Akemi Ota1,2, Ryosuke Takeda3, Daiki Imai1,3, Nooshin Naghavi1, Eriko Kawai1, Kosuke Saho1, Emiko Morita1, Yuta Suzuki1,3, Hisayo Yokoyama1,3, Toshiaki Miyagawa1,3, Kazunobu Okazaki4,5. 1. Department of Environmental Physiology for Exercise, Osaka City University Graduate School of Medicine, 3-3-138 Sugimoto Sumiyoshi, 558-8585, Osaka, Japan. 2. Department of Health Promotion and Sports Science, Osaka Electro-Communication University, Osaka, Japan. 3. Research Center for Urban Health and Sports, Osaka City University, Osaka, Japan. 4. Department of Environmental Physiology for Exercise, Osaka City University Graduate School of Medicine, 3-3-138 Sugimoto Sumiyoshi, 558-8585, Osaka, Japan. okazaki@sports.osaka-cu.ac.jp. 5. Research Center for Urban Health and Sports, Osaka City University, Osaka, Japan. okazaki@sports.osaka-cu.ac.jp.
Abstract
PURPOSE: Cerebral blood flow (CBF) would be impaired with dual stresses of heat and orthostatic changes, even if those stresses are mild, in the elderly with declined cardio- and cerebrovascular functions with aging. To test the hypothesis, we compared the response of blood flow in the internal carotid artery (ICA) and vertebral artery (VA) to dual stresses of heat and orthostatic changes between the elderly and young individuals. METHODS: Nine elderly and eight young healthy men (71.3 ± 3.0 and 23.3 ± 3.1 years, mean ± SD, respectively) underwent measurements of blood flow in the ICA, VA and external carotid artery (ECA) via ultrasonography. The measurements were obtained in sitting and supine positions under normothermic (NT) and mildly hyperthermic (HT) conditions (ambient temperature 28 °C). Esophageal temperatures increased from NT (36.4 ± 0.2 °C, mean ± SE) to HT (37.4 ± 0.2 °C) with lower legs immersion in 42 °C water. RESULTS: With heat stress, ECA blood flow increased in both postures in both age groups (effect of heat, p < 0.001), whereas ICA blood flow remained unchanged. With postural changes from supine to sitting, ECA blood flow remained unchanged whereas ICA blood flow decreased (effect of posture, p = 0.027) by 18% in NT in the young and by 20% in HT in the elderly. VA blood flow remained unchanged under both heat stress and postural changes. CONCLUSIONS: The CBF is impaired under dual stresses of heat and orthostatic changes in healthy aged individuals, even if the levels of the stresses are mild.
PURPOSE: Cerebral blood flow (CBF) would be impaired with dual stresses of heat and orthostatic changes, even if those stresses are mild, in the elderly with declined cardio- and cerebrovascular functions with aging. To test the hypothesis, we compared the response of blood flow in the internal carotid artery (ICA) and vertebral artery (VA) to dual stresses of heat and orthostatic changes between the elderly and young individuals. METHODS: Nine elderly and eight young healthy men (71.3 ± 3.0 and 23.3 ± 3.1 years, mean ± SD, respectively) underwent measurements of blood flow in the ICA, VA and external carotid artery (ECA) via ultrasonography. The measurements were obtained in sitting and supine positions under normothermic (NT) and mildly hyperthermic (HT) conditions (ambient temperature 28 °C). Esophageal temperatures increased from NT (36.4 ± 0.2 °C, mean ± SE) to HT (37.4 ± 0.2 °C) with lower legs immersion in 42 °C water. RESULTS: With heat stress, ECA blood flow increased in both postures in both age groups (effect of heat, p < 0.001), whereas ICA blood flow remained unchanged. With postural changes from supine to sitting, ECA blood flow remained unchanged whereas ICA blood flow decreased (effect of posture, p = 0.027) by 18% in NT in the young and by 20% in HT in the elderly. VA blood flow remained unchanged under both heat stress and postural changes. CONCLUSIONS: The CBF is impaired under dual stresses of heat and orthostatic changes in healthy aged individuals, even if the levels of the stresses are mild.
Authors: R J Woodman; D A Playford; G F Watts; C Cheetham; C Reed; R R Taylor; I B Puddey; L J Beilin; V Burke; T A Mori; D Green Journal: J Appl Physiol (1985) Date: 2001-08
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