Osaka University of Health and Sport Sciences

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Okamoto T.,Kinki University | Masuhara M.,Osaka University of Health and Sport Sciences | Ikuta K.,Osaka Aoyama University
European Journal of Applied Physiology | Year: 2011

Although high-intensity resistance training increases central arterial stiffness, moderate-intensity resistance training does not. However, the effects of low-intensity resistance training on arterial stiffness are unknown. The aim of this study was to investigate the effect of low-intensity resistance training with short inter-set rest period (LSR) on arterial stiffness. Twenty-six young healthy subjects were randomly assigned to training (10 males, 3 females) and control groups (9 males, 4 females). The subjects performed LSR twice a week at 50% of one repetition maximum for 10 weeks. Training consisted of five sets of ten repetitions with an inter-set rest period of 30 s. Changes in brachial-ankle pulse wave velocity (baPWV) and brachial flow-mediated dilation (FMD) were assessed before and after the intervention period. After the intervention period, one repetition maximum strength increased (by 9-38%, P < 0.05 to <0.001; increases varied among the exercise types), baPWV decreased (from 1,093 ± 148 to 1,020 ± 128 cm/s, P < 0.05), and brachial FMD increased (from 9.7 ± 1.3 to 11.8 ± 1.9%, P < 0.05). These values did not change in the control group. These results suggest that LSR reduced arterial stiffness and improved vascular endothelial function. © Springer-Verlag 2010.


Okamoto T.,Nippon Sport Science University | Masuhara M.,Osaka University of Health and Sport Sciences | Ikuta K.,Osaka Aoyama University
International Journal of Sports Medicine | Year: 2013

Although high-intensity resistance training increases arterial stiffness, low-intensity resistance training reduces arterial stiffness. The present study investigates the effect of low-intensity resistance training before and after high-intensity resistance training on arterial stiffness. 30 young healthy subjects were randomly assigned to a group that performed low-intensity resistance training before high-intensity resistance training (BLRT, n=10), a group that performed low-intensity resistance training after high-intensity resistance training (ALRT, n=10) and a sedentary control group (n=10). The BLRT and ALRT groups performed resistance training at 80% and 50% of one repetition maximum twice each week for 10 wk. Arterial stiffness was measured using carotid-femoral and femoral-ankle pulse wave velocity (PWV). One-repetition maximum strength in the both ALRT and BLRT significantly increased after the intervention (P<0.05 to P<0.01). Both carotid-femoral PWV and femoral-ankle PWV after combined training in the ALRT group did not change from before training. In contrast, carotid-femoral PWV after combined training in the BLRT group increased from before training (P <0.05). Femoral-ankle PWV after combined training in the both BLRT and ALRT groups did not change from before training. These results suggest that although arterial stiffness is increased by low-intensity resistance training before high-intensity resistance training, performing low-intensity resistance training thereafter can prevent the increase of arterial stiffness. © Georg Thieme Verlag KG Stuttgart · New York.


Okamoto T.,Nippon Sport Science University | Masuhara M.,Osaka University of Health and Sport Sciences | Ikuta K.,Osaka Aoyama University
Journal of Strength and Conditioning Research | Year: 2014

Flexibility is associated with arterial distensibility. Many individuals involved in sport, exercise, and/or fitness perform self-myofascial release (SMR) using a foam roller, which restores muscles, tendons, ligaments, fascia, and/or soft-tissue extensibility. However, the effect of SMR on arterial stiffness and vascular endothelial function using a foam roller is unknown. This study investigates the acute effect of SMR using a foam roller on arterial stiffness and vascular endothelial function. Ten healthy young adults performed SMR and control (CON) trials on separate days in a randomized controlled crossover fashion. Brachial-ankle pulse wave velocity (baPWV), blood pressure, heart rate, and plasma nitric oxide (NO) concentration were measured before and 30 minutes after both SMR and CON trials. The participants performed SMR of the adductor, hamstrings, quadriceps, iliotibial band, and trapezius. Pressure was selfadjusted during myofascial release by applying body weight to the roller and using the hands and feet to offset weight as required. The roller was placed under the target tissue area, and the body was moved back and forth across the roller. In the CON trial, SMR was not performed. The baPWV significantly decreased (from 1,202 ± 105 to 1,074 ± 110 cms-1) and the plasma NO concentration significantly increased (from 20.4 ± 6.9 to 34.4 ± 17.2 mmol L-1) after SMR using a foam roller (both p< 0.05), but neither significantly differed after CON trials. These results indicate that SMR using a foam roller reduces arterial stiffness and improves vascular endothelial function. © 2013 National Strength and Conditioning Association.


Ando S.,Osaka University of Health and Sport Sciences | Ando S.,Kyoto Prefectural University of Medicine | Yamada Y.,Kyoto University | Kokubu M.,Kyoto University
Journal of Applied Physiology | Year: 2010

The purpose of this study was to test the hypothesis that decrease in cerebral oxygenation compromises an individual's ability to respond to peripheral visual stimuli during exercise. We measured the simple reaction time (RT) to peripheral visual stimuli at rest and during and after cycling at three different workloads [40%, 60%, and 80% peak oxygen uptake (V̇o2)] under either normoxia [inspired fraction of oxygen (FIo2) = 0.21] or normobaric hypoxia (FIo2 = 0.16). Peripheral visual stimuli were presented at 10° to either the right or the left of the midpoint of the eyes. Cerebral oxygenation was monitored during the RT measurement over the right frontal cortex with near-infrared spectroscopy. We used the premotor component of RT (premotor time) to assess effects of exercise on the central process. The premotor time was significantly longer during exercise at 80% peak V̇o2 (normoxia: 214.2 ± 33.0 ms, hypoxia: 221.5 ± 30.1 ms) relative to that at rest (normoxia: 201.0 ± 27.2 ms, hypoxia: 202.9 ± 29.7 ms) (P < 0.01). Under normoxia, cerebral oxygenation gradually increased up to 60% peak V̇o2 and then, decreased to the resting level at 80% peak V̇o2. Under hypoxia, cerebral oxygenation progressively decreased as exercise workload increased. We found a strong correlation between increase in premotor time and decrease in cerebral oxygenation (r2 = 0.89, P < 0.01), suggesting that increase in premotor time during exercise is associated with decrease in cerebral oxygenation. Accordingly, exercise at high altitude may compromise visual perceptual performance. Copyright © 2010 the American Physiological Society.


Shimokochi Y.,Osaka University of Health and Sport Sciences | Ambegaonkar J.P.,George Mason University | Meyer E.G.,Lawrence Technological University | Lee S.Y.,Yonsei University | Shultz S.J.,University of North Carolina at Greensboro
Knee Surgery, Sports Traumatology, Arthroscopy | Year: 2013

Purpose: To examine the effects of different sagittal plane body positions during single-leg landings on biomechanics and muscle activation parameters associated with risk for anterior cruciate ligament (ACL) injury. Methods: Twenty participants performed single-leg drop landings onto a force plate using the following landing styles: self-selected, leaning forward (LFL) and upright (URL). Lower extremity and trunk 3D biomechanics and lower extremity muscle activities were recorded using motion analysis and surface electromyography, respectively. Differences in landing styles were examined using 2-way Repeated-measures ANOVAs (sex × landing conditions) followed by Bonferroni pairwise comparisons. Results: Participants demonstrated greater peak vertical ground reaction force, greater peak knee extensor moment, lesser plantar flexion, lesser or no hip extensor moments, and lesser medial and lateral gastrocnemius and lateral quadriceps muscle activations during URL than during LFL. These modifications of lower extremity biomechanics across landing conditions were similar between men and women. Conclusions: Leaning forward while landing appears to protect the ACL by increasing the shock absorption capacity and knee flexion angles and decreasing anterior shear force due to the knee joint compression force and quadriceps muscle activation. Conversely, landing upright appears to be ACL harmful by increasing the post-impact force of landing and quadriceps muscle activity while decreasing knee flexion angles, all of which lead to a greater tibial anterior shear force and ACL loading. ACL injury prevention programmes should include exercise regimens to improve sagittal plane body position control during landing motions. © 2012 Springer-Verlag.


Takimoto M.,Osaka University of Health and Sport Sciences | Hamada T.,Osaka University of Health and Sport Sciences
Journal of Applied Physiology | Year: 2014

The brain is capable of oxidizing lactate and ketone bodies through monocarboxy-late transporters (MCTs). We examined the protein expression of MCT1, MCT2, MCT4, glucose transporter 1 (GLUT1), and cyto-chrome-c oxidase subunit IV (COX IV) in the rat brain within 24 h after a single exercise session. Brain samples were obtained from sedentary controls and treadmill-exercised rats (20 m/min, 8% grade). Acute exercise resulted in an increase in lactate in the cortex, hippocampus, and hypothalamus, but not the brainstem, and an increase in ß-hydroxybutyrate in the cortex alone. After a 2-h exercise session MCT1 increased in the cortex and hippocampus 5 h postexercise, and the effect lasted in the cortex for 24 h postexercise. MCT2 increased in the cortex and hypothalamus 5-24 h postexercise, whereas MCT2 increased in the hippocampus immediately after exercise, and remained elevated for 10 h postexercise. Regional upregulation of MCT2 after exercise was associated with increases in brain-derived neurotrophic factor and tyrosine-related kinase B proteins, but not insulin-like growth factor 1. MCT4 increased 5-10 h postexercise only in the hypothalamus, and was associated with increased hypoxia-inducible factor-1a expression. However, none of the MCT isoforms in the brainstem was affected by exercise. Whereas GLUT 1 in the cortex increased only at 18 h postexercise, COX IV in the hippocampus increased 10 h after exercise and remained elevated for 24 h postexercise. These results suggest that acute prolonged exercise induces the brain region-specific upregulation of MCT1, MCT2, MCT4, GLUT1, and COX IV proteins. Copyright © 2014 the American Physiological Society.


Ohta Y.,Osaka University of Health and Sport Sciences | Shima N.,Tokai Gakuen University | Yabe K.,Osaka University of Health and Sport Sciences
Journal of Biomechanics | Year: 2010

The purpose of this study was to determine the changes that occur in tendinous tissue properties during the early phase of tetanic summation in the in vivo human tibialis anterior muscle (TA). The torque response and tendinous tissue elongation following single stimuli, two-pulse trains, and three-pulse trains were recorded in the TA during isometric contractions. The elongation, compliance, and lengthening velocity of tendinous tissue were determined by real-time ultrasonography. The contribution of the response to the second stimulation (C2) was obtained by subtracting the response to the single stimulation (C1) from the response of doublet. The third contribution (C3) was obtained by subtracting the response to the doublet from that of the triplet. C2 (7.8±0.5 Nm) and C3 (7.3±0.6 Nm) had torque responses significantly higher than C1 (3.6±0.7 Nm). In contrast, the elongations of tendinous tissue for C2 (2.8±0.4 mm) and C3 (1.7±0.2 mm) were significantly lower than for C1 (4.9±0.3 mm), indicating that the summation pattern of tendinous tissue elongation is different from the summation pattern of torque response. In addition, this showed considerable difference both between C1 (0.12±0.01 mm/N; 83±4.6 mm/s) and C2 (0.03±0.005 mm/N; 50±6.3 mm/s) and between C1 and C3 (0.02±0.002 mm/N; 39±6.4 mm/s) in the compliance and lengthening velocity of tendinous tissue. These results suggest that changes in tendinous tissue properties between first and second contraction are related to different summation patterns of force and tendinous tissue elongation during early phase of tetanic summation. © 2009 Elsevier Ltd. All rights reserved.


Shimokochi Y.,Osaka University of Health and Sport Sciences | Ide D.,Gamba Osaka Academy | Kokubu M.,Osaka University of Health and Sport Sciences | Nakaoji T.,Osaka University of Health and Sport Sciences
Journal of Strength and Conditioning Research | Year: 2013

Basketball players have to move laterally and quickly change their movement directions, especially during defensive moves. This study aimed to investigate how frontal and sagittal plane hip movements relate to fastness and quickness of lateral cutting maneuvers from sliding. Three-dimensional biomechanical data were obtained for 28 female college basketball players while they performed lateral cutting maneuvers using their left leg after 2 lateral sliding steps. The lateral cutting index (LCIndex) expressing fastness and quickness of lateral cutting maneuvers, peak hip abduction and extension velocities immediately before foot contact, hip abduction and extension velocities at foot contact, peak horizontal ground reaction force, frontal plane ground reaction force angle, and sacrum center of mass position were calculated. Simple and stepwise regression analyses were conducted to predict LCIndex. The former showed that greater maximum hip extension velocity (p = 0.03) and lesser hip abduction velocity (p = 0.04) as well as smaller ground reaction force angle (p = 0.001) and lower sacrum center of mass position (p = 0.001) at foot contact led to better LCIndex. The latter showed that sacrum center of mass position at foot contact and hip extension velocity explained 35.3% (p < 0.01) and 7.3% (p = 0.088) of variance in LCIndex, respectively. Our results did not suggest that hip abductor function is important for lateral sliding moves, instead suggesting that faster hip extension motions to kick the ground and lowering the body center of mass are crucial for better lateral decelerationacceleration motions. © 2013 National Strength and Conditioning Association.


Sasaki Y.,Osaka University of Health and Sport Sciences
Communications in Number Theory and Physics | Year: 2012

The Witten zeta-functions associated with semisimple Lie algebras were defined by Zagier, and their special values at even positive integers were first studied by Witten in connection with quantum gauge theory. In this paper, relations between multiple higher Mahler measures for some families of polynomials and special values of Witten zeta-functions at positive integers are showed. Consequently, a geometrical interpretation of the multiple higher Mahler measure as the volume of certain moduli space is given.


Takimoto M.,Osaka University of Health and Sport Sciences | Takeyama M.,Osaka University of Health and Sport Sciences | Hamada T.,Osaka University of Health and Sport Sciences
Metabolism: Clinical and Experimental | Year: 2013

Objective The regulatory mechanisms responsible for acute exercise-induced expression of monocarboxylate transporters MCT1 and MCT4 mRNA in skeletal muscle remain unclear. 5′-adenosine-activated protein kinase (AMPK) is a key signaling molecule that regulates gene expression at the mRNA level. We examined whether AMPK activation is involved in acute exercise-induced expression of MCT1 and MCT4 mRNA in fast-twitch muscle. Materials/Methods Male Sprague-Dawley rats were subjected to an acute bout of either 5 min high-intensity intermittent swimming (HIS) or 6-h low-intensity prolonged swimming (LIS). The effects of acute exercise on the phosphorylation of AMPK (p-AMPK), calcium/calmodulin pendent kinase II (p-CaMKII), p38 mitogen-activated protein kinase (p-p38MAPK), and MCTs mRNA were analyzed in vivo. To observe the direct effects of AMPK activation on MCTs mRNA, the effects of 5-aminoimidazole-4-carboxamide-1-beta-D- ribofuranoside (AICAR), caffeine, and dantrolene were analyzed in vitro using an isolated muscle incubation model. Results The p-AMPK increased in response to both HIS and LIS, although the p-CaMKII and p-p38MAPK were increased only following HIS. Irrespective of exercise intensity, MCT1 and MCT4 mRNA was also transiently upregulated by both HIS and LIS. Direct exposure of the epitrochlearis muscle to 0.5 mmol/L AICAR or 1 mmol/L caffeine, which activated p-AMPK increased both MCT1 and MCT4 mRNA levels. When pAMPK was inhibited by dantrolene, neither MCT1 nor MCT4 mRNA was increased. Conclusion These results suggest that acute exercise-induced increases in MCT1 and MCT4 mRNA expression may be possibly mediated by AMPK activation, at least in part in fast-twitch muscle. © 2013 Elsevier Inc.

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