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Effects of polyphenols on skeletal muscle cells and underlying molecular mechanisms
( Koichi Nakazato ),( Aratatsutaki ),( Seok Ki Min ) 한국운동영양학회 2012 Physical Activity and Nutrition (Phys Act Nutr) Vol.16 No.3
Polyphenols are chemical compounds characterized by multiple phenolic hydroxyl groups. The aim of this review is to summarize the effects of polyphenols on skeletal muscle tissues with regard to the following three points: (1) up-regulation of oxidative properties via activation of AMP-activated kinase (AMPK), (2) prevention of necrosis of muscle tissue by suppression of tumor necrosis factor α (TNF-α) and necrosis factor kappa B (NF-κB) activity, and (3) enhancement of muscular function by proliferator gamma co-activator (PGC) -1α and AMPK. Although most of the studies are limited to cell cultures and experimental animal trials, and further studies are needed in human subjects, there is every indication that polyphenols are a beneficial supplementation for athletes.
Invited Review : Clinical and Basic Studies of Muscle Strain Injury
( Koichi Nakazato ),( Kih Yok Lee ),( Karina Kouzaki ),( Kenji Hiranuma ),( Seok Ki Min ),( Eisuke Ochi ),( Hong Sun Song ) 한국스포츠정책과학원(구 한국스포츠개발원) 2013 International Journal of Applied Sports Sciences Vol.25 No.1
In this review, we gleaned clinical and basic studies of muscle strain injury. In clinical situation, thigh muscles, especially hamstrings, are frequently suffered. Sudden eccentric contraction (EC), imbalance of muscle strength, preexisting strain injuries are significant risk factors. Magnetic resonance and ultrasonography imaging provides useful information for diagnosis and care. Atrophy and scar formation can be raised as characteristics in chronic change. Despite of these information, definition and classification for strain injury is still under development. In basic aspect, EC-induced muscle damage is frequently used as a muscle strain injury model. With in vivo EC model, we showed that (1) cellular myogenic events are associated with torque recovery after EC-induced muscle injury, (2) muscle protein degradation is induced by severe ECs. To reproduce unique events in muscle strain injury, such as muscle atrophy, fibrosis and recurrence, is a key to simulate muscle strain injury in animal and human models.
( Naoki Kikuchi ),( Koichi Nakazato ) 한국운동영양학회 2015 Physical Activity and Nutrition (Phys Act Nutr) Vol.19 No.3
Training variants (type, intensity, and duration of exercise) can be selected according to individual aims and fitness assessment. Recently, various methods of resistance and endurance training have been used for muscle hypertrophy and VO2max improvement. Although several genetic variants are associated with elite athletic performance and muscle phenotypes, genetic background has not been used as variant for physical training. ACTN3 R577X is a well-studied genetic polymorphism. It is the only genotype associated with elite athletic performance in multiple cohorts. This association is strongly supported by mechanistic data from an Actn3-knockout mouse model. In this review, possible guidelines are discussed for effective utilization of ACTN3 R577X polymorphism for physical training.
Association between Asporin gene and lumbar disc degeneration in Japanese collegiate athletes
( Min Seok-ki ),( Nakazato Koichi ),( Hiranuma Kenji ),( Kim Tae-whan ) 한국체육대학교 체육과학연구소 2017 스포츠사이언스 Vol.35 No.1
Recently, aspartic acid (D)-repeat of the asporin (ASPN) gene was shown to be associated with lumbar disc degeneration in Asian population. Our objective was to test whether the D-repeat polymorphism was associated with lumbar disc degeneration (LDDG) in Japanese collegiate athletes. We determined ASPN polymorphism amongst 516 trained collegiate athletes (341 men, 175 women, experience 8.5±3.5) from 7 different sports. We separated FAM-labeled polymerase chain reaction (PCR) products containing the D-repeat polymorphism of ASPN by size. LDDG was evaluated based on the signal intensity of T2-weighted magnetic resonance imaging. By using logistic regression analysis concomitant with interaction term and the Wald tests, D14 allele of the ASPN gene was associated with an increased risk of LDDG in collegiate athletes (Odds ratio (OR); 2.14, 95% confidence interval (CI); 1.1-4.18, P=0.025). Also, the D13 allele is under-represented in collegiate athletes with LDDG (OR; 1.86, 95% CI; 1.16-2.98, P=0.009). However, ASPN polymorphism was not a risk factor for female collegiate athletes. We concluded that the ASPN gene is a significant risk factor for LDDG occurrence in Japanese collegiate male athletes.
Calcaneal quantitative ultrasound analysis in korean and japanese elite female athletes
송홍선,민석기,Hideaki Ishigami,이기혁,Harlisa Rozikin,Koichi Nakazato 국민체육진흥공단 한국스포츠정책과학원 2017 International Journal of Applied Sports Sciences Vol.29 No.2
The relationships between bone properties and cumulative mechanical impact were examined in elite female athletes (N=70) and age, gender matched non-athlete controls (N=64). The athletes were divided into 3 groups, namely, high-impact (HI: body weight bearing with high mechanical loading, N=18), medium-impact (MI: body weight bearing with medium load, N=36), and low-impact (LI: body weight bearing with low load, N=16). Effects of mechanical impact on quantitative ultrasonography (QUS) parameters, including speed of sound (SOS), broadband ultrasound attenuation (BUA), and stiffness index (SI), were assessed using a multiple linear regression model adjusted for age, body weight, height, body mass index, and impact. We found that BUA was positively influenced by MI (P < 0.05). SOS was negatively influenced by LI (P < 0.05). SI was positively influenced by MI (P < 0.05). In conclusion, the bone qualities in elite female athletes differ depending on their cumulative impacts.