Mikio Hiura - Academia.edu (original) (raw)

Papers by Mikio Hiura

Frontiers in Physiology

Purpose: The present study used near-infrared spectroscopy to investigate the relationships betwe... more Purpose: The present study used near-infrared spectroscopy to investigate the relationships between cerebral oxygen metabolism and perfusion in the prefrontal cortex (PFC) during exercises of different intensities.Methods: A total of 12 recreationally active men (age 24 ± 6 years) were enrolled. They performed 17 min of low-intensity exercise (ExL), followed by 3 min of moderate-intensity exercise (ExM) at constant loads. Exercise intensities for ExL and ExM corresponded to 30% and 45% of the participants’ heart rate reserve, respectively. Cardiovascular and respiratory parameters were measured. We used near-infrared time-resolved spectroscopy (TRS) to measure the cerebral hemoglobin oxygen saturation (ScO2) and total hemoglobin concentration ([HbT]), which can indicate the cerebral blood volume (CBV). As the cerebral metabolic rate for oxygen (CMRO2) is calculated using cerebral blood flow (CBF) and ScO2, we assumed a constant power law relationship between CBF and CBV based on inv...

Medicine and Science in Sports and Exercise, May 1, 2006

Walking ability is an important factor for independent living, and its evaluation method using li... more Walking ability is an important factor for independent living, and its evaluation method using limited space is required in clinical practice and research. Here, we examined the validity of the stepping exercise at using three types of rhythm (80, 110, and 140 bpm) as an assessment tool for measuring walking ability in older people. We measured lower-limb muscular power, maximal and preferred walking speed, and ground reaction force in older people performing a chair stand test、6m walking test, and stepping exercise test, respectively. Ground reaction force at stepping with the rhythm of 110 bpm correlated significantly with maximal walking speed. In conclusion, the ground reaction force obtained from the stepping exercise test using the rhythm of 110 bpm could be useful to assess the walking ability in older people. Keyword: rhythm exercise, locomotive

法政大学スポーツ健康学研究, Mar 30, 2013

BMJ Open Sport & Exercise Medicine

Non-communicable diseases (NCDs), including coronary heart disease, stroke, hypertension, type 2 ... more Non-communicable diseases (NCDs), including coronary heart disease, stroke, hypertension, type 2 diabetes, dementia, depression and cancers, are on the rise worldwide and are often associated with a lack of physical activity (PA). Globally, the levels of PA among individuals are below WHO recommendations. A lack of PA can increase morbidity and mortality, worsen the quality of life and increase the economic burden on individuals and society. In response to this trend, numerous organisations came together under one umbrella in Hamburg, Germany, in April 2021 and signed the ‘Hamburg Declaration’. This represented an international commitment to take all necessary actions to increase PA and improve the health of individuals to entire communities. Individuals and organisations are working together as the ‘Global Alliance for the Promotion of Physical Activity’ to drive long-term individual and population-wide behaviour change by collaborating with all stakeholders in the community: activ...

Frontiers in Physiology, 2022

PurposeThis study aimed to investigate changes in cerebral hemodynamics and oxygenation at modera... more PurposeThis study aimed to investigate changes in cerebral hemodynamics and oxygenation at moderate, heavy, maximal and supramaximal intensities of rowing exercise. It also examined whether these changes reflect alterations in sensation of effort and mood. We also aimed to examine the effects of peak pulmonary oxygen consumption (V.O2peak) on cerebral oxygenation.MethodsEleven rowers, consisting out of six athletes and five recreational rowers [two female; age, 27 ± 9 years; height, 171 ± 7 cm, body mass, 67 ± 9 kg; V.O2peak, 53.5 ± 6.5 mL min–1 kg–1] rowed a 13-min session separated by 10 and 3 min, at 70 (Ex70%) and 80% of V.O2peak (Ex80%), respectively, on a rowing ergometer, followed by three sessions of 1-min supramaximal exercise (ExSp). After a warm-up at 60% of V.O2peak (ExM), seven male rowers performed a 2,000 m all-out test (Ex2000). Cardiovascular and respiratory variables were measured. Cerebral oxygenation was investigated by near-infrared time-resolved spectroscopy (T...

Advances in Experimental Medicine and Biology, 2018

Neuronal activity causes changes in both cerebral metabolic rate of oxygen (CMRO2) and cerebral b... more Neuronal activity causes changes in both cerebral metabolic rate of oxygen (CMRO2) and cerebral blood flow (CBF). Since the relationship between tissue oxygenation and regional CBF (rCBF) during exercise has not been elucidated, we compared the data obtained using near-infrared spectroscopy (NIRS) and rCBF examined using positron emission tomography (PET). Participants in this study comprised 26 healthy young men. Changes in concentration of oxygenated hemoglobin (ΔO2Hb) and deoxygenated hemoglobin (ΔHHb) in the prefrontal cortex (PFC) were measured using NIRS continuously during a 15-min bout of the constant-load low-intensity cycling exercise (n = 14). Under the same protocol as the NIRS study, rCBF was measured using H215O and PET by the autoradiographic method at baseline (Rest) and at 3 min (Ex1) and 13 min (Ex2) after starting exercise (n = 12). As systematic factors influenced by exercise, heart rate, end-tidal pressure of carbon dioxide (PETCO2) and blood pressure (BP) were monitored. For each region investigated by NIRS, rCBF was analyzed quantitatively using PET-MRI co-registered standardized images. Despite inter-individual differences, changing patterns of ΔO2Hb and ΔHHb in the PFC were similar between channels. Significant main effects for time point were identified in ΔO2Hb, ΔHHb and changes in rCBF. While rCBF increased from rest, ΔO2Hb was not changed at Ex1. Conversely, rCBF was unchanged from rest but ΔO2Hb was significantly increased at Ex2. Fluctuations of PETCO2 and BP evoked by exercise were not in accordance with changes in ΔO2Hb, ΔHHb and rCBF, while BP may affect the forehead skin blood flow. Given that NIRS data are a mixture of skin and brain effects, our results suggest that CMRO2 may differ between the phases in a bout of dynamic exercise. The present study indicates the utility of NIRS to examine the relationship between CMRO2 and rCBF during exercise.

International journal of sports medicine, Jan 22, 2018

Dynamic exercise elicits fluctuations in blood pressure (BP) and cerebral blood flow (CBF). This ... more Dynamic exercise elicits fluctuations in blood pressure (BP) and cerebral blood flow (CBF). This study investigated responses in BP and CBF during cycling exercise and post-exercise hypotension (PEH) using positron emission tomography (PET). CBF was measured using oxygen-15-labeled water (HO) and PET in 11 human subjects at rest (Rest), at the onset of exercise (Ex1), later in the exercise (Ex2), and during PEH. Global CBF significantly increased by 13% at Ex1 compared with Rest, but was unchanged at Ex2 and during PEH. Compared with at Rest, regional CBF (rCBF) increased at Ex1 (20~42%) in the cerebellar vermis, sensorimotor cortex for the bilateral legs (M1and S1), insular cortex and brain stem, but increased at Ex2 (28~31%) only in the vermis and M1and S1. During PEH, rCBF decreased compared with Rest (8~13%) in the cerebellum, temporal gyrus, piriform lobe, thalamus and pons. The areas showing correlations between rCBF and mean BP during exercise and PEH were consistent with the...

The Proceedings of the Dynamics & Design Conference, 2004

In thi ∬ 加 dy ， the shaldng of center of pressure， reaction force ， and EMG Qf Iower − llmb were ... more In thi ∬ 加 dy ， the shaldng of center of pressure， reaction force ， and EMG Qf Iower − llmb were measured fbr several seat heights dudng 鋤 d − movernent ． Sixteen young adult m 颱 s 呵 ectS ・ partieipated in this study ． The su 句 ects pe 面 e 磁 and 皿 ovement 加 m chair with the helghts 呻 5胎 d to − 6cm ， − 3cm ，＋3cm and ＋6cm 恥皿 eptimu 皿 seat height ． The subjeets performed stand mevement with and whhout senior person mock experience eqUiptnent The chair optimum hclght produced less shaking of the cefiter ef pressure ． Kay mordS ． Center ofpressure ， Seat height ， Staridmovement ， Sensory evaluation

Japanese Journal of Neurosurgery, 2011

Introduct 量 on ： Higher brain dysfunction is the major problem of patients who recover fro エ n ne... more Introduct 量 on ： Higher brain dysfunction is the major problem of patients who recover fro エ n neurotrauma the prevents them from returning to their previous social life ． Many such patients do not have f6cal brain damage detected with moXphological imaging ． We focused on studying the focal brain dysfunction that can be detected only with functional imaging with positron emission tomography (PET)in relation to the score of various cogni − tion batteries ， Methods ； Patients who complain of higher brain dysfunction without apparent morphoiogical cortical dam − age were recrllited f6r this study Thirteen patients with diffUse axonal injury (DAI ＞ or cerebral concussion was included ． They underwent a PET study to image ： 1)glucose metabolis 皿 b ジ呂 F − FDG ， and 2)central benodi − azepine receptor (cBZD − R ＞(marker of neuronal body)by nC − fiumazenil ， together with cognition measurement by W △IS − R ， WMS − R ， and WCST etc ， PET data were cornpared with age matched normal controls using SPM2 ． Results： 1)DAI patients had a sign 丗cant decrease in glucose matabolism and cBZD − R distribution in the cingulated cortex than normal controls ． 2) Patients diagnosed with concussion because of shorter consciousness disturbance also had abnormal FDG uptake and cBZD − R distribution ．3)Cognition test scores were va エiable among patients ． Degree of decreased glucose metabolism and cBZD − R distribution in the dominant hemishphere corresponded we11 匸 o the severity of cognitive disturbance ． Conclusions ： PET molecular imaging was useful to depict focal cortical dysfunction of neurotrauma patients even when morphological change was not apparent ． This method may be promising to clarify the patho − physiology of higher brain dysfunction of patients with diffuse axonal injury or chronic trau エ natic encephalopathy (

Medicine & Science in Sports & Exercise, 2017

METHODS: Healthy men (n = 11, 28 yrs, BMI = 24.6) and women (n = 9, 25 yrs, BMI = 23.2) performed... more METHODS: Healthy men (n = 11, 28 yrs, BMI = 24.6) and women (n = 9, 25 yrs, BMI = 23.2) performed RE (3 sets of 10 repetitions of isokinetic concentric/concentric unilateral knee flexion/extension). Measurements were obtained at baseline and post-exercise (1, 5, 30 min). Beat-to-beat heart rate (HR), brachial BP (bSBP, bDBP, bMAP), cardiac output (CO), stroke volume (SV) and end-tidal CO2 were collected. CBFv was measured by transcranial Doppler. Carotid BP (cSBP, cDBP, cMAP) measurements were obtained using applanation tonometry. Central pulse wave velocity (PWV) was measured by an automated ambulatory BP monitor. RESULTS: See table. Mean CBFv increased 1-min post-exercise and decreased below baseline 5-min post-exercise (p<0.01) in both groups. CBFv pulsatility increased following RE and was elevated above baseline 5-min post-exercise (p<0.01) in both groups. PWV increased 1-min post-exercise (p<0.01) in both groups. Most variables returned to baseline at 30 min. CONCLUSION: RE increased central arterial stiffness, mean CBFv and CBFv pulsatility similarly for both sexes. Although CO increased at 5-min, CBFv dropped below baseline and pulsatility continued to rise above baseline. This temporary disruption in cerebral autoregulation may impact brain health in both sexes.

BMC Sports Science, Medicine and Rehabilitation, 2015

Cerebral Blood Flow and Metabolism (Japanese journal of cerebral blood flow and metabolism), 2017

PET imaging for altered brain function evoked by exercise: measurements of changes in cerebral bl... more PET imaging for altered brain function evoked by exercise: measurements of changes in cerebral blood flow and neurotransmitters

Internal Medicine Review, 2016

&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;... more &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;tt&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;We investigated the changes in cerebral perfusion during constant low-intensity exercise and the effect of a late increase in workload. Eleven healthy males participated in this study. Four subjects performed 15 min of constant low-intensity exercise on a cycle ergometer, while seven subjects performed 20 min of exercise consisting of 17 min of low-intensity exercise, which was incremented to moderate-intensity for the final 3 min. As an index for cerebral perfusion, the time-averaged mean velocity of flow in the middle cerebral artery (MCAV&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;sub&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;mean&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/sub&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;) was measured using transcranial Doppler ultrasound. During the 15-min of low-intensity exercise (78 ± 3 Watts), pulmonary oxygen consumption…

International journal of sports medicine, 2017

The central opioid receptor system likely contributes to the mechanism underlying the changes in ... more The central opioid receptor system likely contributes to the mechanism underlying the changes in affect elicited by exercise. Our aim was to use positron emission tomography (PET) to test whether exercise intensity influences activation of the μ-opioid receptor system in the brain, and whether changes in opioid receptor activation correlate with exercise-induced changes in affect. 7 healthy young male subjects (23±2 years) performed 20-min constant-load cycling exercises at heavy (ExH) and severe-intensity (ExS), and PET was performed using [(11)C]carfentanil as a tracer before and after each exercise. Exercise elicited the μ-opioidergic system activation in the large areas of the limbic system, particularly in the insular cortex, and cerebellum. Of note, deactivation of the μ-opioidergic system in the pituitary gland was identified as a specific finding in ExS, which evoked a distinctive sensation of fatigue. Within these brain areas, μ-opioid receptor activation correlated positiv...