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Taurine enhances physical performance; however, the underlying mechanism remains unclear. This study examined the effect of taurine on the overtime dynamics of blood glucose concentration (BGC) during endurance exercise in rats. Male F344 rats were subjected to transient treadmill exercise until exhaustion following 3 weeks of taurine supplementation or non-supplementation (TAU and CON groups). Every 10 min during exercise, BGC was measured in blood collected through cannulation of the jugular vein. Gluconeogenesis-, lipolysis-, and fatty acid oxidation-related factors in the plasma, liver, and skeletal muscles were also analyzed after 120-min run. Exercise time to exhaustion was significantly longer with taurine supplementation. BGC in the two groups significantly increased by 40 min and gradually and significantly decreased toward the respective exhaustion point. The decline in BGC from the peak at 40 min was significantly slower in the TAU group. The time when the once-increased BGC regressed to the 0-time level was significantly and positively correlated with exercise time until exhaustion. At the 120-min point, where the difference in BGC between the two groups was most significant, plasma free fatty acid concentration and acetyl-carnitine and N-acetyltaurine concentrations in skeletal muscle were significantly higher in the TAU group, whereas glycogen and glucogenic amino acid concentrations and G6Pase activity in the liver were not different between the two groups. Taurine supplementation enhances endurance capacity by delaying the decrease in BGC toward exhaustion through increases of lipolysis in adipose tissues and fatty acid oxidation in skeletal muscles during endurance exercise.

Background/Objective Muscle soreness and damage occurs after completing a full marathon. Here we refer to muscle soreness induced by prolonged running as early-onset muscle soreness (EOMS) because muscle soreness and damage markers induced after prolonged running are different from delayed-onset muscle soreness (DOMS) and muscle damage markers induced after eccentric contraction, such as resistance exercise. The dynamics and relationship between muscle damage markers and EOMS are unclear; therefore, in this study, we aimed to elucidate the relationship between EOMS and indirect muscle damage markers, and their dynamics after a full marathon. Methods The following measurements were performed in 19 subjects who completed a full marathon: perceived muscle soreness (using a numeric rating scale), thigh circumference (CIR), hip joint range of motion (ROM), jump height (JH) and muscle damage marker activities in the blood (CK, AST, LDH, ALD) before (Pre), after (Post) and every day for 4 days after a full marathon (D1−4). Results EOMS was induced, as determined by the numeric rating scale score peaking immediately after a full marathon. ROM and JH significantly decreased and all muscle damage markers significantly increased after a full marathon. Serum CK and AST peaked at D1. Serum LDH and ALD peaked at Post and D3. Each marker showed different dynamics. CIR significantly decreased after a full marathon. Conclusion Muscle soreness peaked and muscle damage markers in the blood showed different dynamics after a full marathon. In other words, this is different from DOMS.

PurposeCell-free DNA (cfDNA) has been investigated as a minimally invasive biomarker for many diseases, particularly cancer. An increase in cfDNA has been observed during exercise. Neutrophil extracellular traps (NETs) may be the origin of cfDNA in response to acute exercise, but the mechanisms of generation of cfDNA during exercise remain unclear. In this study we investigated the dynamics of serum and urinary cfDNA levels and determined the relevance of other biomarkers to serum and urinary cfDNA levels and fragment size after a full marathon.MethodsSamples were collected from 23 healthy male subjects. Blood and urine samples were collected before and immediately, two hours, and one day after the full marathon. The measurements included serum and urinary cfDNA, creatine kinase, myoglobin, creatinine, white blood cells, platelets, and lactoferrin from blood, and amylase, albumin, and creatinine from urine.ResultsSerum and urinary cfDNA levels increased after a full marathon. Creatine kinase, myoglobin, and creatinine in blood, and albumin and creatinine in urine also increased significantly after a full marathon. Serum cfDNA showed peak values about 180 bp after the full marathon. Values over 1000 bp were present at two hours post-marathon. Urinary cfDNA showed peak values from 35 bp to 50 bp after the full marathon. Values over 1000 bp appeared at Immediately and two hours post marathon.ConclusionThis study revealed that both serum and urinary cfDNA levels transiently increased after a full marathon. In addition, these cfDNA fragment varied in size.

Background Muscle soreness is also induced during prolonged running such as a full marathon, and muscle soreness and increased damage markers are detected immediately after such a running. We named this muscle soreness, early onset muscle soreness (EOMS). Additionally, lactate dehydrogenase (LDH) level which has some isoenzyme is increased immediately after prolonged exercise. However, it is unclear that EOMS is related to muscle damage markers on prolonged running. This study aimed to determine at which point EOMS, and muscle damage markers are related to EOMS during prolonged running. Methods We studied 11 male subjects who habitually perform aerobic exercise. They ran 30 km at 90% of ventilatory threshold intensity. Every 10 km, we estimated perceived muscle soreness, and sampled blood to measure muscle and liver damage, inflammation, and oxidative stress (d-ROM and BAP) markers. Results Muscle soreness score lower limbs were significantly appeared at 20 km compared to that at 0 km. Serum lactate dehydrogenase (LDH) level increased at 30 km compared to that at 0 km. LDH isoenzymes 3, 4, and 5, and neutrophils significantly increased at 30 km compared to those at 0 km. Serum LDH isoenzyme 5 and change in aspartate aminotransferase significantly increased at 20 km. In addition, there was a significant correlation between the thigh NRS and amount of serum LDH isoenzyme 5 from 0 km to 20 km. d-ROM and BAP increased at 10 km compared to those at 0 km. Conclusions EOMS started to occur at 20 km during a 30 km running task. Our data suggest that LDH isoenzyme 5 is a marker of occurrence in EOMS during prolonged running.

Renalase is a recently discovered flavin adenine dinucleotide (FAD)-dependent soluble monoamine oxidase. It is expressed principally in the kidney, but its expression in the heart, brain, and skeletal muscle has also been confirmed. It is thought that renalase is involved in cardiac function and control of systemic blood pressure primarily by metabolizing circulating catecholamines. Animal experiments have suggested the possibility that exercise is involved in renalase secretion, but this has not been confirmed in human studies. The principal aim of the present study was to investigate the relationship between exercise and renalase concentration in humans. Subjects were young men who were continuously training to run distances of 10-20 km; the total distance that was run in the present study was 30 km. Measurements were performed at four points (before running and after running 10 km, 20 km, and 30 km). The results of one-way analysis of variance examining repeated measurements of serum renalase concentration revealed significant differences (P = 0.007). A significant negative correlation between serum renalase concentration and estimated glomerular filtration rate, which indicates renal function, calculated using serum cystatin C concentration was noted. A significant positive correlation between serum renalase concentration and oxidative stress was observed in the period before exercise and after running 20 km. The present study verified the exercise-induced increase in serum renalase concentration in amateur runners who were continuously training.

Background The aim of the present study was to compare the effects of branched-chain amino acid (BCAA) supplementation taken before or after exercise on delayed onset muscle soreness (DOMS) and exercise-induced muscle damage (EIMD). Methods Fifteen young men (aged 21.5±0.4 years) were given either BCAA (9.6 g·day-1) or placebo before and after exercise (and for 3 days prior to and following the exercise day) in three independent groups: the control group (placebo before and after exercise), the PRE group (BCAA before exercise and placebo after exercise), and the POST group (placebo before exercise and BCAA after exercise). Participants performed 30 repetitions of eccentric exercise with the non-dominant arm. DOMS, upper arm circumference (CIR), elbow range of motion (ROM), serum creatine kinase (CK), lactate dehydrogenase (LDH), and aldolase, BCAA, and β-hydroxy-β-methylbutyrate (3HMB) were measured immediately before and after the exercise and on the following 4 days. Results Serum BCAA and 3HMB concentrations increased significantly in the PRE group immediately after the exercise, recovering to baseline over the following days. In the days following the exercise day, DOMS, CIR, and ROM were significantly improved in the PRE group compared to the control group, with weaker effects in the POST group. Serum activities of CK, LDH, and aldolase in the days following the exercise day were significantly suppressed in the PRE group compared to control group. Conclusions The present study confirmed that repeated BCAA supplementation before exercise had a more beneficial effect in attenuating DOMS and EIMD induced by eccentric exercise than repeated supplementation after exercise.

Taurine is metabolized to a novel metabolite, N-acetyltaurine (NAT), through N-acetylation with acetate. Furthermore, NAT production increases when the endogenous production of acetate is elevated in some situations, such as alcohol catabolism and endurance exercise. We have previously reported that both the serum concentration and urinary excretion of NAT from humans were increased after endurance exercise, and that NAT was secreted by cultured skeletal muscle cells exposed to both acetate and taurine. The present study evaluated the hypothesis that NAT is synthesized in the skeletal muscle after endurance exercise. Normal rats were loaded to a transient treadmill running until exhaustion. Serum, skeletal muscle, and liver were collected immediately after the exercise. The NAT concentration in the plasma and in the soleus muscle from the exercised rats was significantly increased compared to that in the samples from the sedentary control rats. There was a significant positive correlation in the NAT concentration between the plasma and soleus muscle. The NAT concentration in the liver was unchanged after the endurance exercise. These results confirm that the significantly increased NAT in both the serum and urine after endurance exercise is derived from NAT synthesis in the skeletal muscle.

If it were possible to control four sets of PMSMs in place of induction motors by using one inverter, we could attain efficient driving trains. In this paper, a method for controlling three sets of PMSMs with one inverter is shown. Additionally, this shows the method to control four sets of PMSMs with one inverter and the results of a simulation with the proposed method.

An electric power conversion system constructed by connecting two or more electric power converters in parallel is advantageous for achieving large capacity and standardization. In this paper, the control method for cross current when three power converters are operated is examined, and reexamined as a preferable system construction method.

A large-capacity power conversion system constructed by using two or more existing power converters has a lot of flexibility in how the power converters are used. However, at the same time, it has a problem of cross current flows between power converters. The cross current must be suppressed by controlling the system while miniaturizing the combination reactor. This paper focuses on two current control methods of a power conversion system constructed by using two power converters connected in parallel supplying the same power. In order to elucidate the control performance of cross current, each control method which are aimed at controlling cross current and not directly controlling it are examined in simulations.

A new model triathlon suit (NMS) was developed to help the swimming performance of athletes. The NMS is made of highly compressed and highly water-repellent fabric, which is used in competitive swimwear. The aim of this study was to evaluate the NMS by measuring the passive drag and body position during underwater streamline position. The NMS and the old model suit (OMS) were worn by 11 highly competitive varsity swimmers (eight males and three females). The passive drag and body position were measured when both suits were worn in the circulating water channel. The coefficient of passive drag was calculated by the equation. On average, for the whole measurements, there was a reduction in passive drag when wearing the NMS suit of 1.1±5.3% compared with the OMS, whereas there was no statistically significant. The coefficient of the passive drag was not significant difference between both suits. Wearing the NMS showed higher body position compared to the OMS at any velocity, although not significantly. These results suggest that wearing the NMS might help improve swimming performance.

A new optimization system of cycling power was investigated in this paper. The developed system consisted of a newly designed biaxial load cells and analytical system using mechanical model of lower limb. The new biaxial load cells which were made by stainless steel (SUS304) were attached to the bottom of cycling-shoes instead of the plastic cleats. Cyclists are able to connect their cycling-shoes to pedals by the developed load cells. The sizes of load cells were almost same as plastic cleats (Shimano Corp) and measure the magnitude and direction of right and left pedal force using 16-strain gages, respectively. The analytical system solves the link model of human limbs to identify the positions and angles of each segment of lower limbs. The lower limbs model consisted of 3 segments, thigh, shank and foot. All position of every lower limb segments, joint torques and forces were calculated by this system. Additionally, the relationships between ankle angle and crank angle were also modelled by image-analysis software (TEMA 3D) with the high-speed camera (Photron FASTCAM SA4). This cycling power optimization system were applied to the amateur and expert cyclists to investigate applicability of our system.

Taurine is metabolized to a novel metabolite, N-acetyltaurine (NAT), through N-acetylation with acetate. Furthermore, NAT production increases when the endogenous production of acetate is elevated in some situations, such as alcohol catabolism and endurance exercise. We have previously reported that both the serum concentration and urinary excretion of NAT from humans were increased after endurance exercise, and that NAT was secreted by cultured skeletal muscle cells exposed to both acetate and taurine. The present study evaluated the hypothesis that NAT is synthesized in the skeletal muscle after endurance exercise. Normal rats were loaded to a transient treadmill running until exhaustion. Serum, skeletal muscle, and liver were collected immediately after the exercise. The NAT concentration in the plasma and in the soleus muscle from the exercised rats was significantly increased compared to that in the samples from the sedentary control rats. There was a significant positive correlation in the NAT concentration between the plasma and soleus muscle. The NAT concentration in the liver was unchanged after the endurance exercise. These results confirm that the significantly increased NAT in both the serum and urine after endurance exercise is derived from NAT synthesis in the skeletal muscle.

If it were possible to control four sets of permanent magnet synchronous motor (PMSMs) in place of induction motors by using one inverter, we would be able to manufacture efficiently running trains. Therefore, we previously proposed a method for controlling two or more sets of PMSMs with one inverter. For this study, we conducted a parameter survey on the load changes through simulation and a mini model experiment by using a model in which a driving system was simplified into two motors.

Parallel operation systems constructed quickly and inexpensively by combining two or more existing electric power converters have a lot of flexibility. However, it is important to suppress a cross current flows between the electric power converters. This paper proposes a three inputs combination reactor for parallel operation systems composed three electric power converters.

Large-capacity parallel operation systems constructed quickly and inexpensively by combining two or more existing electric power converters have a lot of flexibility. However, it is important to suppress the cross current flows between the converters. This can be done by controlling the system while miniaturizing the combination reactor. In this paper we elucidate the suppression performance of various cross current control methods and provide design guidelines for them.

The oxidative cyclization–carbonylation of propargylic esters mediated by Pd(II) afforded cyclic orthoesters, which were hydrolyzed into γ-acetoxy-β-ketoesters. Based on the NMR experiments, it was presumed that the cyclization reaction was initiated by a nucleophilic attack of carbonyl oxygen to the alkyne carbon coordinated to palladium(II). When the γ-acetoxy-β-ketoesters were treated with a basic condition, Knoevenagel–Claisen type condensation took place, and spiro furanone derivatives were obtained in good yields. We applied these reactions to steroid derivatives, and steroid derivatives having a spiro furanone fragment were synthesized. Among them, the spiro furanone 4j had vasorelaxant and bradycardiac activities. Compounds 2i–4k had inhibitory effect on CYP3A.

N-acetyltaurine (NAT) that is a novel metabolite of taurine conjugated with acetate has been reported to increase in urine during alcohol catabolism. Because acetate production would be also increased by endurance exercise, NAT might be produced during the exercise. This study aimed to determine the NAT in serum and urine after endurance exercises. Serum and urinary levels of taurine and NAT after a transient exercise or full-marathon race were measured by HPLC-MS/MS system. In addition, the synthesis of NAT was evaluated in cultured skeletal muscle cell (C2C12 myotube) exposed to taurine and acetate. Serum taurine and NAT concentrations were significantly increased immediately after full-marathon compared to those before the marathon, and recovered to the normal levels after a day. Urinary excretions of taurine and NAT were markedly higher in 24-h period after the transient exercise compared to those before the exercise. In culture cell, the excretion of NAT to medium was significantly increased following the exposing to both taurine and acetate. The present study could confirm the significant increase of NAT in serum and urine after endurance exercise, and it is suggesting that taurine may conjugate with excess acetyl-group in the skeletal muscles during exercise.

A large-capacity power conversion system for a permanent magnet (PM) motor drive consisting of two or more converters has a lot of flexibility. However, it is important to suppress cross current between the two converters. This paper investigates the cross current suppression performance of each control method and provides useful hints about the current control loop gain setting and reactance of the combination reactor.

If two or more Permanent Magnet Synchronous Motors (PMSM) can be controlled by one inverter, a train can be driven by less energy than the present Induction Motor (IM) drive system. First, this paper proposes a method for simulating the movement of wheels and a vehicle to develop a control method. Next, a method is presented for controlling two or more PMSMs by one inverter.

Taurine (TAU) has a lot of the biological, physiological, and pharmocological functions including anti-inflammatory and anti-oxidative stress. Although previous studies have appreciated the effectiveness of branched-chain amino acids (BCAA) on the delayed-onset muscle soreness (DOMS), consistent finding has not still convinced. The aim of this study was to examine the additional effect of TAU with BCAA on the DOMS and muscle damages after eccentric exercise. Thirty-six untrained male volunteers were equally divided into four groups, and ingested a combination with 2.0 g TAU (or placebo) and 3.2 g BCAA (or placebo), thrice a day, 2 weeks prior to and 4 days after elbow flexion eccentric exercise. Following the period after eccentric exercise, the physiological and blood biochemical markers for DOMS and muscle damage showed improvement in the combination of TAU and BCAA supplementation rather than in the single or placebo supplementations. In conclusion, additional supplement of TAU with BCAA would be a useful way to attenuate DOMS and muscle damages induced by high-intensity exercise.

A visualization system for cycling pedaling technique is investigated in this paper. This system consists of the visualization of pedaling effectiveness and pedaling force vectors. Pedaling effectiveness is defined as the ratio of the tangential to total force applied to the pedals. New biaxial load cells were also developed to attach to the bottom of cycling shoes in place of plastic cleats. These load cells can be connected to the bicycle pedals to measure the magnitude and direction of pedaling forces of both pedals, respectively. The size of load cells is comparable with detachable plastic cleats (Shimano Corp). Therefore, cyclists were permitted to use their own bicycles for performance tests. For visualization of pedaling effectiveness, each force measured by the load cell was converted to coordinates respective to the tangential and radial directions of each crank. The crank angle was calculated from the signal of a magnetic transducer. The pedal angle was calculated using a link mechanism with the lower limbs: the length of the lower limbs, the length of the crank and the position of the greater trochanter were used as constant parameters for computational calculations. For visualization, the relationship between crank angle and force vectors was plotted on a computer, just after the performance tests. This information would be provided for coaches and cyclists in order to identify improvement points for pedaling technique.

Background Previous studies have evaluated the effectiveness of branched-chain amino acid (BCAA) supplementation for preventing delayed onset muscle soreness (DOMS) and muscle damage induced by eccentric exercise, their findings have been inconclusive. Since taurine has anti-inflammatory and anti-oxidative effects, the present study investigated the combined effect of BCAA and taurine on DOMS and muscle damage. Methods Thirty-six untrained male subjects (22.5 ± 3.8 years) were assigned to four groups (placebo + placebo [placebo], BCAA + placebo, placebo + taurine, and BCAA + taurine [combined]) and given a combination of 3.2 g BCAA (or placebo) and 2.0 g taurine (or placebo), three times a day, for two weeks prior to and three days after eccentric elbow flexor exercises. DOMS and muscle damage in the biceps brachii were subjectively and objectively evaluated using the visual analogue scale (VAS), upper arm circumference (CIR), and blood parameters (creatine kinase, lactate dehydrogenase [LDH], aldolase, and 8-hydroxydeoxyguanosine [8-OHdG]). Results In the combined group, VAS and 8-OHdG two days after exercise, CIR two and three days after exercise and LDH from one to three days after exercise were significantly lower than the placebo group. The area under the curve from before exercise to four days later for CIR, LDH, and aldolase was also significantly lower in the combined group than in the placebo group. Conclusion A combination of 3.2 g BCAA and 2.0 g taurine, three times a day, for two weeks prior to and three days after exercise may be a useful nutritional strategy for attenuating exercise-induced DOMS and muscle damage.