Kobe, Japan

Kobe Design University is a private university in Kobe, Hyōgo, Japan.It was established in 1989 by Tanioka Gakuen Educational Foundation , which runs several schools such as Osaka University of Commerce. Wikipedia.

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Koga S.,Kobe Design University | Poole D.C.,Kansas State University | Kondo N.,Kobe University | Oue A.,Toyo University | And 2 more authors.
European Journal of Applied Physiology | Year: 2014

Purpose: We quantified the contribution of skin blood flow (SkBF) to tissue oxygenation/deoxygenation of the flexor digitorum profundus muscle during cutaneous vasodilation.Methods: Time-resolved near-infrared spectroscopy (TRS-NIRS) was utilized to measure the potential influence of optical factors [mean optical pathlength (PL) and coefficients of absorption (μa) and reduced scattering ((Formula presented.))] on the NIRS-derived signals of eight male subjects.Results: The approximately threefold elevation of SkBF during 1 h whole-body heating (increased internal temperature ~0.9 °C) increased both μa and (Formula presented.) without changing PL. Assuming that the (Formula presented.) coefficient remained constant, i.e., as with continuous-wave (CW) NIRS, resulted in a significant increase in the apparent oxygenation [oxy(Hb + Mb), from 113 ± 13 μM (mean ± SD) for control to 126 ± 13 for the increased SkBF condition, P < 0.01]: this was in marked contrast to the unchanged TRS-derived values. The deoxygenation [deoxy(Hb + Mb)] also increased from control to elevated SkBF (CW-NIRS, from 39 ± 8 to 45 ± 7; TRS, from 38 ± 6 to 44 ± 7 μM; P < 0.01 for both), but less than that seen for oxy(Hb + Mb) and not different between TRS- and CW-NIRS. Further, and in contrast to oxy(Hb + Mb), temporal profiles of deoxy(Hb + Mb) measured by the two NIRS methods were not different.Conclusions: These findings support use of either NIRS method to estimate local muscle fractional O2 extraction, but not oxygenation, when SkBF is increased at rest. © 2014, Springer-Verlag Berlin Heidelberg.

Koga S.,Kobe Design University | Kano Y.,University of Electro - Communications | Barstow T.J.,Kansas State University | Ferreira L.F.,University of Florida | And 3 more authors.
Journal of Applied Physiology | Year: 2012

The overarching presumption with near-infrared spectroscopy measurement of muscle deoxygenation is that the signal reflects predominantly the intramuscular microcirculatory compartment rather than intramyocyte myoglobin (Mb). To test this hypothesis, we compared the kinetics profile of muscle deoxygenation using visible light spectroscopy (suitable for the superficial fiber layers) with that for microvascular O 2 partial pressure (i.e., Pmv O2, phosphorescence quenching) within the same muscle region (0.5̃1 mm depth) during transitions from rest to electrically stimulated contractions in the gastrocnemius of male Wistar rats (n = 14). Both responses could be modeled by a time delay (TD), followed by a close-to-exponential change to the new steady level. However, the TD for the muscle deoxygenation profile was significantly longer compared with that for the phosphorescencequenching Pmv O2 [8.6 ± 1.4 and 2.7 ± 0.6 s (means ± SE) for the deoxygenation and Pmv O2, respectively; P < 0.05]. The time constants (τ) of the responses were not different (8.8 ± 4.7 and 11.2 ± 1.8 s for the deoxygenation and Pmv O2, respectively). These disparate (TD) responses suggest that the deoxygenation characteristics of Mb extend the TD, thereby increasing the duration (number of contractions) before the onset of muscle deoxygenation. However, this effect was insufficient to increase the mean response time. Somewhat differently, the muscle deoxygenation response measured using nearinfrared spectroscopy in the deeper regions (̃5 mm depth) (̃50% type I Mb-rich, highly oxidative fibers) was slower (τ = 42.3 ± 6.6 s; P < 0.05) than the corresponding value for superficial muscle measured using visible light spectroscopy or Pmv O2 and can be explained on the basis of known fiber-type differences in Pmv O2 kinetics. These data suggest that, within the superficial and also deeper muscle regions, the τ of the deoxygenation signal may represent a useful index of local O 2 extraction kinetics during exercise transients. Copyright © 2012 the American Physiological Society.

Koga S.,Kobe Design University | Poole D.C.,Kansas State University | Fukuoka Y.,Doshisha University | Ferreira L.F.,University of Florida | And 3 more authors.
American Journal of Physiology - Regulatory Integrative and Comparative Physiology | Year: 2011

The conventional continuous wave near-infrared spectroscopy (CW-NIRS) has enabled identification of regional differences in muscle deoxygenation following onset of exercise. However, assumptions of constant optical factors (e.g., path length) used to convert the relative changes in CW-NIRS signal intensity to values of relative concentration, bring the validity of such measurements into question. Furthermore, to justify comparisons among sites and subjects, it is essential to correct the amplitude of deoxygenated hemoglobin plus myoglobin [deoxy(Hb+Mb)] for the adipose tissue thickness (ATT). We used two time-resolved NIRS systems to measure the distribution of the optical factors directly, thereby enabling the determination of the absolute concentrations of deoxy(Hb+Mb) simultaneously at the distal and proximal sites within the vastus lateralis (VL) and the rectus femoris muscles. Eight subjects performed cycle exercise transitions from unloaded to heavy work rates (>gas exchange threshold). Following exercise onset, the ATT-corrected amplitudes (Ap), time delay (TDp), and time constant (τp) of the primary component kinetics in muscle deoxy(Hb+Mb) were spatially heterogeneous (intersite coefficient of variation range for the subjects: 10-50 for Ap, 16-58 for TDp, 14-108% for τp). The absolute and relative amplitudes of the deoxy(Hb+Mb) responses were highly dependent on ATT, both within subjects and between measurement sites. The present results suggest that regional heterogeneity in the magnitude and temporal profile of muscle deoxygenation is a consequence of differential matching of O2 delivery and O2 utilization, not an artifact caused by changes in optical properties of the tissue during exercise or variability in the overlying adipose tissue. © 2011 the American Physiological Society.

Koga S.,Kobe Design University | Rossiter H.B.,University of Leeds | Heinonen I.,University of Turku | Heinonen I.,Erasmus Medical Center | And 2 more authors.
Medicine and Science in Sports and Exercise | Year: 2014

Resolving the bases for different physiological functioning or exercise performance within a population is dependent on our understanding of control mechanisms. For example, when most young healthy individuals run or cycle at moderate intensities, oxygen uptake (V̇O2) kinetics are rapid and the amplitude of the V̇O2 response is not constrained by O 2 delivery. For this to occur, muscle O2 delivery (i.e., blood flow × arterial O2 concentration) must be coordinated superbly with muscle O2 requirements (V̇O2), the efficacy of which may differ among muscles and distinct fiber types. When the O2 transport system succumbs to the predations of aging or disease (emphysema, heart failure, and type 2 diabetes), muscle O2 delivery and O2 delivery-V̇O2 matching and, therefore, muscle contractile function become impaired. This forces greater influence of the upstream O2 transport pathway on muscle aerobic energy production, and the O2 delivery-V̇O2 relationship(s) assumes increased importance. This review is the first of its kind to bring a broad range of available techniques, mostly state of the art, including computer modeling, radiolabeled microspheres, positron emission tomography, magnetic resonance imaging, near-infrared spectroscopy, and phosphorescence quenching to resolve the O2 delivery-V̇O2 relationships and inherent heterogeneities at the whole body, interorgan, muscular, intramuscular, and microvascular/myocyte levels. Emphasis is placed on the following: 1) intact humans and animals as these provide the platform essential for framing and interpreting subsequent investigations, 2) contemporary findings using novel technological approaches to elucidate O2 delivery-V̇O 2 heterogeneities in humans, and 3) future directions for investigating how normal physiological responses can be explained by O 2 delivery-V̇O2 heterogeneities and the impact of aging/disease on these processes. © 2014 by the American college of Sports Medicine.

Heinonen I.,University of Turku | Heinonen I.,Rotterdam University | Heinonen I.,University of Western Australia | Koga S.,Kobe Design University | And 3 more authors.
Exercise and Sport Sciences Reviews | Year: 2015

The systematic increase in VO2 uptake and O2 extraction with increasing work rates conceals a substantial heterogeneity of O2 delivery (QO2)-to-VO2 matching across and within muscles and other organs. We hypothesize that whether increased/decreased QO2/VO2 heterogeneity can be judged as "good" or "bad," for example, after exercise training or in aged individuals or with disease (heart failure, diabetes) depends on the resultant effects on O2 transport and contractile performance. © 2015 by the American College of Sports Medicine.

Amano T.,Kobe University | Ichinose M.,Meiji University | Koga S.,Kobe Design University | Inoue Y.,Osaka International University | And 2 more authors.
Journal of Applied Physiology | Year: 2011

To investigate the effects of different training methods on nonthermal sweating during activation of the muscle metaboreflex, we compared sweating responses during postexercise muscle occlusion in endurance runners, sprinters, and untrained men under mild hyperthermia (ambient temperature, 35°C relative humidity, 50%). Ten endurance runners, nine sprinters, and ten untrained men (maximal oxygen uptakes: 57.5 ± 1.5, 49.3 ± 1.5, and 36.6 ± 1.6 mlkg -1min -1, respectively; P < 0.05) performed an isometric handgrip exercise at 40% maximal voluntary contraction for 2 min, and then a pressure of 280 mmHg was applied to the forearm to occlude blood circulation for 2 min. The δ change in mean arterial blood pressure between the resting level and the occlusion was significantly higher in sprinters than in untrained men (32.2 ± 4.4 vs. 17.3 ± 2.6 mmHg, respectively; P < 0.05); however, no difference was observed between distance runners and untrained men. The Δ mean sweating rate (averaged value of the forehead, chest, forearm, and thigh) during the occlusion was significantly higher in distance runners than in sprinters and untrained men (0.38 ± 0.07, 0.19 ± 0.03, and 0.11 ± 0.04 mgcm -2min -1, respectively; P < 0.05) and did not differ between sprinters and untrained men. Our results suggest that the specificity of training modalities influences the sweating response during activation of the muscle metaboreflex. In addition, these results imply that a greater activation of the muscle metaboreflex does not cause a greater sweating response in sprinters. Copyright © 2011 the American Physiological Society.

Chin L.M.K.,Kobe Design University | Chin L.M.K.,U.S. National Institutes of Health | Kowalchuk J.M.,University of Western Ontario | Barstow T.J.,Kansas State University | And 4 more authors.
Journal of Applied Physiology | Year: 2011

The relationship between muscle deoxygenation and activation was examined in three different muscles of the quadriceps during cycling ramp exercise. Seven young male adults (24 ± 3 yr; mean ± SD) pedaled at 60 rpm to exhaustion, with a work rate (WR) increase of 20 W/min. Pulmonary oxygen uptake was measured breath-by-breath, while muscle deoxygenation (HHb) and activity were measured by timeresolved near-infrared spectroscopy (NIRS) and surface electromyography (EMG), respectively, at the vastus lateralis (VL), rectus femoris (RF), and vastus medialis (VM). Muscle deoxygenation was corrected for adipose tissue thickness and normalized to the amplitude of the HHb response, while EMG signals were integrated (iEMG) and normalized to the maximum iEMG determined from maximal voluntary contractions. Muscle deoxygenation and activation were then plotted as a percentage of maximal work rate (%WR max). The HHb response for all three muscle groups was fitted by a sigmoid function, which was determined as the best fitting model. The c/d parameter for the sigmoid fit (representing the %WR max at 50% of the total amplitude of the HHb response) was similar between VL (47 ± 12% WR max) and VM (43 ± 11% WR max), yet greater (P < 0.05) for RF (65 ± 13% WR max), demonstrating a "right shift" of the HHb response compared with VL and VM. The iEMG also showed that muscle activation of the RF muscle was lower (P < 0.05) compared with VL and VM throughout the majority of the ramp exercise, which may explain the different HHb response in RF. Therefore, these data suggest that the sigmoid function can be used to model the HHb response in different muscles of the quadriceps; however, simultaneous measures of muscle activation are also needed for the HHb response to be properly interpreted during cycle ramp exercise. Copyright © 2011 the American Physiological Society.

Ouchi K.,Kobe Design University | Horita T.,Osaka Prefecture University | Yamada T.,KIT Senior Academy
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2011

The chaotic phase synchronization transition is studied in connection with the zero Lyapunov exponent. We propose a hypothesis that it is associated with a switching of the maximal finite-time zero Lyapunov exponent, which is introduced in the framework of a large deviation analysis. A noisy sine circle map is investigated to introduce this hypothesis and it is tested in an unidirectionally coupled Rössler system by using the covariant Lyapunov vector associated with the zero Lyapunov exponent. © 2011 American Physical Society.

Amano T.,Kobe University | Koga S.,Kobe Design University | Inoue Y.,Osaka International University | Nishiyasu T.,University of Tsukuba | Kondo N.,Kobe University
European Journal of Applied Physiology | Year: 2013

The purpose of this study was to compare sweating function in sprinters who have trained for several years with untrained subjects and trained endurance runners. Two separate experiments were conducted. Nine sprinters, eight untrained men, and nine distance runners (VO2max 50.9 ± 1.4, 38.2 ± 1.8, and 59.1 ± 1.2 mL/kg/min, respectively; P < 0.05) were passively heated for 50 min (Experiment 1), and ten sprinters, 11 untrained men and nine distance runners (similar VO2max levels compared with Experiment 1 in each group) had their sweat gland capacity assessed based on acetylcholine-induced sweating rate (SR) (Experiment 2). The slope of the mean non-glabrous SR plotted against change in mean body temperature during passive heating did not differ significantly between sprinters and untrained men (1.21 ± 0.10 and 0.97 ± 0.12 mg cm-2/min/ C, respectively); in contrast, compared with untrained men, distance runners exhibited a significantly greater slope (1.42 ± 0.11 mg cm-2/min/ C, P < 0.05). The mean body temperature threshold for SR was not significantly different among the groups. Acetylcholine-induced SR did not differ significantly between sprinters and untrained men, whereas distance runners showed a significantly higher induced SR compared with untrained men. The sweating function was not improved in sprinters who have trained 2-3 h/day, 5 days/week, for at least 3 years compared with untrained men, although the VO2max was markedly greater in sprinters. Thus, there is a case that daily training was not sufficient to improve sweating function in sprinters relative to those in distance runners. © 2013 Springer-Verlag Berlin Heidelberg.

Kondo N.,Kobe University | Nishiyasu T.,University of Tsukuba | Inoue Y.,Osaka International University | Koga S.,Kobe Design University
European Journal of Applied Physiology | Year: 2010

This review focuses on the characteristics of heat-loss responses during exercise with respect to non-thermal factors. In addition, the effects of physical training on non-thermal heat-loss responses are discussed. When a subject is already sweating the sweating rate increases at the onset of dynamic exercise without changes in core temperature, while cutaneous vascular conductance (skin blood flow) is temporarily decreased. Although exercise per se does not affect the threshold for the onset of sweating, it is possible that an increase in exercise intensity induces a higher sensitivity of the sweating response. Exercise increases the threshold for cutaneous vasodilation, and at higher exercise intensities, the sensitivity of the skin-blood-flow response decreases. Facilitation of the sweating response with increased exercise intensity may be due to central command, peripheral reflexes in the exercising muscle, and mental stimuli, whereas the attenuation of skin-blood-flow responses with decreased cutaneous vasodilation is related to many non-thermal factors. Most non-thermal factors have negative effects on magnitude of cutaneous vasodilation; however, several of these factors have positive effects on the sweating response. Moreover, thermal and non-thermal factors interact in controlling heat-loss responses, with non-thermal factors having a greater impact until core temperature elevations become significant, after which core temperature primarily would control heat loss. Finally, as with thermally induced sweating responses, physical training seems to also affect sweating responses governed by non-thermal factors. © 2010 Springer-Verlag.

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