Ryotaro Kime

• Tokyo Medical University

The aim of this study was to investigate the skeletal muscle O2 dynamics during body-weight resistance exercise with slow movement and tonic force generation. Thirteen untrained, healthy, young males performed Bulgarian split squats and push-ups until volitional failure. Relative changes from rest in oxygenated haemoglobin (oxy-Hb) and deoxygenated...

Near-infrared spectroscopy (NIRS) has been used to measure skeletal muscle oxidative function for more than 30 years. Several indicators evaluate muscle oxidative function using NIRS during exercise, such as deoxygenation rate at the start of exercise (Deoxy-rate), changes in deoxygenation during exercise (ΔDeoxy), and reoxygenation speed after exe...

Nattokinase (NK) intake may improve blood flow; however, its effects on skin temperature, which is predominantly controlled by skin surface blood flow, are unknown. The purpose of this study was to determine the effects of a single dose of NK on changes in skin temperature after cold water immersion. A double-blinded, placebo-controlled, crossover...

The aim of this study was to compare systemic and quadriceps muscle O2 dynamics between aerobic capacity-matched subjects without (NAP; n = 5) and with (CON; n = 13) attenuation point in deoxygenated haemoglobin concentration (deoxy-Hb) at vastus lateralis (APdeoxy-Hb@VL) during ramp cycling exercise. Muscle O2 saturation (SmO2) and deoxy-Hb were m...

There is no evidence of the effect of exercise training on human brown-like adipose tissue vascular density (BAT-d). Here, we report whether whole-body strength training (ST) in a cold environment increased BAT-d. The participants were 18 men aged 20–31 years. They were randomly assigned to two groups: one that performed ST twice a week at 75% inte...

Background and objective The importance of brown adipose tissue (BAT) is well recognized in healthy infants and children. However, information regarding age-related changes in BAT vascular density (BAT-d) and the impact of BAT-d on body adiposity are lacking. This study aimed to evaluate the normal values of BAT-d, factors influencing BAT-d, and th...

This study examined the relationship between plasma amino acid (AA) concentrations, including branched-chain AAs, and brown adipose tissue density (BAT-d). One hundred and seventy-three subjects (69 men, 104 women) aged 22–68 years were recruited during the winter season. AAs were comprehensively quantified using liquid chromatography-time-of-fligh...

The aim of this study was to compare muscle O2 dynamics during exercise among elderly (n = 10, age: 73 ± 3 years), middle-aged (n = 9, age: 50 ± 6 years), and young (n = 10, age: 25 ± 3 years) adults. The subjects performed ramp bicycle exercise until exhaustion. Muscle O2 saturation (SmO2) and relative changes from rest in oxygenated hemoglobin/my...

The primary symptom in patients with chronic heart failure (CHF) is exercise intolerance. Previous studies have reported that reduced exercise tolerance in CHF can be explained not only by cardiac output (a central factor) but also by reduced skeletal muscle aerobic capacity (a peripheral factor). Although exercise training in CHF improves exercise...

Previous studies have reported that the reduced scattering coefficient (μs′) in the vastus lateralis changes during ramp-incremental exercise due to blood volume changes or accumulation of metabolic by-products. We aimed to clarify the influences of deoxygenation and blood volume changes during exercise on μs′ dynamics in subjects with various aero...

Purpose: Near-infrared spectroscopy (NIRS), performed with a commonly available noninvasive tissue oxygenation monitoring device, is based on the modified Beer-Lambert law (MBLL). Although NIRS based on MBLL (NIRSMBLL) assumes that the optical path length (PL) is constant, the effects of changes in PL during exercise on muscle oxygenation calculate...

Capsinoids are some of the most promising ingredients to increase energy expenditure (EE) due to brown adipose tissue (BAT) activation. However, there is limited information regarding the effect of prolonged capsinoid ingestion (CI) on BAT activity and resting EE (REE) in healthy, middle-aged, normal to overweight subjects (Subhealthy) with distinc...

The thermogenic function of brown adipose tissue (BAT) is generally activated in winter and tightly regulated through various metabolic processes. However, the mechanisms mediating these changes have not been elucidated in humans. Here, we investigated the relationships between BAT density (BAT-d) and lipid metabolites in plasma from men and women...

Brown adipose tissue (BAT) mediates adaptive thermogenesis upon food intake and cold exposure, thus potentially contributing to the prevention of lifestyle-related diseases. 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) with computed tomography (CT) (18FDG-PET/CT) is a standard method for assessing BAT activity and volume in human...

Brown adipose tissue (BAT) plays a role in adaptive thermogenesis in response to cold environments and dietary intake via sympathetic nervous system (SNS) activation. It is unclear whether physical activity increases BAT density (BAT-d). Two-hundred ninety-eight participants (age: 41.2 ± 12.1 (mean ± standard deviation), height: 163.6 ± 8.3 cm, wei...

Near-infrared time-resolved spectroscopy (NIRTRS) can quantitatively evaluate mean optical path length (MPL). Since an increase in optical absorbers in the NIR region (e.g. an increase in deoxygenated hemoglobin during exercise) would shorten the MPL, the NIRS measurement area may vary depending on physical and physiological characteristics of the...

The aim of this study was to compare muscle O2 dynamics during exercise between aerobic capacity-matched overweight and normal-weight adults. Overweight women (OW, n = 9) and normal-weight women (NW, n = 14) performed graded treadmill exercise until exhaustion. Muscle O2 saturation (SmO2) and relative changes from rest in deoxygenated hemoglobin co...

High whole-body and visceral adiposity are risk factors that can cause metabolic diseases. We hypothesized that the total hemoglobin concentration (total-Hb) in abdominal subcutaneous adipose tissue (SATab), an indicator of white adipose tissue (WAT) vascularity, correlates negatively with risk factors for developing metabolic diseases, such as who...

Brown adipose tissue (BAT) may potentially be used in strategies for preventing lifestyle-related diseases. We examine evidence that near-infrared time-resolved spectroscopy (NIRTRS) is capable of estimating human BAT density (BAT-d). The parameters examined in this study are total hemoglobin [total-Hb]sup, oxygenated Hb [oxy-Hb]sup, deoxygenated H...

This study quantitatively analyzed the effects of 3 h of constant sitting on skeletal muscle oxygenation in the lower extremities, using near-infrared time-resolved spectroscopy (NIRTRS). The effects of compression stockings were also evaluated. Eleven healthy men (age, 30.0 ± 6.7 years) maintained their knee joints at 90° flexion during 3 h of con...

Objective Our aim was to determine the effects of a single-dose of nattokinase administration on activity of natural killer (NK) cells, blood pressure, and body temperature in healthy male Japanese. Methods A randomized, double-blind, placebo-controlled crossover nattokinase intervention study was carried out in 10 healthy males (30.2±7.6 yr). Foll...

Fat layer thickness (FLT) affects near infrared spectroscopy (NIRS) measurement. The aim of this study was to determine an indicator of muscle function with less influence of FLT, even without normalization, by comparing muscle O2 dynamics during exercise in subjects with similar physical characteristics except for FLT. Healthy male subjects with t...

The aim of this study was to test the effects of aerobic cycling training on O2 dynamics in several leg muscles in early post-myocardial infarction (post-MI). Fifteen post-MI patients were divided into a 12-week training group (TR, n = 9) or a control/non-training group (CON, n = 6). All participants performed ramp bicycle exercise until exhaustion...

F18-fluorodeoxyglucose (FDG)-positron emission tomography (PET) along with computed tomography (CT) is a standard method for assessing brown adipose tissue (BAT) activity. We tested the usefulness of near-infrared time-resolved spectroscopy (NIRTRS) as a simple and noninvasive method for evaluating BAT density (BAT-d) by examining the effects of so...

Background: Near-infrared time-resolved spectroscopy is a non-invasive method that facilitates analysis of human brown adipose tissue (BAT) density. We measured BAT density in middle-aged patients who had type 2 diabetes by this method and examined the relationship using clinical parameters. Methods: We studied 33 Japanese middle-aged diabetic pati...

The aim of this study was to compare the muscle oxygen dynamics between early post-myocardial infarction (n = 12; MI) and age-matched elderly subjects without MI (n = 12; CON) in several leg muscles during ramp cycling exercise. Muscle oxygen saturation (SmO2), deoxygenated-hemoglobin concentration (∆deoxy-Hb), and total-hemoglobin concentration (∆...

The aim of this study was to investigate the effects of 8 weeks of training on O2 dynamics in university rugby players. University rugby players (n = 15) participated in 5 strength training sessions and 4 field-based training sessions per week for 8 weeks. Before and after 8-weeks’ training, the subjects performed ramp cycling exercise until exhaus...

The purpose of this study was to elucidate the time course of muscle deoxygenation and its heterogeneity changes through endurance training. Nine healthy untrained male participated in this study. The subjects performed a ramp incremental cycle exercise protocol to estimate VO2peak and muscle tissue oxygen saturation (SmO2) distribution in the VL m...

Muscle O2 dynamics during ramp cycling exercise were compared between angina pectoris patients (AP; n = 7, age: 73 ± 6 years) after coronary artery bypass grafting and age-, height-, and body weight-matched elderly control subjects (CON; n = 7, age: 74 ± 8 years). Muscle O2 saturation (SmO2) and relative change in deoxygenated (∆deoxy-Hb) and total...

The aim of this study was to investigate the effect of low volume aerobic exercise training on muscle O2 dynamics during exercise in early post-angina pectoris (AP) patients, as a pilot study. Seven AP patients (age: 72 ± 6 years) participated in aerobic exercise training for 12 weeks. Training consisted of continuous cycling exercise for 30 min at...

Purpose: Exercise-induced skeletal muscle deoxygenation is startling by its absence in early post-myocardial infarction (MI) patients. Exercise training early post-MI is associated with reduced cardiovascular risk and increased aerobic capacity. We therefore investigated whether aerobic training could enhance the muscle deoxygenation in early post...

Aging enhances muscle desaturation responses due to reduced O2 supply. Even though aerobic training enhances muscle desaturation responses in young subjects, it is unclear whether the same is true in elderly subjects. Ten elderly women (age: 62 ± 4 years) participated in 12-weeks of cycling exercise training. Training consisted of 30 min cycling ex...

The aim of this study was to detect the differences in muscle metabolic response of the quadriceps during incremental dynamic knee exercise using regional 31Phosphorus Chemical Shift Imaging (31P-CSI). Sixteen healthy men participated in this study (age 28 ± 5 years, height 171.4 ± 3.9 cm, weight 67.1 ± 9.8 kg). The experiments were carried out wit...

Muscle tissue oxygenation is a critical issue in muscle complications such as pain, exhaustion, stiffness, or fatigue during and after exercise. The aim of this study was to investigate whether the changes of muscle tissue oxygenation could be observed at both erector spinae muscle at S1 level and gastrocnemius during and after acupuncture stimulat...

An increase in the incidence rate of cardiovascular disease is attributed to high daily sitting time, while a drop in risk of cardiovascular disease comes from a decrease in daily sitting time, rather than an increase in physical activity levels. Although short-duration passive exercise increases energy expenditure and blood flow, few studies have...

Muscle O2 dynamics during ramp cycling exercise were compared between aerobic capacity-matched elderly men (n = 8, age 65 ± 2 years) and women (n = 8, age 66 ± 3 years). Muscle O2 saturation (SmO2) and relative change in deoxygenated (Δdeoxy-Hb) and total hemoglobin concentration (Δtotal-Hb) were monitored continuously during exercise in the vastus...

Previous studies have reported significant region-dependent differences in the fiber-type composition of human skeletal muscle. It is therefore hypothesized that there is a difference between the deep and superficial parts of muscle energy metabolism during exercise. We hypothesized that the inorganic phosphate (Pi)/ phosphocreatine (PCr) ratio of...

Aim: Comprehensive arterial blood flow (BF) in the abdominal-pelvic viscera (BFVis) can be calculated by subtracting right and left femoral arterial BF (BFRFA and BFLFA, respectively) from upper abdominal aorta BF (BFAo) above the coeliac trunk. The aim of the present study was to evaluate the time course in BFVis and its relation to hemodynamic pa...

Purpose Muscle unloading causes muscle function deterioration, but the extent to which training frequency or volume can be reduced while preserving muscle function during muscle unloading is unknown. We examined the effects of low-volume muscle endurance and strength training on forearm muscle oxidative capacity, endurance, and strength during a 3...

Exercising muscle blood flow (BF) may be an indicator of oxygen supply change allowing increased muscle energy metabolism through the circulatory response between central and peripheral hemodynamics. During exercise an increase in cardiac output may represent the interplay of alterations in both blood pressure and vascular conductance. Dynamic musc...

Muscle O2 saturation (SmO2) and blood volume response in activating muscles during treadmill exercise were compared between prepubertal boys (n = 9, age: 9 ± 1 years) and young men (n = 9, age: 22 ± 2 years). SmO2 and blood volume responses were monitored continuously during the exercise at the gastrocnemius medialis muscle by near infrared spatial...

Reduced peak aerobic capacity in chronic heart failure can be partly explained by impaired peripheral factors. However, skeletal muscle deoxygenation responses during exercise and their relationship to peak aerobic capacity have not been fully established in early post-myocardial infarction (MI) patients. Patients early post-MI (age 61 ± 9, n=16, 2...

To examine the hypothesis that the relationship between minute ventilation (VE) and deoxygenation from the intercostal space (IC) would be steady regardless of exercise protocols, if an increase in O2 consumption of the accessory respiratory muscles with an increase of VE brings about deoxygenation in IC, we measured the relationship between VE and...

We compared muscle oxygen saturation (SmO2) responses in several leg muscles and within a single muscle during ramp cycling exercise between elderly men (n = 8; age, 65 ± 3 years; ELD) and young men (n = 10; age, 23 ± 3 years; YNG). SmO2 was monitored at the distal site of the vastus lateralis (VLd), proximal site of the vastus lateralis (VLp), rec...

Recently, deoxygenated hemoglobin (HHb) has been used as one of the most popular indicators of muscle O2 extraction during exercise in the field of exercise physiology. However, HHb may not sufficiently represent muscle O2 extraction, as total hemoglobin (tHb) is not stable during exercise. The purpose of this study was to measure various muscle ox...

The purpose of this study was to examine the relationship between muscle oxygenation kinetics and tolerance to fatigue (Fr) on short-term maximal isometric knee extension exercise for healthy endurance-trained women. The decline rate of Tissue Oxygenation Index (TOI) at the onset of exercise had a significant negative correlation to Fr (r=-0.76, p<...

We examined whether O(2) saturation in several leg muscles changes as exercise intensity increases. Twelve healthy young males performed 20 W/min ramp bicycle exercise until exhaustion. Pulmonary O(2) uptake (VO(2)) was monitored continuously during the experiments to determine peak oxygen uptake. Muscle O(2) saturation (SmO(2)) was also monitored...

Pulmonary O2 uptake (VO2) increases almost linearly during incremental cycling exercise, whereas deoxygenation of the vastus lateralis muscle (VL), measured by near-infrared spectroscopy, develops continuously and then attenuates before reaching VO2 peak (VO2peak). The mechanisms behind these are unclear. In previous studies, it was speculated that...

The aim of this study was to investigate the relationship between the attenuation point of muscle deoxygenation (APMD) and the EMG threshold (EMGT) during incremental cycling exercise under different fractions of inspired O2 (FIO2). Nine male subjects performed ramp cycling exercise tests (20 W·min(-1)) to exhaustion under normoxic and hypoxic cond...

We present a method for simultaneous measurement of optical absorption coefficients for skin (μas) and muscle (μam) tissues using spatially resolved near-infrared spectroscopy (SRS). A novel calculation algorithm was developed to determine the absorption coefficients of superficial and deep layers within a three-layered structure using Monte Carlo...

Arterial blood flow (BF) to all abdominal-pelvic organs (AP) shows potential for an indicator of comprehensive splanchnic organ circulation (reservoir of blood supply for redistribution) in cardiovascular disease, hepato-gastrointestinal disease or hemodynamic disorders. Our previous assessment of splanchnic hemodynamics, as magnitude of BFAP [meas...

We examined the relationship between the time constant (Tc) for muscle oxygen consumption (VO 2mus) recovery after exercise, as measured by near-infrared continuous wave spectroscopy (NIRcws), and the Tc for phosphocreatine (PCr) recovery as an index of muscle oxidative capacity. Eight healthy male subjects performed a dynamic handgrip exercise, an...

We examined the effect of 3-week upper limb immobilization on conduit artery cross-sectional area and peak hyperemia (BF(peak)) after exhaustive dynamic handgrip exercise (Ex(dyn)), and that of low-volume strength and endurance training during immobilization. Healthy volunteers (n = 21; mean age, 22 years) were divided into 3 groups: immobilization...

This study investigated heterogeneity of muscle O(2) consumption (diffusive m-VO(2)) and muscle oxygenation difference (m-O(2) difference) within the forearm flexor muscles using multi-optical fibers near-infrared continuous wave spectroscopy (NIRcws) during incremental exercise. Nine healthy male subjects performed incremental dynamic handgrip exe...

The purpose of this study was to investigate the effects of acute hypoxia on the inflection point of muscle oxygenation (IPMO) using near-infrared spectroscopy during incremental bicycle exercise. Eight male subjects (age: 22 +/- 2 years) performed two ramp incremental bicycle exercise tests until exhaustion under each normoxic and hypoxic (F(I)O(2...

The purpose of this study was to examine the changes in muscle oxygen saturation (SmO(2)) level and its heterogeneity after 6 weeks of endurance training using multi-channel near infrared spatially resolved spectroscopy (NIR(SRS)). Nine healthy subjects participated in this study (Male = 6, Female = 3, age: 27 +/- 5 years, height: 168.7 +/- 7.4 cm,...

We evaluated arterial blood flow, muscle tissue oxygenation and muscle metabolism in the non-exercising limb during leg cycling exercise. Ten healthy male volunteers performed a graded leg cycling exercise at 0, 40, 80, 120 and 160 watts (W) for 5 min each. Tissue oxygenation index (TOI) of the non-exercising left forearm muscle was measured using...

We have developed an exercise machine prototype for increasing exercise intensity by means of passively exercising lower limb muscles. The purpose of the present study was to compare the passive exercise intensity of our newly-developed machine with the intensities of different types of exercises. We also attempted to measure muscle activity to stu...

The authors have developed a new "Passive Exercise Technology and Equipment" which can induce muscular contraction of the functional muscles around knee joint. Users, who would not like to exercise but also contract with both type 2 diabetes and/or knee joint osteoarthritis, can perform exercise just by following the equipment's motion while sittin...

Arterial blood flow (BF) to all abdominal-pelvic organs (AP) is a potentially useful indicator of splanchnic circulatory dysfunction or various stress-induced AP flow distributions. BFAP can be measured by subtracting BF in the "peripheral" bilateral limb left/right-femoral arteries (FA) from the "central" upper abdominal aorta (Ao) above the celia...

The purpose of this study was to examine the changes in total hemoglobin (Delta[tHb]) response during bicycle exercise at various constant workloads using near infrared continuous wave spectroscopy (NIRcws) in humans. We hypothesized that the Delta[tHb] during exercise may progressively increase as a result of a dilation of the vascular bed and/or...

This study aimed to compare the trapezius muscle blood volume and oxygenation in the stimulation region and in a distant region in the same muscle during acupuncture stimulation (AS). We hypothesized that AS provokes a localized increase in muscle blood volume and oxygenation in the stimulation region. Two sets of near-infrared spectrometer (NIRS)...

The purpose of this study was to determine whether endurance and strength hand grip exercises during 3-week upper limb immobilization preserve muscle oxidative capacity, endurance performance and strength. Ten healthy adult men underwent non-dominant forearm immobilization by plaster cast for 21 days. Five healthy adult subjects were designated as...

The pulsed Doppler method theoretically enables human arterial blood flow (BF) to be determined in all of the abdominal-pelvic organs (BF(AP)) by subtracting the bilateral proximal femoral arterial BF from the upper abdominal aorta BF above the coeliac trunk. Evaluation of BF(AP) is a potentially useful indicator of exercise or food intake related...

The purpose of this study was to examine the effect of low- vs. high-intensity resistance exercise on lipid peroxidation. In addition, the role of muscle oxygenation on plasma malondialdehyde (MDA) concentrations was explored. Eleven experienced resistance trained male athletes (age: 20.8 +/- 1.3 years; weight: 96.2 +/- 14.4 kg; height: 182.4 +/- 7...

We evaluated regional differences of muscle O 2 dynamics between distal and proximal sites in the vastus lateralis (VL) muscle using near infrared spatial resolved spectroscopy (NIR SRS). forty-one male subjects performed a 30 W ramp incremental bicycle exercise test until exhaustion. The NIR SRS probes were attached on each distal and proximal sit...

The purpose of this study was to determine the age and habitual physical activity on re-oxygenation time in working muscles following maximal cycling exercise (CycEXmax). Twelve sedentary middle-aged (50±6), 13 sedentary elderly (66±3), 13 active middle-aged (53±5), and 20 active elderly (67±5) were evaluated the half re-oxygenation time (T1/2 reox...

The purpose of this study was to clarify the effects of bicycle ergometer training and prostaglandin E1 (PGE1) for patients with intermittent claudication. Subjects were divided into four groups: the medication group (M), the PGE1 group (P), the exercise group (E) and the PGE1 and exercise group (PE). The P group was injected with 10 μg of PGE1, th...

The purpose of this study was to determine the interaction of age and habitual physical activity on recovery time of muscle oxygenation following maximal cycling exercise (CycEXmax). Twelve sedentary middle-aged (50+/-6), 13 sedentary elderly (66+/-3), 13 active middle-aged (53+/-5), and 20 active elderly (67+/-5) women participated in this study....

This article introduces a novel method to continuously monitor regional muscle blood flow by using Near Infrared Spectroscopy (NIRS). We demonstrate the feasibility of the new method in two ways: (1) by applying this new method of determining blood flow to experimental NIRS data during exercise and ischemia; and, (2) by simulating muscle oxygenatio...

Ten intercollegiate football players were tested within 3 days prior to (T1) and the day following the end (T2) of football preseason training camp and during weeks 7 (T3) and 11 (T4) of the competitive season. During each testing session, subjects performed a 30-second Wingate anaerobic power test. Near-infrared continuous wave spectroscopy was us...

The frequency-domain near-infrared spectrometry (NIRS) is capable of measuring the absolute absorption and reduced scattering coefficient of tissue noninvasively. This allows the quantitation of tissue hemoglobin concentration which reflects the balance between oxygen delivery and oxygen utilization of the skeletal muscle. Phosphorus magnetic reson...

Purpose: The mechanisms that underlie the affect of acute program variables on muscle growth and strength development for strength/power athletes have been of great interest. This investigation examined the affects of two different resistance exercise protocols on muscle oxygenation, and the anabolic hormonal response to such exercise. Methods: Ele...

This study evaluated heterogeneity of muscle O2 dynamics in a single muscle during bicycle exercise using an eight-channel near-infrared continuous wave spectroscopy (NIRcws) mapping system. Nine healthy subjects performed bicycle exercise at fixed workloads of 20, 40, 60, 80, and 100% maximal workload for 5 min at each level. Muscle oxygenation in...

Background It has been thought that intramuscular ADP and phosphocreatine (PCr) concentrations are important regulators of mitochondorial respiration. There is a threshold work rate or metabolic rate for cellular acidosis, and the decrease in muscle PCr is accelerated with drop in pH during incremental exercise. We tested the hypothesis that increa...

A new prototype apparatus for passive exercise training has been developed which is based on the concept that exercise could be induced by external stimulation without the patient's voluntary effort and even patients with knee joint pain easily perform exercise while sitting on this equipment. Evaluation of the effect on knee joint by biomechanics...

Post-exercise related time course of muscle oxygenation during recovery provides valuable information on peripheral vascular disease. The purpose of the present study was to examine post-exercise hyperemia (forearm blood flow; FBF, Doppler ultrasound) assessed by peak FBF, excess FBF and the time constant for FBF (FBF(Tc)) following isometric handg...

The approach of site-specific watershed management to achieve water quality goals is discussed. The approach was initiated by The U.S. Environmental Protection Agency (EPA) with the 1994 National Pollutant Discharge Elimination System (NPDES) watershed strategy. Various water quality problems at different water shed locations such as Neuse river, S...