TY - JOUR

T1 - Cerebral water and ion balance remains stable when humans are exposed to acute hypoxic exercise

AU - Avnstorp, Magnus B

AU - Rasmussen, Peter

AU - Brassard, Patrice

AU - Seifert, Thomas

AU - Overgaard, Morten

AU - Krustrup, Peter

AU - Secher, Niels H.

AU - Nordsborg, Nikolai Baastrup

N1 - CURIS 2015 NEXS 097

PY - 2015

Y1 - 2015

N2 - Avnstorp, Magnus B., Peter Rasmussen, Patrice Brassard, Thomas Seifert, Morten Overgaard, Peter Krustrup, Niels H. Secher, and Nikolai B. Nordsborg. Cerebral water and ion balance remains stable when humans are exposed to acute hypoxic exercise. High Alt Med Biol 16:000-000, 2015.-Background: Intense physical activity increases the prevalence of acute mountain sickness (AMS) that can occur within 10 h after ascent to altitudes above 1500 m and is likely related to development of cerebral edema. This study evaluated whether disturbed cerebral water and ion homeostasis can be detected when intense exercise is carried out in hypoxia and monitored the influence of muscle metabolism for changes in arterial variables.METHODS: On two separate days, in random order, 30 min cycling exercise was performed in either hypoxia (10% O2) or normoxia at an intensity that was exhaustive in the hypoxic trial (∼120 W; n=9).RESULTS: Exercise in hypoxia affected muscle metabolism, as evidenced by higher (p<0.05) leg lactate release at 7.5 min and a continuous decline in arterial pH (p<0.001) that was not observed in normoxia. Middle cerebral artery flow velocity increased (p<0.01) with exercise under both circumstances. No cerebral net exchange of Na(+) or K(+) was evident. Likewise, no significant net-exchange of water over the brain was demonstrated and the arterial and jugular venous hemoglobin concentrations were similar.CONCLUSION: Challenging exercise in hypoxia for 30 min affected muscle metabolism and increased an index of cerebral blood flow, but cerebral net water and ion homeostasis remained stable. Thus, although AMS develops within hours and may be related to exercise-induced disturbance of cerebral ion and water balance, such changes are not detectable when subjects are exposed to acute 30 min maximal exercise in hypoxia.

AB - Avnstorp, Magnus B., Peter Rasmussen, Patrice Brassard, Thomas Seifert, Morten Overgaard, Peter Krustrup, Niels H. Secher, and Nikolai B. Nordsborg. Cerebral water and ion balance remains stable when humans are exposed to acute hypoxic exercise. High Alt Med Biol 16:000-000, 2015.-Background: Intense physical activity increases the prevalence of acute mountain sickness (AMS) that can occur within 10 h after ascent to altitudes above 1500 m and is likely related to development of cerebral edema. This study evaluated whether disturbed cerebral water and ion homeostasis can be detected when intense exercise is carried out in hypoxia and monitored the influence of muscle metabolism for changes in arterial variables.METHODS: On two separate days, in random order, 30 min cycling exercise was performed in either hypoxia (10% O2) or normoxia at an intensity that was exhaustive in the hypoxic trial (∼120 W; n=9).RESULTS: Exercise in hypoxia affected muscle metabolism, as evidenced by higher (p<0.05) leg lactate release at 7.5 min and a continuous decline in arterial pH (p<0.001) that was not observed in normoxia. Middle cerebral artery flow velocity increased (p<0.01) with exercise under both circumstances. No cerebral net exchange of Na(+) or K(+) was evident. Likewise, no significant net-exchange of water over the brain was demonstrated and the arterial and jugular venous hemoglobin concentrations were similar.CONCLUSION: Challenging exercise in hypoxia for 30 min affected muscle metabolism and increased an index of cerebral blood flow, but cerebral net water and ion homeostasis remained stable. Thus, although AMS develops within hours and may be related to exercise-induced disturbance of cerebral ion and water balance, such changes are not detectable when subjects are exposed to acute 30 min maximal exercise in hypoxia.

U2 - 10.1089/ham.2014.1075

DO - 10.1089/ham.2014.1075

M3 - Journal article

C2 - 25761236

VL - 16

SP - 18

EP - 25

JO - High Altitude Medicine and Biology

JF - High Altitude Medicine and Biology

SN - 1527-0297

IS - 1

ER -