration impairs vigilance-related attention in male basketball players |journal=Medicine & Science in Sports & Exercise |volume=39 |issue=6 |pages=976–83 |doi=10.1097/mss.0b013e3180471ff2 |pmid=17545888 |s2cid=25267863 |doi-access=free}}</ref><ref>{{Cite journal |last=Cian |first=C |last2=Barraud |first2=PA |last3=Melin |first3=B |last4=Raphel |first4=C |year=2001 |title=Effects of fluid ingestion on cognitive function after heat stress or exercise-induced dehydration |journal=International Journal of Psychophysiology |volume=42 |issue=3 |pages=243–51 |doi=10.1016/S0167-8760(01)00142-8 |pmid=11812391}}</ref> These impairments can start after body mass lost that is greater than 1%.<ref>{{Cite journal |last=Sharma |first=VM |last2=Sridharan |first2=K |last3=Pichan |first3=G |last4=Panwar |first4=MR |year=1986 |title=Influence of heat-stress induced dehydration on mental functions |journal=Ergonomics |volume=29 |issue=6 |pages=791–9 |doi=10.1080/00140138608968315 |pmid=3743537}}</ref> Cognitive impairment, particularly due to heat and exercise is likely to be due to loss of integrity to the blood brain barrier.<ref name="Maughan, R. J. 2007">{{Cite journal |last=Maughan |first=RJ |last2=Shirreffs |first2=SM |last3=Watson |first3=P |year=2007 |title=Exercise, heat, hydration and the brain |journal=Journal of the American College of Nutrition |volume=26 |issue=5 Suppl |pages=604S–612S |doi=10.1080/07315724.2007.10719666 |pmid=17921473 |s2cid=27256788}}</ref> Hyperthermia can also lower cerebral blood flow,<ref>{{Cite journal |last=Nybo |first=L |last2=Møller |first2=K |last3=Volianitis |first3=S |last4=Nielsen |first4=B |last5=Secher |first5=NH |year=2002 |title=Effects of hyperthermia on cerebral blood flow and metabolism during prolonged exercise in humans |journal=Journal of Applied Physiology |volume=93 |issue=1 |pages=58–64 |doi=10.1152/japplphysiol.00049.2002 |pmid=12070186}}</ref><ref>{{Cite journal |last=Nybo |first=L |last2=Nielsen |first2=B |year=2001 |title=Middle cerebral artery blood velocity is reduced with hyperthermia during prolonged exercise in humans |journal=The Journal of Physiology |volume=534 |issue=Pt 1 |pages=279–86 |doi=10.1111/j.1469-7793.2001.t01-1-00279.x |pmc=2278686 |pmid=11433008}}</ref> and raise brain temperature.<ref name="Secher, N. H. 2008" />