Details of the Researcher

PHOTO

Yujiro Asano
Section
Graduate School of Biomedical Engineering
Job title
Degree

  • Doctor of Philosophy in Health and Sport Sciences (University of Tsukuba)

e-Rad No.
61049011
Profile

高齢者が自立した生活を維持できる期間の延伸を目指し、身体機能・認知機能の低下を規定する要因を疫学・生理学の両面から研究しています。

特に、筋量だけでは捉えられない骨格筋の質・筋組成に着目し、生体電気インピーダンス、CT、MRI、超音波などを用いて、収縮に貢献する筋組織である筋細胞・筋線維の萎縮や、収縮に貢献しない筋組織である体水分分布・脂肪浸潤・細胞外マトリクス・結合組織に着目して、筋組成と筋力・身体機能、生活機能、要介護、死亡との関連を検討しています。

また、筋質研究を基盤に、脳構造・脳波、末梢神経、手指巧緻性、身体活動を統合し、筋量から筋力・パワー、身体機能、ADLへ至る機能低下の個人差を、解明する研究を進めています。

 

Research History 6

  • 2026/04 - Present
    National Center for Geriatrics and Gerontrogy　Visiting Research Fellow

  • 2026/04 - Present
    日本学術振興会　特別研究員（PD）（東北大学）

  • 2026/04 - Present
    Tohoku University

  • 2024/10 - 2026/03
    National Center for Geriatrics and Gerontrogy

  • 2023/04 - 2026/03
    日本学術振興会 特別研究員 (DC1)（筑波大学）

  • 2024/04 - 2025/03
    National Institutes of Biomedical Innovation, Health and Nutrition

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Education 3

  • University of Tsukuba　Degree Programs in Comprehensive Human Sciences, Graduate School of Comprehensive Human Sciences　Doctoral Program in Physical Education, Health and Sport Science

    2023/04 - 2026/03

  • University of Tsukuba　Health and Sport Sciences, Degree Programs in Comprehensive Human Sciences, Graduate School of Comprehensive Human Sciences　Master's Program in Physical Education

    2021/04 - 2023/04

  • University of Tsukuba　School of Health and Physical Education

    2017/04 - 2021/03

Research Interests 9

  • exercise epidemiology, geriatric gerontology

  • bioelectrical impedance analysis

  • muscle quality, muscle composition

  • cognitive function

  • physical function

  • 健康

  • health expectancy

  • Body composition

  • Older Adults

Awards 4

  1. 3rd Prize in the Presentation Competition

    2026/07　Powerpenia Conference 2026　Vertical-jump-defined powerpenia in community-dwelling older adults: a multi-indicator comparison of age-related decline and prediction of incident functional disability, with a focus on functional muscle mass as the underlying determinant

  2. President Award

    2026/03　University of Tsukuba

  3. Sports Research Innovator

    2026/02　University of Tsukuba

  4. 優秀発表

    2024/02　日本体育測定評価学会　筋の質指標であるPhase Angleは高齢者の要介護化を予測できるか？

Papers 14

  1. Extracellular water may increase with age and be independently and negatively associated with muscle strength and physical function in older adults: A cross‐sectional study Peer-reviewed

    Yujiro Asano, Tsukasa Yoshida, Kenji Tsunoda, Keiichi Yokoyama, Yuya Watanabe, Yasuko Yoshinaka, Tomohiro Okura, Misaka Kimura, Yosuke Yamada

    Physiological Reports　2026/06

    DOI： 10.14814/phy2.70931 　

  2. Relationship between bioelectrical impedance-derived muscle quality and physical activity, sedentary behavior, or sleep using compositional data analysis (CoDA). International-journal Peer-reviewed

    Yujiro Asano, Motohiko Miyachi, Hinako Nanri, Haruka Murakami, Yuko Gando, Takashi Nakagata, Tsukasa Yoshida, Tomohiro Okura, Yosuke Yamada

    Scientific reports　15　(1)　44108-44108　2025/12/18

    DOI： 10.1038/s41598-025-27953-3 　

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    The association between exercise behaviors-including physical activity (PA), light-intensity PA (LPA), moderate-to-vigorous-intensity PA (MVPA), sedentary behavior (SB), and sleep-and muscle quality remains unclear. This study aimed to examine the association between 24-h movement behaviors and muscle quality, as assessed by bioelectrical impedance spectroscopy (BIS). A total of 294 participants were enrolled in the cross-sectional study. LPA, MVPA, and SB were objectively measured using a tri-axial accelerometer. Sleep duration was assessed through a validated self-reported questionnaire. Muscle quality, based on electrical properties, was evaluated using a BIS device including parameters such as phase angle, intracellular-to-extracellular water ratio, membrane capacitance, characteristic frequency. Associations between 24-h movement behaviors and muscle quality derived from electrical properties were examined using compositional multiple linear regression. Additionally, hypothetical time reallocations among different movement behaviors in relation to muscle quality were evaluated using compositional isotemporal substitution. The same analyses were also conducted among participants classified as non-regular exercisers. Longer durations of MVPA were significantly associated with better indicators of muscle quality. Theoretical time reallocation analyses suggested that 30 min from SB, LPA, or sleep to MVPA was associated with approximately 0.5-3.8% higher values of BIS-derived muscle quality indices. This association remained consistent among non-regular exercisers. These cross-sectional findings indicate that greater daily MVPA is associated with a more favorable BIS-derived muscle-quality profile. MVPA is a key component of daily movement that contributes to the maintenance and potential improvement of muscle quality, as evaluated through electrical properties measured using BIS in both regular and non-regular exercisers.

  3. Segmental validation of the 50-kHz phase angle as a valid, practical proxy that closely approximates the characteristic-frequency phase angle and associations with muscle function and body water: A cross-sectional study Peer-reviewed

    Yujiro Asano, Tsukasa Yoshida, Kenji Tsunoda, Keiichi Yokoyama, Yuya Watanabe, Yasuko Yoshinaka, Tomohiro Okura, Misaka Kimura, Yosuke Yamada

    Clinical Nutrition ESPEN　70　263-273　2025/12

    Publisher: Elsevier BV

    DOI： 10.1016/j.clnesp.2025.09.030 　

    ISSN： 2405-4577

  4. Association of bioimpedance‐derived parameters with pulse wave velocity: Phase angle, extracellular to intracellular water ratio, and body cell mass Peer-reviewed

    Yujiro Asano, Motohiko Miyachi, Hinako Nanri, Haruka Murakami, Yuko Gando, Takashi Nakagata, Tsukasa Yoshida, Tomohiro Okura, Yosuke Yamada

    Physiological Reports　13　(17)　2025/09/10

    Publisher: Wiley

    DOI： 10.14814/phy2.70548 　

    ISSN： 2051-817X

    eISSN： 2051-817X

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    Abstract This study investigated the association between parameters derived from bioelectrical impedance spectroscopy (BIS) and arterial stiffness, as measured using carotid–femoral pulse wave velocity (cfPWV) and brachial‐ankle pulse wave velocity (baPWV) pulse wave velocities. Data from 292 Japanese adults were analyzed. BIS was used to assess the phase angle (PhA), extracellular water to intracellular water ratio (ECW/ICW), and body cell mass‐to‐free fat mass ratio (BCM/FFM). cfPWV and baPWV were measured using an Omron‐Colin device. Multiple linear regression analyses were conducted to examine the associations between BIS parameters and pulse wave velocity, adjusting for age, sex, height, smoking status, history of chronic diseases, and objectively measured physical activity. The results revealed that lower PhA, higher ECW/ICW, and lower BCM/FFM were significantly associated with higher cfPWV, independent of potential confounders. These associations remained significant even after adjusting for appendicular lean mass index. However, no significant associations were found between the BIS parameters and baPWV after controlling for covariates. These findings suggest that BIS‐derived parameters reflecting cellular health and body composition are associated with increased arterial stiffness in the central arteries, independent of muscle mass. This association may partly explain the relationship between these parameters and mortality, thereby highlighting the importance of BIS assessment in health promotion. However, future longitudinal studies are needed to confirm these findings.

  5. Association of Muscle Mass, Muscle Quality, and Function with Mortality in Community-Dwelling Older Adults: Focus on Segmental Phase Angle and Extracellular to Intracellular Water Ratio Peer-reviewed

    Yujiro Asano, Kenji Tsunoda, Koki Nagata, Namhoon Lim, Taishi Tsuji, Kyohei Shibuya, Tomohiro Okura

    Clinical Nutrition ESPEN　70　240-248　2025/09

    Publisher: Elsevier BV

    DOI： 10.1016/j.clnesp.2025.09.022 　

    ISSN： 2405-4577

  6. Sex- and age-related declines in muscle mass, strength, physical performance, and muscle quality among community-dwelling older adults: A cross-sectional study Peer-reviewed

    Yujiro Asano, Tsukasa Yoshida, Kenji Tsunoda, Keiichi Yokoyama, Yuya Watanabe, Yasuko Yoshinaka, Tomohiro Okura, Misaka Kimura, Yosuke Yamada

    Experimental Gerontology　112862-112862　2025/08

    Publisher: Elsevier BV

    DOI： 10.1016/j.exger.2025.112862 　

    ISSN： 0531-5565

  7. Segmental phase angle and the extracellular to intracellular water ratio are associated with functional disability in community-dwelling older adults: A follow-up study of up to 12 years Peer-reviewed

    Yujiro Asano, Kenji Tsunoda, Koki Nagata, Namhoon Lim, Taishi Tsuji, Kyohei Shibuya, Tomohiro Okura

    Nutrition　133　112709-112709　2025/05

    Publisher: Elsevier BV

    DOI： 10.1016/j.nut.2025.112709 　

    ISSN： 0899-9007

  8. Segmental extracellular-to-intracellular water resistance ratio and physical function in older adults Peer-reviewed

    Yujiro Asano, Taishi Tsuji, Tomohiro Okura

    Experimental Gerontology　181　2023/10

    DOI： 10.1016/j.exger.2023.112278 　

  9. Association of 24-h movement behaviors with phase angle in community-dwelling older adults: a compositional data analysis Peer-reviewed

    Yujiro Asano, Koki Nagata, Kyohei Shibuya, Yuya Fujii, Naruki Kitano, Tomohiro Okura

    Aging Clinical and Experimental Research　35　1469-1476　2023/05

    DOI： 10.1007/s40520-023-02425-8 　

  10. Cross‐sectional and longitudinal study of the relationship between phase angle and physical function in older adults Peer-reviewed

    Yujiro Asano, Taishi Tsuji, Mijin Kim, Koki Nagata, Kyohei Shibuya, Korin Tateoka, Tomohiro Okura

    Geriatrics & Gerontology International　23　(2)　121-147　2023/02

    DOI： 10.1111/ggi.14532 　

  11. Dose-response Association between Hand Dexterity and Functional Disability: A Longitudinal Study from the Kasama Study. International-journal

    Namhoon Lim, Kenji Tsunoda, Jaehoon Seol, Yujiro Asano, Koki Nagata, Taishi Tsuji, Keisuke Fujii, Yuya Fujii, Kaori Teraoka, Tomohiro Okura

    Annals of geriatric medicine and research　2025/09/08

    DOI： 10.4235/agmr.25.0075 　

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    BACKGROUND: Poor hand dexterity may increase the risk of functional disability; however, few studies have examined the relationship between hand dexterity and incident functional disability. The aim of this study was to prospectively investigate the dose-response association of hand dexterity with incident functional disability in community-dwelling older adults. METHODS: This study included 1,069 older adults aged ≥65 years in Kasama City, Japan. Peg-moving and circle-drawing tasks were used to evaluate hand dexterity. Functional disability was identified using the Japanese Long-Term Care Insurance System database. Restricted cubic spline analysis was performed to investigate the dose-response association between hand dexterity and incident functional disability. RESULTS: During a mean follow-up of 8.5 years (maximum 14.0 years), 248 participants (23.2%) developed functional disability. The lowest performance group in each hand dexterity test had a significantly higher risk of functional disability than the highest performance group (peg-moving: HR = 1.92, 95% CI = 1.29-2.87; circle drawing: HR = 1.66, 95% CI = 1.15-2.41). Spline analysis confirmed curvilinear dose-response associations between hand dexterity and incident functional disability. Increased risk was observed when participants performed worse than the cut points (peg-moving: 37.9/38.0 seconds; circle drawing: 21/20 points), and no decreased risk was observed for those who performed better than these cut points. CONCLUSION: Easily evaluated hand dexterity tests may be valuable for predicting functional disability in older adults. Curvilinear dose-response associations suggest that maintaining adequate hand dexterity could be a key strategy to support functional independence.

  12. A neural network approach to sarcopenia prediction based on bioelectrical impedance in community-dwelling older adults. International-journal

    Kyohei Shibuya, Yujiro Asano, Koki Nagata, Taishi Tsuji, Kotaro Kawajiri, Tomohiro Okura

    PloS one　20　(11)　e0335601　2025

    DOI： 10.1371/journal.pone.0335601 　

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    This study aimed to apply a neural network to raw bioelectrical impedance analysis data and to test whether sarcopenia could be predicted with high accuracy. The study population comprised 727 community-dwelling older adults aged 65-85 years who participated in the Kasama Study from 2015 to 2018. Sarcopenia was determined using the standard values set by the Asian Working Group for Sarcopenia 2019. Skeletal muscle mass index, grip strength, and five-times sit-to-stand test (Dataset 1) or skeletal muscle mass index, grip strength, and gait speed (Dataset 2) were used. The characteristic variables were sex, age, height, and body mass index, as well as parameters from bioelectrical impedance analysis, such as reactance, resistance, and impedance for six frequencies (1, 5, 50, 250, 500, and 1000 kHz) in six body parts measured using a multi-frequency body composition analyzer (MC-980A, Tanita). For analysis, a neural network was used to construct a model. For verification of the model's accuracy, a receiver operating characteristic analysis was performed to calculate the sensitivity, specificity, area under the curve, and positive and negative predictive values. Among the participants analyzed, 21 (3.3%) in Dataset 1 and 24 (3.7%) in Dataset 2 had sarcopenia. In Dataset 1, the model that used 5, 50, and 250 kHz showed the highest prediction accuracy (sensitivity: 1.00, specificity: 0.91, area under the curve: 0.96, accuracy: 0.91, positive predictive value: 0.28, negative predictive value: 1.00). In Dataset 2, the model that used 50 kHz exhibited the highest prediction accuracy (sensitivity: 0.91, specificity: 0.84, area under the curve: 0.88, accuracy: 0.84, positive predictive value: 0.17, negative predictive value: 1.00). In conclusion, highly accurate predictions are possible by applying a neural network to the raw data obtained from bioelectrical impedance analysis. As a highly accurate sarcopenia screening method, it is expected to be used in various settings, ranging from clinical practice to local communities.

  13. Developing a battery of physical performance tests to predict functional disability in Japanese older adults: A longitudinal study from the Kasama study.

    Namhoon Lim, Kenji Tsunoda, Koki Nagata, Yujiro Asano, Jaehoon Seol, Takashi Jindo, Taishi Tsuji, Tomohiro Okura

    Geriatrics & gerontology international　2024/10/29

    DOI： 10.1111/ggi.15008 　

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    AIM: Preventing functional disability benefits the quality of life of older adults and mitigates the economic burden of an aging society. However, the most effective physical performance tests and optimal cut points for identifying older adults at risk of functional disability remain unclear, and Japan lacks physical function-based assessment tools. We aimed to identify the physical performance tests related to functional disability and to develop a predictive test battery for it. METHODS: We included 975 older adults (mean 72.8 ± 5.2 years, 55.4% women) in Kasama City, Japan. Functional disability was defined as certification of care level 2 or above based on the long-term care insurance system. Cox proportional hazards analysis examined the association between physical performance tests and incident functional disability. RESULTS: During a mean follow-up of 8.6 years (maximum 14 years), 236 participants (24.2%) developed functional disability. After adjusting for covariates, higher performances in grip strength, single-leg balance with eyes open (SLB), timed up-and-go (TUG), five-repetition sit-to-stand (5-STS), and 5-m habitual walk were significantly associated with a lower risk of functional disability. In a stepwise model, SLB, TUG, and 5-STS were key predictors of functional disability. Receiver operating characteristic analysis determined optimal cut points of 32.6/32.7 s for SLB, 6.5/6.6 s for TUG, and 7.8/7.9 s for 5-STS. We developed a predictive battery combining these cut points (area under the curve = 0.78). CONCLUSIONS: The developed battery of physical performance tests predicts future functional disability and is useful for screening older adults at high risk. Geriatr Gerontol Int 2024; ••: ••-••.

  14. 質問紙で調査した地域在住高齢者の身体活動 かさまスタディ

    大藏 倫博, 神藤 隆志, 角田 憲治, 北濃 成樹, 相馬 優樹, 藤井 啓介, 藤井 悠也, 阿部 巧, 永田 康喜, 尹 之恩, 佐藤 文音, 薛 載勲, 徳永 智史, 林 だん勲, 浅野 優次郎, 辻 大士

    運動疫学研究: Research in Exercise Epidemiology　24　(2)　138-139　2022/12

    Publisher: 日本運動疫学会

    ISSN： 1347-5827

    eISSN： 2434-2017

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Books and Other Publications 1

  1. 体育の科学 76巻6月号「バイオメカニクス研究を切り拓く最新技術−身体をどう測り，どう読み解くか−」

    杏林書院　2026/06

Presentations 14

  1. Vertical-jump-defined powerpenia in community-dwelling older adults: a multi-indicator comparison of age-related decline and prediction of incident functional disability, with a focus on functional muscle mass as the underlying determinant

    Yujiro Asano, Tsukasa Yoshida, Keiichi Yokoyama, Yuya Watanabe, Yasuko Yoshinaka, Misaka Kimura, Yoshinobu Sato, Yoshito Otake, Masashi Taniguchi, Toru Morihara, Hiroyuki Fujita, Yui Nakayama, Mazen Soufi, Keisuke Uemura, Masaki Takao, Yosuke Yamada

    Powerpenia Conference 2026　2026/07/03

  2. Muscle composition as a key determinant of muscle power decline in older adults Invited

    Yujiro Asano, Yosuke Yamada

    Powerpenia Conference 2026　2026/07/03

  3. 個人・仲間との運動が健康寿命と不健康期間 与える影響の定量化：連続時間多状態マルコフモデル

    浅野優次郎, 渋谷恭平, 角田憲治, 永田康喜, 林湳勳, 憨娜, 大藏倫博

    第27回日本健康支援学会年次学術大会　2026/03/07

  4. CT-based muscle density analysis of individual lower-limb muscles: relationships with aging, strength, and physical function

    Yujiro Asano, Tsukasa Yoshida, Yoshinobu Sato, Yoshito Otake, Masashi Taniguchi, Tooru Morihara, Hiroyuki Fujita, Misaka Kimura, Yui Nakayama, Mazen Soufi, Keisuke Uemura, Masaki Takao, Keiichi Yokoyam, Tempei Tominaga, Tomohiro Okura, Yosuke Yamad

    16th Edition, 2026, Intrinsic Capacity, Frailty and Sarcopenia Research Conference for Healthy Longevity (ICFSR 2026)　2026/02/12

  5. Intracellular Water Reflects Functional Muscle, While Increased Extracellular Water Is Associated with Impaired Muscle Performance

    Yujiro Asano, Tsukasa Yoshida, Keiichi Yokoyama, Yuya Watanabe, Yasuko Yoshinaka, Kenji Tsunoda, Tomohiro Okura, Misaka Kimura, Yosuke Yamada

    World Congress on Kinesiology & Sports Science　2025/10/25

  6. Age- And Sex-related Differences In Body Composition, Muscle Mass, Strength, Physical Function, Quality, And Specific Muscle Strength Community-dwelling Older Adults

    Yujiro Asano, Tsukasa Yoshida, Keiichi Yokoyama, Yuya Watanabe, Yasuko Yoshinaka, Kenji Tsunoda, Tomohiro Okura, Misaka Kimura, Yosuke Yamada

    2025 American college of sports medicine annual meeting　2025/05/29

  7. サルコペニア診断に筋質評価を組み込む有用性：GLIS定義を踏まえた新たなアプローチ

    浅野 優次郎, 吉田司, 横山慶一, 渡邊裕也, 吉中康子, 大藏倫博, 木村みさか, 山田陽介

    第12回日本介護予防・健康づくり学会　2024/12/01

  8. Phase Angle as a Muscle Quality Indicator Predicts Mortality in Older Adults as Effectively as Function Tests

    Yujiro Asano, Kenji Tsunoda, Taishi Tsuji, Namhoon Lim, Koki Nagata, Tomohiro Okura

    The 78th Japanese Society of Physical Fitness and Sports Medicine　2024/09/03

  9. Muscle Quality Assessment via BIA and BIS: Associations with Physical Function and Physical Activity

    Yujiro Asano, Yosuke Yamada, Koki Nagata, Kyohei Shibuya, Tomohiro Okura

    International Conference on Frailty and Sarcopenia Research　2024/03/22

  10. 筋の質指標であるPhase Angleは高齢者の要介護化を予測できるか？

    浅野優次郎, 角田憲治, 辻大士, 林湳勳, 永田康喜, 渋谷恭平, 大藏倫博

    第23回日本体育測定評価学会大会　2024/02/29

  11. 生体電気インピーダンス（BIA）法で測定した細胞内外水分抵抗比率は高齢者の身体機能評価指標として有用か？

    浅野優次郎, 辻大士, 大藏倫博

    第73回日本体育・スポーツ・健康学会大会

  12. 地域在住高齢者における生体電気インピーダンスによるPhase Angleと座位行動および強度別身体活動との関連

    浅野優次郎, 辻大士, 永田康喜, 渋谷恭平, 大藏倫博

    第77回日本体力医学会大会

  13. 生体電気抵抗法で測定されるPhase Angleと高齢者の身体機能との関連

    浅野優次郎, 立岡光臨, 井上大樹, 大藏倫博

    第76回日本体力医学会大会

  14. 地域在住高齢者の余暇活動時間の長短に着目した運動実施状況と運動セルフ・エフィカシーの関係

    浅野優次郎, 藤井悠也, 大藏倫博

    第22回日本健康支援学会大会

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Research Projects 2

  1. Exploring Brain and Muscle Contributions to Physical Function Decline in Older Adults

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for JSPS Fellows

    Institution: Tohoku University

    2026/04 - 2029/03

  2. 高齢者におけるPhase Angleの健康予測指標の可能性および向上方法の検討 Competitive

    浅野優次郎

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業 特別研究員奨励費

    2023/04 - 2026/03