Imai Daiki


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Associate Professor

Laboratory location

Sugimoto Campus

Research Areas 【 display / non-display

Environmental physiology (including physical medicine and nutritional physiology), Sports science

Association Memberships 【 display / non-display

  • Japanese Society of Physical Fitness and Sports Medicine

Current Career 【 display / non-display

  • Osaka City University   Research Center for Urban Health and Sports   Associate Professor  

  • Osaka City University   Center for Health Science Innovation   Researcher  

  • Osaka City University   Center of Education and Research for Disaster (CERD)   Researcher  

  • Osaka City University   Graduate School of Medicine   Basic Medicine Course   Lecturer  

Graduate School 【 display / non-display

  • 2007.04

    Osaka City University  Graduate School, Division of Medicine 

  • 2005.04

    Osaka University of Health and Sport Sciences  Graduate School, Division of Sports Science 

Graduating School 【 display / non-display


    Osaka University of Health and Sport Sciences   Faculty of Physical Education  


Published Papers 【 display / non-display

  • Increase in diastolic blood pressure induced by fragrance inhalation of grapefruit essential oil is positively correlated with muscle sympathetic nerve activity.

    Kawai Eriko, Takeda Ryosuke, Ota Akemi, Morita Emiko, Imai Daiki, Suzuki Yuta, Yokoyama Hisayo, Ueda Shinya, Nakahara Hidehiro, Miyamoto Tadayoshi, Okazaki Kazunobu

    JPURNAL OF PHYSIOLOGICAL SCIENSE  70 ( 1 )  2020.01  [Refereed]

  • 視覚障がい者の健康と首尾一貫感覚(SOC)の実態調査


    都市防災研究論文集  6   9 - 14 2019.11  [Refereed]

  • The effects of aging on the distribution of cerebral blood flow with postural changes and mild hyperthermia

    Ota Akemi, Takeda Ryosuke, Imai Daiki, Naghavi Nooshin, Kawai Eriko, Saho Kosuke, Morita Emiko, Suzuki Yuta, Yokoyama Hisayo, Miyagawa Toshiaki, Okazaki Kazunobu

    EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY  119 ( 5 ) 1261 - 1272 2019.05  [Refereed]

     View Summary

    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.

    DOI PubMed

  • Aerobic Exercise Training with Brisk Walking Increases Intestinal Bacteroides in Healthy Elderly Women

    Morita Emiko, Yokoyama Hisayo, Imai Daiki, Takeda Ryosuke, Ota Akemi, Kawai Eriko, Hisada Takayoshi, Emoto Masanori, Suzuki Yuta, Okazaki Kazunobu

    NUTRIENTS  11 ( 4 )  2019.04  [Refereed]

     View Summary

    This study examined the effect of an exercise intervention on the composition of the intestinal microbiota in healthy elderly women. Thirty-two sedentary women that were aged 65 years and older participated in a 12-week, non-randomized comparative trial. The subjects were allocated to two groups receiving different exercise interventions, trunk muscle training (TM), or aerobic exercise training (AE). AE included brisk walking, i.e., at an intensity of ≥ 3 metabolic equivalents (METs). The composition of the intestinal microbiota in fecal samples was determined before and after the training period. We also assessed the daily physical activity using an accelerometer, trunk muscle strength by the modified Kraus-Weber (K-W) test, and cardiorespiratory fitness by a 6-min. walk test (6MWT). K-W test scores and distance achieved during the 6MWT (6MWD) improved in both groups. The relative abundance of intestinal Bacteroides only significantly increased in the AE group, particularly in subjects showing increases in the time spent in brisk walking. Overall, the increases in intestinal Bacteroides following the exercise intervention were associated with increases in 6MWD. In conclusion, aerobic exercise training that targets an increase of the time spent in brisk walking may increase intestinal Bacteroides in association with improved cardiorespiratory fitness in healthy elderly women.

    DOI PubMed

  • Inhibitory effects of intranasal administration of insulin on fat oxidation during exercise are diminished in young overweight individuals

    Yokoyama H, Takeda R, Kawai E, Ota A, Morita E, Imai D, Suzuki Y, Morioka T, Emoto M, Inaba M, Okazaki K

    Journal of Clinical Medicine  7 ( 10 ) 308 2018.10  [Refereed]

     View Summary

    It remains unknown whether the high insulin (INS) levels in the brain affect fat oxidation during exercise. We examined the effects of the intranasal administration of INS, which increases the INS concentration in the cerebrospinal fluid when peripheral effects are lacking, on the maximum fat oxidation rate (maxFOR) and its intensity (FATmax) during exercise in 15 young normal-weight (N group) and eight young overweight (O group) individuals. On two separate days, either INS or placebo (PL) was randomly administered intranasally before a graded exercise test. Indirect calorimetry was used to assess maxFOR and FATmax during exercise. Blood INS and glucose levels did not change after INS administration. In the N group, maxFOR and FATmax were significantly smaller in the INS trial than in the PL trial. MaxFOR was significantly smaller in the O group than in the N group and was not influenced by INS administration. Exercise-induced elevation in blood epinephrine levels tended to be reduced by INS administration only in the N group. Intranasal INS administration reduces fat oxidation during exercise without any peripheral effects, possibly by suppressing sympathetic nerve activity. This inhibitory effect is diminished in overweight subjects, suggesting that cerebral insulin effects are attenuated in this population.

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Review Papers (Misc) 【 display / non-display

  • Effects of cold and mental stress on endurance exercise performance.

    Imai D, Takeda R, Kawai E, Saho K, Ota A, Morita E, Suzuki Y, Yokoyama H, Okazaki K

    The Journal of Physical Fitness and Sports Medicine  9 ( 6 ) 316 - 316 2020.11  [Refereed]  [Invited]

  • Effects of dual stress of whole body cold exposure and mental load on endurance exercise performance.

    Imai D, Takeda R, Kawai E, Saho K, Ota A, Morita E, Suzuki Y, Yokoyama H, Okazaki

    The Journal of Physical Fitness and Sports Medicine  8 ( 6 ) 338 - 338 2019.11

  • Enhanced erythropoietin release to hypoxia with an expanded plasma volume after exercise in warm environment.

    • Okazaki K, Takeda R, Imai D, Kawai E, Ota A, Saho K, Morita E, Suzuki Y, Goto K, Yokoyama H

    The Journal of Physical Fitness and Sports Medicine  7 ( 6 ) 412 2018  [Refereed]  [Invited]

Conference Activities & Talks 【 display / non-display

  • Influence of mental load with whole body cold exposure prior to exercise on endurance exercise performance

    Imai D, Takeda R, Kawai E, Saho K, Ota A, Morita E, Suzuki Y, Yokoyama H, Okazaki K

    Virtual 8th International Conference on the Physiology and Pharmacology of Temperature Regulation (vPPTR) 2020 (Vancouver)  2020.11 

  • The effects of skin temperatures on heart rate response and plasma volume expansion to exercise

    Okazaki K, Takeda R, Imai D, Kawai E, Ota A, Yokoyama H

    Virtual 8th International Conference on the Physiology and Pharmacology of Temperature Regulation (vPPTR) 2020 (Vancouver)  2020.11 

  • Mental stress do not impair aerobic exercise performance after whole body cold exposure

    Imai D, Takeda R, Kawai E, Saho K, Ota A, Morita E, Suzuki Y, Yokoyama H, Okazaki K

    The 97th Annual Meeting if the Physiological Society of Japan (Oita)  2020.03 

  • Exercise habit is associated with lower fall risks among elderly people living in urban areas.

    Yokoyama H, Watanabe H, Saito K, Shibata A, Suzuki Y, Imai D, Okazaki K, Ogita A.

    1st World Congress on Falls and Postural Stability (Kuala Lumpur)  2019.12 

  • Improved thermal comfort were associated with the attenuated heat stress during exercise wearing with a firefighting suit after heat acclimation program for firefighters.

    Okazaki K, Takeda R, Saho K, Imai D, Kawai E, Ota A, Morita E, Suzuki Y, Yokoyama H, Hayashi H, Takahashi H

    14th International Congress of Physiological Anthropology 2019 (Singapore)  2019.09 

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Other educational activity and Special note 【 display / non-display

  • Extra-Curricular Activities