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Naokata Ishii / Professor / Division of Environmental Studies
Department of Human and Engineered Environmental Studies / / Exercise Physiology and Biochemistry
http://www.c.u-tokyo.ac.jp/info/research/faculty/list/mds/mds-ls/f002506.html

Career Summary
1977: Graduated from Faculty of Science, University of Tokyo
1982: Received Ph.D. from University of Tokyo
1982: Research associate, University of Tokyo
1987-88: JSPS International Research Fellow, Oxford University
1991: Associate Professor, University of Tokyo
1999-Present: Professor, University of Tokyo
Educational Activities
Graduate school: Physiological Science of Adaptation
Research Activities

Mechanisms of catch contraction in smooth muscles (1982-91):
The cellular and subcellular mechanisms underlying the catch contraction of smooth muscles were studied by using isolated smooth muscle cells. By measuring tension and intracellular free-calcium concentration simultaneously, we found that free calcium was returned to its resting level even during the maintenance of contractile force (ref 1). In addition, 31-P nuclear magnetic resonance measurements showed that the level of ATPase activity of the actin-myosin cross-bridges was as low as its resting level (ref. 2).

Studies on muscle contraction that used isolated myofilaments (1990-98):
We developed an in vitro model of muscle contraction that consisted of single thick filaments isolated from muscles and polymerized actin cables. By measuring the fine forces generated between the thick and actin filaments, we demonstrated that weak interactions can occur between myosin and actin with mismatched polarities (ref 3), and that increases in sliding velocity that are greater than the unloaded velocity (Vmax) occurred when a negative load was applied (ref 4).

Resistance training with restriction of muscular blood flow (1995-2011):
We found that resistance training even with low intensity and small exercise volume can increase muscular size and strength when performed under venous blood flow restriction (ref 5). Subcellular and genetic mechanisms underlying these effects were studied by using animal models (ref 6 and 7).

Basic and applied studies on slow-resistance training (2005-Present):
Based on the mechanisms of resistance training with blood flow restriction (mentioned above), we developed a low-intensity resistance training program with slow movement and tonic force generation (LST method), which was regarded as safer and more accessible than resistance training with blood flow restriction (ref 8). Studies on its mechanism (ref 9) and applications in elderly and frail subjects (ref 10 and 11) have been conducted.

Novel methodologies for evaluation of muscular function in vivo (1995-Present):
To measure the maximal unloaded velocity of contracting muscle in the human body, we developed an in vivo slack test by modifying the methodology used for single muscle fibers (ref 12). In addition, a servo-controlled multi-joint dynamometer was newly developed (ref 13) and applied in the evaluation of lower limb function in the elderly (ref 14). Recently, contractile forces in the human body have been estimated by measuring the propagation velocity of the ultrasonic shear wave along the longitudinal axis of the muscle fibers (ref 15).

Motion analyses with wearable sensors (2011-Present):
Running and walking movements have been analyzed by using wearable inertial sensors attached to various portions of the body (ref 16). In particular, walking movement is analyzed in order to construct a system for early detection of the risk of falling and/or frailty in the elderly.

Literature

1) Ishii, Simpson and Ashley: Free calcium at rest during "catch" in single smooth muscle cells. Science (N.Y.), 243, 1367-1368, 1989.
2) Ishii, Mistumori and Takahashi: Changes in sarcolpasmic metabolite concentrations and pH associated with the catch contraction and relaxation of the anterior byssus retractor muscle of Mytilus edulis measured by phisphorus-31 nuclear magnetic resonance. J. Musc. Res. Cell Motil., 12, 242-246, 1991.
3) Yamada, Ishii and Takahashi: Direction and speed of actin filaments moving along thick filaments isolated from molluscan smooth muscle. J. Biochem., 108, 341-343, 1990.
4) Ishii, Tsuchiya and Sugi: An in vitro motility assay system retaining steady-state force-velocity characteristics of muscle fibers under positive and negative loads. Biochim. Biophys. Acta., 1319, 155-162, 1997.
5) Takarada, Sato, Takebayashi, Takazawa, Tanaka and Ishii: Effects of low-intensity resistance exercise combined with vascular occlusion on muscular function in humans. J. Appl. Physiol., 88, 2097-2106, 2000.
6) Kawada and Ishii: Skeletal muscle hypertrophy after chronic restriction of venous blood flow in rats. Med. Sci. Sports Exerc., 37, 1144-1150, 2005.
7) Ishii, Ogasawara, Kobayashi and Nakazato: Roles played by protein metabolism and myogenic progenitor cells in exercise-induced muscle hypertrophy and their relation to resistance training regimens. J. Phys. Fitness Sports Med., 1, 83-94, 2012.
8) Tanimoto and Ishii: Effects of low-intensity resistance exercise with slow movement and tonic force generation on muscular function in young men. J. Appl. Physiol., 100, 1150-1157, 2006.
9) Ochi, Hirose, Hiranuma, Min, Ishii and Nakazato: Elevation of myostatin and FOXOs in prolonged muscular impairment induced by eccentric contractions in rat medial gastrocnemius muscle. J. Appl. Physiol., 108, 306-313, 2010.
10) Watanabe, Tanimoto, Ohkane, Miyachi and Ishii: Low-intensity resistance exercise with slow movement and tonic force generation increases muscle size and strength in older adults. J. Aging Phys. Activity, 21, 71-84, 2013.
11) Watanabe, Madarame, Ogasawara, Nakazato and Ishii: Effect of very low-intensity resistance training with slow movement on muscle size and strength in healthy older adults. Clinl Physiol. Funct. Imaging, 34, 463-470, 2014.
12) Sasaki and Ishii: Shortening velocity of human triceps surae muscle measured with the slack test in vivo. J. Physiol., 567, 1047-56, 2005.
13) Yamauchi, Mishima, Fujiwara, Nakayama and Ishii: Steady-state force-velocity relation in human multi-joint movement determined with force clamp analysis. J. Biomech., 40, 1433-1442, 2007.
14) Yamauchi, Mishima, Nakayama and Ishii: Ageing related differences in maximum force, unloaded velocity and power of human leg multi-joint movement. Gerontology, 56, 167-174, 2010.
15) Sasaki, Toyama and Ishii: Length-force characteristics of in vivo human muscles reflected by supersonic shear imaging. J. Appl. Physiol.,117, 153-62, 2014.
16) Kawabata, Goto, Fukuzaki, Sasaki, Hihara and Ishii: Acceleration patterns in the lower and upper trunk during running. J. Sport Sci., 31, 1841-1853, 2013.
Other Activities
Japanese Society of Physical Fitness and Sports Medicine
Japanese Society of Physical Education
Japanese Society of Exercise Physiology
Japanese Society of Biophysics
Editor in Journal of Physical Fitness and Sports Medicine
Vise Chairman of Japan Bodybuilding and Fitness Federation
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Future Plan
In the other laboratory of the Department of Life Sciences, Komaba, we are conducting studies on the basic mechanisms of exercise training by using mainly animal models. Based on knowledge acquired from these basic studies, we are planning to construct in the Kashiwa Laboratory a novel system for evaluating and improving physical functions of the elderly.
Messages to Students
Real innovations with strong originality should be inspired by various experiences. Therefore, studying eagerly various subjects regardless of your discipline is important for your academic development. The Department of Frontier Sciences will provide you with a good environment where you can experience various studies ranging from exercise training to development of new electronic devices.
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