Cerebral oxygenation is reduced during hyperthermic exercise in humans
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Cerebral oxygenation is reduced during hyperthermic exercise in humans. / Rasmussen, Peter; Nybo, Lars; Volianitis, S.; Møller, K.; Secher, Niels H.; Gjedde, Albert; Rasmussen, Peter; Nybo, L; Volianitis, Stefanos; Møller, Kirsten; Secher, N H; Gjedde, Albert.
In: Acta Physiologica (Print Edition), Vol. 199, No. 1, 01.05.2010, p. 63-70.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Cerebral oxygenation is reduced during hyperthermic exercise in humans
AU - Rasmussen, Peter
AU - Nybo, Lars
AU - Volianitis, S.
AU - Møller, K.
AU - Secher, Niels H.
AU - Gjedde, Albert
AU - Rasmussen, Peter
AU - Nybo, L
AU - Volianitis, Stefanos
AU - Møller, Kirsten
AU - Secher, N H
AU - Gjedde, Albert
N1 - CURIS 2010 5200 055
PY - 2010/5/1
Y1 - 2010/5/1
N2 - Abstract Aim: Cerebral mitochondrial oxygen tension (P(mito)O(2)) is elevated during moderate exercise, while it is reduced when exercise becomes strenuous, reflecting an elevated cerebral metabolic rate for oxygen (CMRO(2)) combined with hyperventilation-induced attenuation of cerebral blood flow (CBF). Heat stress challenges exercise capacity as expressed by increased rating of perceived exertion (RPE). Methods: This study evaluated the effect of heat stress during exercise on P(mito)O(2) calculated based on a Kety-Schmidt-determined CBF and the arterial-to-jugular venous oxygen differences in eight males [27 +/- 6 years (mean +/- SD) and maximal oxygen uptake (VO(2max)) 63 +/- 6 mL kg(-1) min(-1)]. Results: The CBF, CMRO(2) and P(mito)O(2) remained stable during 1 h of moderate cycling (170 +/- 11 W, approximately 50% of VO(2max), RPE 9-12) in normothermia (core temperature of 37.8 +/- 0.4 degrees C). In contrast, when hyperthermia was provoked by dressing the subjects in watertight clothing during exercise (core temperature 39.5 +/- 0.2 degrees C), P(mito)O(2) declined by 4.8 +/- 3.8 mmHg (P < 0.05 compared to normothermia) because CMRO(2) increased by 8 +/- 7% at the same time as CBF was reduced by 15 +/- 13% (P < 0.05). During exercise with heat stress, RPE increased to 19 (19-20; P < 0.05); the RPE correlated inversely with P(mito)O(2) (r(2) = 0.42, P < 0.05). Conclusion: These data indicate that strenuous exercise in the heat lowers cerebral P(mito)O(2), and that exercise capacity in this condition may be dependent on maintained cerebral oxygenation.
AB - Abstract Aim: Cerebral mitochondrial oxygen tension (P(mito)O(2)) is elevated during moderate exercise, while it is reduced when exercise becomes strenuous, reflecting an elevated cerebral metabolic rate for oxygen (CMRO(2)) combined with hyperventilation-induced attenuation of cerebral blood flow (CBF). Heat stress challenges exercise capacity as expressed by increased rating of perceived exertion (RPE). Methods: This study evaluated the effect of heat stress during exercise on P(mito)O(2) calculated based on a Kety-Schmidt-determined CBF and the arterial-to-jugular venous oxygen differences in eight males [27 +/- 6 years (mean +/- SD) and maximal oxygen uptake (VO(2max)) 63 +/- 6 mL kg(-1) min(-1)]. Results: The CBF, CMRO(2) and P(mito)O(2) remained stable during 1 h of moderate cycling (170 +/- 11 W, approximately 50% of VO(2max), RPE 9-12) in normothermia (core temperature of 37.8 +/- 0.4 degrees C). In contrast, when hyperthermia was provoked by dressing the subjects in watertight clothing during exercise (core temperature 39.5 +/- 0.2 degrees C), P(mito)O(2) declined by 4.8 +/- 3.8 mmHg (P < 0.05 compared to normothermia) because CMRO(2) increased by 8 +/- 7% at the same time as CBF was reduced by 15 +/- 13% (P < 0.05). During exercise with heat stress, RPE increased to 19 (19-20; P < 0.05); the RPE correlated inversely with P(mito)O(2) (r(2) = 0.42, P < 0.05). Conclusion: These data indicate that strenuous exercise in the heat lowers cerebral P(mito)O(2), and that exercise capacity in this condition may be dependent on maintained cerebral oxygenation.
U2 - 10.1111/j.1748-1716.2010.02084.x
DO - 10.1111/j.1748-1716.2010.02084.x
M3 - Journal article
C2 - 20102344
VL - 199
SP - 63
EP - 70
JO - Acta Physiologica
JF - Acta Physiologica
SN - 1748-1708
IS - 1
ER -
ID: 19430762