Satoshi Fujita

Ritsumeikan University · College of Sport and Health Science

Leucine is a branched-chain amino acid that is present in protein, and it is an essential factor in activating the mechanistic target of the rapamycin complex 1 signaling pathway and increasing muscle protein synthesis. However, the loss of digestive function after total gastrectomy leads to impaired protein absorption, potentially failing to stimu...

Higher fat-to-muscle mass ratio (FMR) is reported to be a risk factor for various diseases, including type 2 diabetes and cardiovascular diseases, and mortality. Although this association suggests that reducing FMR may help to prevent certain diseases and mortality, the relationship between FMR and lifestyle factors is unclear. Therefore, we perfor...

Skeletal muscle mass is critical for activities of daily living. Resistance training maintains or increases muscle mass, and various strategies maximize the training adaptation. Mesenchymal stem cells (MSCs) are multipotent cells with differential potency in skeletal muscle cells and the capacity to secrete growth factors. However, little is known...

TRPM8 agonist has been reported to promote osteogenic differentiation of mesenchymal stem cells (MSCs), therefore we evaluated whether cooling‐induced activation of TRPM8 promotes myogenic differentiation of MSCs. We used 5‐azacytidine as a myogenic differentiation inducer in murine bone marrow‐derived MSCs. Addition of menthol, a TRPM8 agonist, to...

Higher fat-to-muscle mass ratio (FMR) is reported to be a risk factor for various diseases, including type 2 diabetes and cardiovascular diseases, and mortality. Although this association suggests that reducing FMR may help to prevent certain diseases and mortality, the relationship between FMR and lifestyle factors is unclear. Therefore, we perfor...

Aerobic training (AT) is suggested to be an effective anti-aging strategy for skin aging. However, the respective effects of resistance training (RT) have not been studied. Therefore, we compared the effects of AT and RT on skin aging in a 16-week intervention in 61 healthy sedentary middle-aged Japanese women. Data from 56 women were available for...

Aerobic training (AT) is suggested to be an effective anti-aging strategy for skin aging. However, the respective effects of resistance training (RT) have not been studied. Therefore, we compared the effects of AT and RT on skin aging in a 16-week intervention in 61 healthy sedentary middle-aged Japanese women. Data from 56 women were available for...

The aim of this study was to investigate the effects of increased dietary protein in daily-life settings in Japan for 6 months on the activities of daily living (ADL) in adults aged 75 or older at nutritional risk. The study was an open-label, exploratory, randomized controlled trial conducted at seven hospitals in Japan. The study participants wer...

Mounting evidence links Type 1 diabetes (T1D) with cognitive dysfunction, psychiatric disorders, and synaptic alterations; however, the underlying mechanism remains unclear. Numerous synaptic proteins and synaptic adhesion molecules (SAMs) that orchestrate synaptic formation, restructuring, and elimination are essential for proper brain function. C...

Sleep quality (duration, efficiency, and latency) is directly associated with human health. An interventional study reported that the time of dinner influenced sleep latency, suggesting that it may also be associated with other sleep quality indices under free-living conditions. Therefore, we cross-sectionally examined the association between the t...

Substantial evidence suggests an important role of liver function in brain health. Liver function is clinically assessed by measuring the activity of hepatic enzymes in the peripheral blood. Brain-derived neurotrophic factor (BDNF) is an important regulator of brain function. Therefore, we hypothesized that blood BDNF levels are associated with liv...

Purpose This study investigates if co-ingestion of cluster dextrin (CDX) augments the appearance of intrinsically labeled meat protein hydrolysate-derived amino acid (D 5 -phenylalanine), Akt/mTORC1 signaling, and myofibrillar protein fractional synthetic rate ( FSR). Methods Ten moderately trained healthy males (age: 21.5 ± 2.1 years, body mass:...

Muscle atrophy and sarcopenia (the term given to the age-related decline in muscle mass and function), influence an individuals risk of falls, frailty, functional decline, and, ultimately, impaired quality of life. Vitamin D deficiency (low serum levels of 25-hydroxyvitamin D (25(OH)D3)) has been reported to impair muscle strength and increase risk...

Objective To observe the relationship of the protein intake at each meal and daily total with change in lean tissue mass with progressive resistance exercise training (RET) in healthy middle-aged women. Research Methods & Procedures Twenty-two healthy Japanese women were recruited from Shiga Prefecture, Japan, and a supervised whole-body RET progr...

Objective The major purpose of this study was to determine the specific muscle(s) for superior sprint performance in sprinters. The cross sectional areas (CSAs) of ten muscles of the trunk and lower limb were measured using magnetic resonance images in 56 male sprinters and 40 male non-sprinters. In addition to the absolute CSA, to minimize the eff...

Vascular endothelial function deteriorates with age and disease, and the production of vasodilator factors like nitric oxide (NO) decreases. The free amino acid l-citrulline increases vasodilation and blood flow through increased NO production. We examined the effects of oral l-citrulline administration on vascular delivery of substances to skeleta...

Purpose: We previously reported that the cross-sectional area of the quadriceps femoris is correlated with the sprint performance of preadolescent sprinters. This finding suggests a close relationship between knee extensor torque-enhancing morphology and sprint performance in this young population. To further clarify this issue, in this study, we...

Skeletal muscle mass is critical for good quality of life. Mesenchymal stem cells (MSCs) are multipotent stem cells distributed across various tissues. They are characterized by the capacity to secrete growth factors and differentiate into skeletal muscle cells. These capabilities suggest that MSCs might be beneficial for muscle growth. Nevertheles...

Sarcopenia, an age-related reduction in skeletal muscle mass and strength, is mainly caused by chronic inflammation. Because mesenchymal stem cells (MSCs) have the capacity to both promote myogenic cell differentiation and suppress inflammation, they are a promising candidate for sarcopenia treatment. In this study, to achieve the long-term retenti...

Loss of appetite in the summer season leads to weight reduction, which subsequently affects sports performance. We investigated this issue in 94 high school freshmen baseball players at four high schools. The participants were divided into two groups: RICE (n＝38), receiving nutritional education with provision of rice; CON (n＝56), receiving nutriti...

Insufficient duration of recovery between resistance exercise bouts reduces the effects of exercise training, but the influence on muscle anabolic responses is not fully understood. Here, we investigated the changes in the distribution of eukaryotic initiation factor (eIF) 4E, a key regulator of translation initiation, and related factors in mouse...

Inactivity leads to skeletal muscle atrophy, whereas intermittent loading (IL) during hind limb unloading (HU) attenuates muscle atrophy. However, the combined effects of IL and protein supplementation on disuse muscle atrophy are unclear. Therefore, we investigated the effects of IL and a high-protein oral nutritional supplement (HP) during HU on...

The joint moment arm (MA) dimension is related to joint torque in adults. However, this relationship remains unexplored in children. In this study, we aimed to determine the relationship between MA and joint torque of the knee extensors in this young population. The quadriceps femoris muscle volume (MV) and knee extensor MA in 20 preadolescent boys...

Resistance exercise transiently activates anabolic and catabolic systems in skeletal muscle. Leucine-enriched essential amino acids (LEAAs) are reported to stimulate the muscle anabolic response at a lower dose than whey protein. However, little is known regarding the effect of LEAA supplementation on the resistance exercise-induced responses of th...

Abtract The vitamin D pathway is related to the mass and function of skeletal muscles. Several studies have demonstrated the role of vitamin D receptor (VDR) and CYP27B1 in skeletal muscles, suggesting that these proteins may regulate skeletal muscles and their function. However, it remains unclear whether the expression of VDR and CYP27B1 is modif...

The mitochondrial translation process, in which mitochondrial DNA (mtDNA)-encoded genes are translated into their corresponding proteins, is crucial for mitochondrial function, biogenesis, and integrity. This process is divided into four phases—initiation, elongation, termination, and mitoribosome recycling—which are regulated by specific translati...

Acute aerobic exercise (AE) increases skeletal muscle insulin sensitivity for several hours, caused by acute activation of AMP-activated protein kinase (AMPK). Acute resistance exercise (RE) also activates AMPK, possibly improving insulin-stimulated glucose uptake. However, RE-induced rapamycin-sensitive mechanistic target of rapamycin complex 1 (m...

Skeletal muscle disuse rapidly decreases muscle mass. Resistance training (RT) is believed as the most effective way to gain muscle mass via an increase in mTORC1 activity and muscle protein synthesis (MPS). However, it remains unclear whether muscle atrophy by disuse alters the mTORC1 activation and MPS response to an acute resistance exercise (RE...

Background: Although daily protein intake (PI) has been reported to be essential for regulating muscle mass, the distribution of daily PI in individuals is typically the lowest at breakfast and skewed toward dinner. Skewed protein intake patterns and inadequate PI at breakfast were reported to be negative factors for muscle maintenance. Objective...

Skeletal muscle mass is maintained by continuous muscle protein synthesis and breakdown. Food restriction augments muscle protein breakdown and consequently induces muscle mass loss. Acute bouts of resistance exercise mimicking muscle contractions (RE) attenuate fasting‐induced protein breakdown. We hypothesized that three bouts of RE (resistance t...

Background: Ursolic acid altered muscle protein metabolism in normal and resting conditions after acute resistance exercise, suggesting that eating fruits rich in ursolic acid could enhance muscle protein synthesis and decrease muscle degradation. Aronia melanocarpa, a member of the family Rosaceae and native to North America and Eastern Canada, i...

Resistance exercise (RE) activates the mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway and increases muscle protein synthesis. Severe fasting induces 5′ adenosine monophosphate‐activated protein kinase (AMPK), which attenuates mTORC1 activation. However, the effect of RE on the response of mTORC1 signaling proteins after a peri...

This study investigated the effects of a high intensity interval training (HIIT) program on both physical fitness and executive functions in children. Fifty-six children aged 8–12 years participated in this study, and were divided into a HIIT group and a control group. The HIIT group performed three sessions of the 8- to 10-min HIIT program per wee...

Skilled sprinting is fundamental in many sports, especially to improve athletic performance in youth. This study therefore aimed to investigate the effect of plyometric training on sprint performance in boys aged 9–12 years. Twenty boys were divided into a plyometric training group (n = 9) and a control training group (n = 11). In both groups, part...

Resistance exercise training induces skeletal muscle hypertrophy, but repeated bouts gradually attenuate this anabolic effect. Attenuation of mechanistic target of rapamycin complex 1 (mTORC1) activation by repetitive resistance exercise is involved in this process, but the mechanism leading to inactivation of mTORC1 remains unclear. In this study,...

Background The World Health Organization has defined life skills as, “the abilities for adaptive and positive behavior that enable individuals to deal effectively with the demands and challenges of everyday life.” Life skills in athletes can be translated as skills necessary to deal with the demands and challenges in the competition. This includes...

New findings: What is the central question of this study? Type 2 diabetes mellitus (T2DM) is known to cause skeletal muscle atrophy. However, it is not known whether T2DM affects the resistance-training (RT)-mediated molecular adaptations and subsequent muscle hypertrophy. What is the main finding and its importance? Although the skeletal muscle m...

Background Oral gamma-aminobutyric acid (GABA) supplementation increases growth hormone (GH) serum levels and protein synthesis. Therefore, post-exercise supplementation using GABA and protein may help enhance training-induced muscle hypertrophy. We evaluated whether GABA with whey protein enhanced muscular hypertrophy in men after progressive resi...

Resistance training (RT) has been known to be effective in maintaining and improving bone strength, which is based on bone mineral density (BMD) and bone quality. However, it is not clear whether RT is effective in improving bone strength in patients with type‐2 diabetes mellitus (T2DM), who have a high risk of fracture. Therefore, we tested the ef...

Protein intake of >0.24 g/kg of body weight (BW) at a single meal is necessary to maximize muscle protein synthesis in a young population. However, the association between the protein intake rate for three meals and muscle mass in the young population has not been evaluated. We hypothesized that a protein intake of >0.24 g/kg BW at all three meals...

Dietary protein intake is critical for the maintenance of skeletal muscle mass. Plasma amino acid concentrations increase with protein intake and increases in muscle protein synthesis are dependent on leucine concentrations. We aimed to investigate the effect of a mixed meal and free amino acids intake on plasma leucine concentrations. In this rand...

Introduction Skeletal muscle is an essential factor that is involved in locomotive ability as well as metabolic capacity. Skeletal muscle mass is mainly determined by net balance of muscle protein turnover (i.e. muscle protein synthesis and breakdown). Skeletal muscle mass is quickly recovered in response to resistance exercise even after prolonged...

The factors that underpin heterogeneity in muscle hypertrophy following resistance exercise training (RET) remain largely unknown. We examined circulating hormones, intramuscular hormones, and intramuscular hormone-related variables in resistance-trained men before and after 12 weeks of RET. Backward elimination and principal component regression e...

Mitochondrial function in skeletal muscle and white adipose tissue (WAT) declines with aging and the progression of type 2 diabetes and insulin resistance. Although exercise increases mitochondrial biogenesis and function in both tissues, the molecular mechanisms are not fully understood. CDGSH iron sulfur domain-containing proteins (CISDs) are a n...

The process of mitochondrial translation, in which mitochondrial (mt)DNA-encoded genes are translated into proteins, is crucial for mitochondrial function and biogenesis. In each phase, a series of mitochondrial translation factors is required for the synthesis of mtDNA-encoded mitochondrial proteins. Two mitochondrial initiation factors (mtIF2 and...

Skipping breakfast has been reported to decrease daily energy and nutrient intake. We aimed to investigate whether habitual breakfast intake frequency is associated with fat-free mass (FFM) in healthy young subjects. We hypothesized that skipping breakfast and the subsequent negative energy balance may be risk factors for reduced muscle mass. This...

The effect of remote ischemic preconditioning (RIPC) on whole‐body exercise performance and its potential mechanism remains poorly understood. In this study, we examined whether RIPC can accelerate systemic and local O2 dynamics and can enhance endurance during the work‐to‐work cycling exercise. Thirteen healthy men were instructed to perform the w...

Adapter protein containing PH domain, PTB domain, and leucine zipper motif 1 (APPL1) has been reported as a positive regulator of insulin-stimulated Akt activation. The expression of APPL1 is reduced in skeletal muscles of type 2 diabetic (T2D) animals, implying that APPL1 may be an important factor affecting insulin sensitivity. However, the regul...

Background Vitamin D and calcium are essential nutrients for bone health. In addition, vitamin D suppresses inflammatory cytokines and increases bone resorption. Therefore, improvements in bone health by calcium and vitamin D supplementation have the potential to not only improve calcium metabolism but also suppress inflammation associated with exe...

Objectives The aim of the study was to investigate the ameliorative effects of a oligomerized- polyphenol from Litchi chinensis fruit extract (OPLFE) on temporary physical fatigue in healthy track and field athletes. Previously, the benefits had been elucidated by objective assessments in the clinical study and reported, however, the subjective one...

Insulin resistance reduces insulin-induced muscle protein synthesis and accelerates muscle protein degradation. Ginseng ingestion has been reported to improve insulin resistance through the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway. We hypothesized that panaxatriol (PT) derived from ginseng in combination with aerobic exercise (EX) may...

Background When combined with exercise, dietary amino acid (AA) supplementation is an effective method for accelerating fat mobilization. However, the effects of single AAs combined with exercise on fat oxidation remains unclear. We hypothesized that consumption of a specific amino acid, L- phenylalanine, may result in the secretion of glucagon, an...

Purpose: We attempted to determine the relationships between the cross-sectional area (CSA) of the trunk and lower limb muscles and sprint performance in male preadolescent sprinters. Methods: Fifteen sprint-trained preadolescent boys (age, 11.6 ± 0.4 years) participated in this study. The CSAs of the participants' trunk and lower limb muscles w...

Previous studies have reported that different modes of muscle contraction (i.e., eccentric or concentric contraction) with similar contraction times can affect muscle proteolytic responses. However, the effect of different contraction modes on muscle proteolytic response under the same force−time integral (FTI: contraction force × time) has not bee...

Previous studies have demonstrated that an acute bout of aerobic exercise induces a subsequent delayed onset of hypoglycemia among patients with type 1 diabetes. However, the mechanisms of exercise-induced hypoglycemia in type 1 diabetes are still unclear. Streptozotocin (STZ) was injected to 6-week-old male Wistar rats, and three days after STZ in...

Raw data of present study. (XLSX)

Certification which native speaker checked English language in the manuscript. (PDF)

Insulin stimulates skeletal muscle glucose uptake via activation of the protein kinase B/Akt (Akt) pathway. Recent studies suggest that insulin down-regulates AMP-activated protein kinase (AMPK) activity via Ser485/491 phosphorylation of the AMPK α-subunit. Thus, lower blood insulin concentrations may induce AMPK signal activation. Acute exercise i...

Skeletal muscle is an essential tissue that regulates glucose metabolism and locomotive ability. Therefore, gaining skeletal muscle mass is important for maintaining or improving health as well as athletic sport performance. Over the past decade, resistance exercise has been shown to be the most effective method for gaining muscle mass. Acute resis...

During exercise, blood levels of several hormones increase acutely. We hypothesized that consumption of a specific combination of amino acids (arginine, alanine, and phenylalanine; A-mix) may be involved in secretion of glucagon, and when combined with exercise may promote fat catabolism. Ten healthy male volunteers were randomized in a crossover s...

The present study was conducted to compare bone mineral density (BMD) among long distance runners with sprinters, and to examine factors related to BMD at different bone sites among female high school track and field athletes. Thirty-seven adolescent female long distance runners (LDRs) and sprinters (SPRs) (16.1±0.8 yr old, LDR ［＞800 m］ n＝16, SPR ［...