Publications by authors named "Toshiyuki Kurihara"

66 Publications

Change of Direction Speed Tests in Basketball Players: A Brief Review of Test Varieties and Recent Trends.

Front Sports Act Living 2021 29;3:645350. Epub 2021 Apr 29.

Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan.

Change of direction speed (CODS) is essential for basketball performance, extensively assessed by various tests. This review aimed to summarize the CODS test varieties for basketball players on publications until 2019 and identify recent trends regarding what types of tests have gained attention in the 2010s. Electronic literature searches were conducted using three databases with relevant keywords. 104 studies were found eligible, conducting CODS tests 159 times in total with 48 test varieties. To facilitate distinctions between the tests, each test was categorized into one of three types based on the distinctive movement characteristics and changing angles as follows: Defensive (involving lateral shuffling), 180°-turn (exerting only 180°-turns), and Cutting (performing diagonal- or side-cut). We then counted the number of publications and adopted times reported per year for each test, and calculated the adoption rate for each categorized test type. The first CODS test performed in basketball players was the -Test, reported in 1991, and this was the most commonly adopted test (44/159 times). The 2010s saw abrupt increases in the number of publications (1990s-2000s-2010s: 5-9-90) and test varieties (4-7-44). The adoption rates in the 2010s were similar among the three types (i.e., Defensive/180°-turn/Cutting: 37%/30%/33%), with the Cutting type gradually increasing over the last three decades (1990s-2000s-2010s: 0%-9%-33%). These results suggest that while CODS performances in basketball players are increasingly studied with various tests, recent studies give equal weight to all of the three categorized test types, with increasing adoption of the Cutting type, to assess specific CODS performances.
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http://dx.doi.org/10.3389/fspor.2021.645350DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8117963PMC
April 2021

Toe flexor strength is associated with mobility in older adults with pronated and supinated feet but not with neutral feet.

J Foot Ankle Res 2020 Sep 11;13(1):55. Epub 2020 Sep 11.

Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan.

Background: Older adults are known to have more pronated foot posture and decreased toe flexor strength (TFS), as well as decreased mobility in daily life compared to young adults. Although foot posture is reported to be an influential factor for walking biomechanics in young adults, there is less information on this subject in older adults. Age-related reduction in TFS is shown to be associated with impairments of functional performance, but it is poorly understood whether foot posture influences the relationships between TFS and functional performances. Therefore, the present study aimed to elucidate this concern by examining older women.

Methods: Seventy community-dwelling older women (76.8 ± 4.4 years) voluntarily participated in this study. Foot posture was evaluated by the 6-item foot posture index (FPI). Based on the FPI score, participants were allocated to pronated, neutral, or supinated group (n = 33, 26, and 11, respectively). TFS was assessed using a toe grip dynamometer in a seated position. Scores of 30-s chair stand, timed up-and-go, 5-m comfortable-speed walking, and static balance tests were determined to evaluate functional performances. Pearson's correlation coefficients were computed to examine the relationships between TFS and functional performances in each group.

Results: TFS positively correlated with comfortable walking speed in the pronated (r = 0.37, p = 0.03) and supinated (r = 0.76, p < 0.001) groups, but not in the neutral group (r = 0.17, p = 0.42). For the two significant relationships, an analysis of covariance showed that there was no significant difference between the pronated and supinated groups in the slopes of the regression lines, suggesting a similar relative contribution of TFS to comfortable walking speed between the two groups. In addition, TFS tended to negatively correlate with timed up-and-go time in the pronated (r = - 0.32, p = 0.07) and supinated (r = - 0.56, p = 0.08) groups, and positively correlate with 30-s chair stand score in the pronated group (r = 0.31, p = 0.08).

Conclusions: The present study indicates that TFS would be associated with mobility, walking performance in particular, in older women with pronated and supinated feet but not with neutral feet.
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http://dx.doi.org/10.1186/s13047-020-00422-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7488436PMC
September 2020

Decreased Muscle Strength of Knee Flexors is Associated with Impaired Muscle Insulin Sensitivity in Non-Diabetic Middle-Aged Japanese Male Subjects.

Diabetes Ther 2020 Oct 7;11(10):2401-2410. Epub 2020 Aug 7.

Sportology Center, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.

Introduction: Reduced muscle strength is a high risk factor for type 2 diabetes mellitus, and this association is especially strong in non-obese male individuals. However, it remains unclear how reduced muscle strength affects susceptibility to diabetes. We have examined whether lower limb muscle strength is associated with insulin resistance in non-obese Japanese male subjects.

Methods: Measurements from 64 non-diabetic, non-obese, middle-aged Japanese men were analyzed. Insulin sensitivity in muscle was measured using the hyperinsulinemic-euglycemic clamp. Isometric muscle strength of the knee extensor and flexor muscles was evaluated using a dynameter.

Results: Lower muscle strength of knee flexors, but not knee extensors, was associated with impaired muscle insulin sensitivity (knee flexor muscles: low, medium, and high strength was 6.6 ± 2.2, 7.3 ± 2.0, and 8.8 ± 2.2 mg/kg per minute, respectively, p for trend < 0.05; knee extensor muscles: low, medium, and high strength was 7.3 ± 2.5, 7.5 ± 2.2, and 7.8 ± 2.3 mg/kg per minute, respectively, p for trend = 0.73). Knee flexor muscle strength was also identified as an independent determinant of insulin sensitivity in the multiple regression analysis (β = 0.274, p = 0.036).

Conclusions: Diminished strength of knee flexor muscles, but not knee extensor muscles, was associated with muscle insulin sensitivity in non-diabetic, non-obese Japanese male subjects.
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http://dx.doi.org/10.1007/s13300-020-00895-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7509026PMC
October 2020

Lycopene-Family Carotenoids Confer Thermostability on Photocomplexes from a New Thermophilic Purple Bacterium.

Biochemistry 2020 06 15;59(25):2351-2358. Epub 2020 Jun 15.

Department of Agrobioscience, Graduate School of Agriculture, Kobe University, Nada, Kobe 657-8501, Japan.

is a newly described thermophilic purple bacterium containing bacteriochlorophyll . Using purified light-harvesting 1 reaction center (LH1-RC) core complexes from . , we compared the biochemical, spectroscopic, and thermal denaturation properties of these complexes with those of its mesophilic counterpart, . Besides their growth temperature optima, a striking difference between the two species was seen in the carotenoid composition of their LH1-RC complexes. The more thermostable . complex contained more carotenoids with longer conjugation lengths ( > 9), such as lycopenes ( = 11), and had a total carotenoid content significantly higher than that of the complex, irrespective of the light intensity used for growth. The thermostability of LH1-RCs from both and decreased significantly in cells grown in the presence of diphenylamine, a compound that inhibits the formation of highly conjugated carotenoids. In contrast to the thermophilic purple bacterium , where Ca is essential for LH1-RC thermostability, Ca neither was present in nor had any effect on the thermostability of the . LH1-RC. These results point to a mechanism that carotenoids with elongated conjugations enhance hydrophobic interactions with proteins in the LH1-RC, thereby allowing the complexes to withstand thermal denaturation. This conclusion is bolstered by a structural model of the LH1-RC and is the first example of photocomplex thermostability being linked to a carotenoid-based mechanism.
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http://dx.doi.org/10.1021/acs.biochem.0c00192DOI Listing
June 2020

Adverse effects of the coexistence of locomotive syndrome and sarcopenia on the walking ability and performance of activities of daily living in Japanese elderly females: a cross-sectional study.

J Phys Ther Sci 2020 Mar 11;32(3):227-232. Epub 2020 Mar 11.

Faculty of Sport and Health Science, Ritsumeikan University: 1-1-1 Noji Higashi, Kusatsu, Shiga 525-8577, Japan.

[Purpose] The aim of this study was to investigate whether the coexistence of locomotive syndrome and sarcopenia is associated with the risk of fall or performance of activities of daily living in elderly females. [Participants and Methods] We categorized 112 Japanese elderly female participants under three groups: control, locomotive syndrome, and locomotive syndrome and co-existing sarcopenia. We compared the groups based on the mean scores of anthropometric and physical function measurements, the Timed Up and Go test, and the Tokyo Metropolitan Institute of Gerontology Index of Competence to evaluate activities of daily living. [Results] The Timed Up and Go test score significantly differed among the groups. The score of the Timed Up and Go test significantly correlated with scores of the skeletal muscle mass index, skeletal muscle strength grading, and usual gait speed. The total score of the Tokyo Metropolitan Institute of Gerontology Index of Competence significantly decreased in all the groups. [Conclusion] The coexistence of locomotive syndrome and sarcopenia is associated with an increased risk of fall and worsened performance of activities of daily living. Further, the risk of fall is associated with the skeletal muscle mass, skeletal muscle strength, and gait speed. It seems likely that, compared to sarcopenia, locomotive syndrome is more sensitive to lower limb dysfunctions.
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http://dx.doi.org/10.1589/jpts.32.227DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7064352PMC
March 2020

Associations among Bone Mineral Density, Physical Activity and Nutritional Intake in Middle-Aged Women with High Levels of Arterial Stiffness: A Pilot Study.

Int J Environ Res Public Health 2020 03 3;17(5). Epub 2020 Mar 3.

College of Sport and Health Science, Ritsumeikan University, Shiga 525-8577, Japan.

There is little consensus regarding the impacts of physical activity and nutrient intake on bone mineral density (BMD) in subjects with high or low levels of arterial stiffness. This study was performed to investigate whether physical activity and nutrient intake are associated with BMD in middle-aged women with high levels of arterial stiffness. The study population consisted of middle-aged women aged 40-64 years ( = 22). BMD was assessed by dual-energy X-ray absorptiometry. Carotid-femoral pulse wave velocity (cf-PWV) was used as an indicator of arterial stiffness. Subjects were divided into two groups by median cf-PWV. Physical activity in free-living conditions was evaluated using a triaxial accelerometer. Nutrient intake was also measured using the brief-type self-administered diet history questionnaire. In the High-PWV group, BMD showed a significant negative correlation with age. Using a partial correlation model, BMD was associated with the number of steps and unsaturated fatty acid intake in the High-PWV group. These results suggest that BMD in middle-aged women with high levels of arterial stiffness may be associated with both the number of steps and nutritional intake. Recommendations of physical activity and nutritional intake for the prevention of osteopenia should include consideration of arterial stiffness.
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http://dx.doi.org/10.3390/ijerph17051620DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7084750PMC
March 2020

Relationship between Trunk Muscularity and Club Head Speed in Male Golfers.

Int J Sports Med 2020 Jun 11;41(6):419-423. Epub 2020 Feb 11.

Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Japan.

This study examined how the volume of trunk muscles and its bilateral asymmetry are related to club head speed in golfers. Fourteen right-handed male golfers performed five driver shots, and the club head speed for each trial was calculated from a three-dimensional reflective marker position of the club head immediately before impact. The volume of each side of the rectus abdominis, erector spinae, psoas major, quadratus lumborum, lateral abdominal wall muscle, and multifidus was determined using magnetic resonance imaging. For each muscle, the ratio of the larger to smaller side in muscle volume was calculated to assess bilateral asymmetry. The club head speed correlated positively with the volume of each side of the rectus abdominis and erector spinae, left quadratus lumborum, and the asymmetric ratio of the psoas major (r=0.595-0.747), but negatively with the asymmetric ratio of the quadratus lumborum (r=-0.641). Multiple regression analysis revealed that the right erector spinae volume and the asymmetric ratio of the psoas major were significant contributors for the club head speed (R=0.797). These results indicate that the variation in the club head speed can be strongly explained by the absolute volume and bilateral asymmetry of specific trunk muscles.
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http://dx.doi.org/10.1055/a-1087-2332DOI Listing
June 2020

Bilateral differences in the trunk muscle volume of skilled golfers.

PLoS One 2019 25;14(4):e0214752. Epub 2019 Apr 25.

Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan.

Repetitive mechanical load applied to a body part may lead to hypertrophy of its muscles. If a movement requires asymmetric activation of bilateral muscles, this may result in differences in muscle size between the sides. This study aimed to investigate the degree of bilateral differences in the trunk muscle volume of golfers by comparing with non-golfers. Seventeen male right-handed golfers and eleven (nine right- and two left-handed) non-golfers participated. Trunk muscle volume was determined using magnetic resonance imaging, and the degree of asymmetry was calculated as the ratio of trunk muscle volume on the left to trunk muscle volume on the right side in right-handers and vice-versa in left-handers. Golfers had significantly larger lateral abdominal wall (LA) muscle volume than non-golfers: 12.36 ± 1.12 vs. 9.96 ± 0.94 cm3/kg; erector spinae: 9.12 ± 1.16 vs. 7.88 ± 0.84 cm3/kg; psoas major (PM): 6.27 ± 0.88 vs. 5.51 ± 0.98 cm3/kg; rectus abdominis (RA): 4.15 ± 0.54 vs. 3.50 ± 0.64 cm3/kg; and multifidus: 3.61 ± 0.41 vs. 3.05 ± 0.40 cm3/kg (p < 0.05). The degree of bilateral asymmetry of the LA, PM, and RA volume was significantly greater in golfers than in non-golfers (LA: -8.63 ± 7.40% vs. 1.94 ± 2.76%; PM: -9.10 ± 5.25% vs. -0.48 ± 5.96%; RA: 6.36 ± 6.50% vs. -2.12 ± 9.64%, respectively, p < 0.05). Right-handed golfers had greater left LA and PM volume compared to the right (LA: 5.89 ± 0.55 vs. 6.48 ± 0.65 cm3/kg; PM: 3.00 ± 0.42 vs. 3.27 ± 0.47 cm3/kg; p < 0.05) and had greater right RA volume compared to the left (2.15 ± 0.32 vs. 2.00 ± 0.24 cm3/kg, p < 0.05). These findings suggest that skilled, long-term golfers develop large volume and bilateral asymmetry of their trunk muscles.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0214752PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6483177PMC
December 2019

Validity of block start performance without arm forces or by kinematics-only methods.

Sports Biomech 2019 Jun 16;18(3):229-244. Epub 2019 Apr 16.

a Faculty of Sport and Health Science , Ritsumeikan University , Shiga , Japan.

The purpose of this study was to validate the calculation of reaction time (RT) and normalised power in block starts without considering arm ground reaction forces (GRFs) or using two kinematics-only methods. The RT and normalised power in the action phase were calculated using four different methods: using GRFs of arms and legs by force plates (whole F-based method), which can be regarded as the most valid method, using GRFs of legs captured by force plates (legs F-based method), using position of the centre of mass of the entire body captured by high-speed cameras (whole P-based method), and using only a partial subset of segment position (partial P-based method). Bland-Altman plots demonstrated that the RT of the legs F-based method was not similar to that of the whole F-based method: the mean difference was 7.4 ms and the 95% limits of agreement was-45.1 to 59.8 ms, and it was the least valid method for the calculation among the four methods. In contrast, the normalised power was more valid in the legs F-based method, followed by whole and partial P-based methods. This information will help researchers and practitioners to decide upon their analysis methods when analysing block start performance.
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http://dx.doi.org/10.1080/14763141.2019.1593497DOI Listing
June 2019

Relationship Between Toe Muscular Strength and the Ability to Change Direction in Athletes.

J Hum Kinet 2018 Sep 15;64:47-55. Epub 2018 Oct 15.

Department of Sport and Health Science, Ritsumeikan University, Kusatsu, Japan.

This study aimed to investigate the relationship between toe muscular strength and the ability to change direction in athletes. Seventeen collegiate American-football players participated in the study (age 19.9 ± 0.9 years, competition experience 7.3 ± 1.7 years). Two types of measurements were performed to evaluate toe muscular strength: toe flexor strength with the metatarsophalangeal joint in the planter flexed position and toe-pushing force with the metatarsophalangeal joint in the dorsiflexed position. The ability to change direction was evaluated using the pro-agility and 3-cone tests and change of direction deficits, calculated by subtracting the sprint times from the pro-agility and 3-cone times. There were significant correlations between toe-pushing force and the results of the pro-agility and 3-cone tests, but no significant correlations between toe flexor strength and the pro-agility and 3-cone tests. Neither toe-pushing force nor toe flexor strength was significantly correlated with the sprint test results. Furthermore, toe-pushing force was significantly correlated with the 3-cone test deficit, but toe flexor strength was not. The ability to change direction is more strongly affected by toe muscular strength (measured as toe-pushing force) with the metatarsophalangeal joint in the dorsiflexed angle than by toe muscular strength (measured as toe flexor strength) with the metatarsophalangeal joint in the plantar flexed angle. Our results suggest that athletes can improve their ability to change direction with toe muscular strength training with the metatarsophalangeal joint in the dorsiflexed position.
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http://dx.doi.org/10.1515/hukin-2017-0183DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6231329PMC
September 2018

Chapter 3 Prevention of sarcopenia.

Geriatr Gerontol Int 2018 May;18 Suppl 1:23-27

National Center for Geriatrics and Gerontology, Obu, Japan.

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http://dx.doi.org/10.1111/ggi.13321DOI Listing
May 2018

Non-linear growth trends of toe flexor muscle strength among children, adolescents, and young adults: a cross-sectional study.

Eur J Appl Physiol 2018 May 3;118(5):1003-1010. Epub 2018 Mar 3.

Department of Sport Education, Hokkaido University of Education, Iwamizawa, Hokkaido, Japan.

Purpose: There are only a few studies on the muscular strength of the foot in children and adolescents; thus, the developmental pattern and normative data of these populations during growth are unclear. We sought to elucidate the developmental pattern of the foot muscle strength among children, adolescents, and young adults compared with that of the hand.

Methods: A total of 747 children, adolescents, and young adults participated in this study, and their maximum isometric toe flexor strength (TFS), hand grip strength (HGS), and foot length were measured.

Results: TFS was correlated with HGS (r = 0.785), age (r = 0.659), height (r = 0.757), body mass (r = 0.737), and foot length (r = 0.594). Multiple regression analyses revealed that TFS was correlated with age (β = 0.243 in boys; β = 0.461 in girls), squared value of age (age; β = - 0.296 in boys; β = - 0.260 in girls), and body mass (β = 0.256 in boys; β = 0.311 in girls) in both sexes, indicating a non-linear relationship between age and TFS development. In a regression model for HGS, age was a significant variable, but not age. HGS increased linearly from childhood until young adulthood, whereas TFS increased from childhood until adolescence and then levelled off.

Conclusion: Our results demonstrate that TFS has a different developmental pattern compared with HGS.
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http://dx.doi.org/10.1007/s00421-018-3827-xDOI Listing
May 2018

Relationship between Dietary Protein or Essential Amino Acid Intake and Training-Induced Muscle Hypertrophy among Older Individuals.

J Nutr Sci Vitaminol (Tokyo) 2017 ;63(6):379-388

Graduate School of Sport and Health Science, Ritsumeikan University.

Dietary protein intake is critical for maintaining an optimal muscle mass, especially among older individuals. Although protein supplementation during resistance training (RT) has been shown to further augment training-induced muscle mass in older individuals, the impact of daily variations in protein intake on training-induced muscle mass has not been explored thus far. Therefore, this study aimed to investigate the relationship between the dietary protein and amino acid intake and RT-induced muscle hypertrophy among older individuals. Ten healthy older men (n=10; mean age=69±2 y; body weight (BW)=61.5±2.2 kg; height=1.65±0.02 m) participated in progressive RT performed 3 times/wk for 12 wk. Body composition (using DXA) and nutritional assessments (using a 3-d dietary record) were performed before and after the training period. Leg lean mass (LLM) increased significantly (15.0±0.8 vs. 15.4±0.8 kg, p<0.05) after RT, with no change in dietary nutrient intake. The average dietary protein intake was 1.62±0.11 g/kg BW/d, while essential amino acids was 600±51 mg/kg BW/d. Although the correlation between the increase in LLM and dietary protein intake was not significant, a significant correlation was found between the increase in LLM and dietary essential amino acid (EAA) intake. Furthermore, there were significant correlations between the increase in LLM and protein as well as EAA (especially leucine) intake at breakfast among subjects with suboptimal protein intake (p<0.05). Our study findings indicate that dietary protein as well as EAA intake may be significant contributing factors in muscle hypertrophic response during RT among healthy older men.
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http://dx.doi.org/10.3177/jnsv.63.379DOI Listing
August 2018

Bilateral deficit of spring-like behaviour during hopping in sprinters.

Eur J Appl Physiol 2018 Feb 20;118(2):475-481. Epub 2017 Dec 20.

Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan.

Purpose: Unilateral leg stiffness is a key contributor to sprint running speed, thereby great bilateral deficit (BLD) of leg stiffness would be expected to be observed in sprinters. However, it remains clear only BLD of leg stiffness at the preferred hopping frequency in non-sprinters. The purpose of this study was to clarify the BLD of spring-like behaviour in hopping at various frequencies and the effect of chronic adaptation via sprint running experience on BLD during the hopping.

Methods: Fifteen male experienced sprinters and 12 male novices participated in this study. They were instructed to hop in place at three frequencies (2.0, 2.5, and 3.0 Hz), and to perform hopping with maximal effort. Ground reaction forces (GRF) of both legs during the hopping were recorded using two force plates.

Results: At higher hopping frequencies during the unilateral and bilateral hopping, smaller peak value of vertical GRF (F ) and greater leg stiffness (K ) were significantly observed. The BLD index of F and the BLD index of K were significantly smaller at higher hopping frequencies. No significant differences of BLD index of F and BLD index of K were observed between sprinters and novices.

Conclusion: Our results demonstrate that neuromuscular inhibition in the contralateral leg changes during the hopping based on hopping frequency. This suggests that plyometric training in the beginning of rehabilitation should involve bilateral jumping at a high frequency. In experienced sprinters, detailed mechanics of chronic neuromuscular adaptation via unilateral facilitation of spring-like behaviour should be assessed by measuring electromyographic activity.
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http://dx.doi.org/10.1007/s00421-017-3791-xDOI Listing
February 2018

The Effect of Ongoing Vitamin D and Low-Fat Milk Intake on Bone Metabolism in Female High-School Endurance Runners.

J Clin Med Res 2018 Jan 1;10(1):13-21. Epub 2017 Dec 1.

Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan.

Background: Vitamin D and calcium are essential nutrients for bone health. In addition, vitamin D suppresses inflammatory cytokines and increases bone resorption. Therefore, improvements in bone health by calcium and vitamin D supplementation have the potential to not only improve calcium metabolism but also suppress inflammation associated with exercise training. The purpose of this study was to determine whether ongoing vitamin D supplementation and low-fat milk intake by female high-school endurance runners would improve bone metabolism by suppressing inflammatory cytokines and the parathyroid hormone (PTH).

Methods: Twenty female high-school runners were assigned to a vitamin D supplement and low-fat milk intake group (MKD) or a control group (CON). Participants in the MKD group consumed a vitamin D supplement (1,000 IU/day) and low-fat milk (Ca 315 mg/day) for 6 months. Bone mineral density measurements, blood samples, and questionnaires (regarding menses and diet) were carried out. The UMIN Clinical Trials Registry number is UMIN000027854.

Results: The 25-hydroxyvitamin D (25(OH)D) concentration in MKD was sustained and PTH concentration was decreased regardless of the state of menses. The correlation coefficients of 25(OH)D or PTH concentrations and bone metabolism markers were analyzed by partial correlation coefficient via adjusting the model for frequency of menses. CTX and 25(OH)D concentration were significantly and inversely correlated at baseline (r = -0.61, P < 0.01), 3 months (r = -0.54, P = 0.02), and 6 months (r = -0.53, P = 0.02). CTX and PTH were significantly and positively correlated at 3 months (r = 0.63, P < 0.01) and 6 months (r = 0.52, P = 0.02). The bone alkaline phosphatase (BAP)/CTX ratio and 25(OH)D concentration were significantly and positively correlated at 3 months (r = 0.59, P = 0.01) and 6 months (r = 0.56, P = 0.01). The BAP/CTX ratio and PTH were significantly and inversely correlated at 3 months (r = -0.59, P = 0.01) and 6 months (r = -0.58, P < 0.01).

Conclusions: This study suggested that vitamin D and low-fat milk supplementation improves bone metabolism by sustaining the 25(OH)D concentration and decreasing the PTH concentration in female high-school endurance runners regardless of the state of menses.
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http://dx.doi.org/10.14740/jocmr3209wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5722040PMC
January 2018

Mouth rinsing with a carbohydrate solution attenuates exercise-induced decline in executive function.

J Int Soc Sports Nutr 2017 22;14:45. Epub 2017 Nov 22.

Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga Japan.

Background: A decline in executive function could have a negative influence on the control of actions in dynamic situations, such as sports activities. Mouth rinsing with a carbohydrate solution could serve as an effective treatment for preserving the executive function in exercise. The purpose of this study was to examine the effects of mouth rinsing with a carbohydrate solution on executive function after sustained moderately high-intensity exercise.

Methods: Eight young healthy participants completed 65 min of running at 75% V̇Omax with two mouth-rinsing conditions: with a carbohydrate solution (CHO) or with water (CON). Executive function was assessed before and after exercise by using the incongruent task of the Stroop Color and Word Test. The levels of blood glucose; and plasma adrenocorticotropic hormone (ACTH), epinephrine, and norepinephrine (NE) were evaluated. A two-way repeated-measures ANOVA, with condition (CHO and CON) and time (pre-exercise and post-exercise) as factors, was used to examine the main and interaction effects on the outcome measures.

Results: The reaction time in the incongruent condition of the Stroop test significantly increased after exercise in CON (pre-exercise 529 ± 45 ms vs. post-exercise 547 ± 60 ms,  = 0.029) but not in CHO (pre-exercise 531 ± 54 ms vs. post-exercise 522 ± 80 ms), which resulted in a significant interaction (condition × time) on the reaction time ( = 0.028). The increased reaction time in CON indicates a decline in the executive function, which was attenuated in CHO. Increases in plasma epinephrine and NE levels demonstrated a trend toward attenuation accompanying CHO ( < 0.085), which appeared to be associated with the preservation of executive function. The blood glucose concentration showed neither significant interactions nor main effects of condition.

Conclusions: These findings indicate that mouth rinsing with a carbohydrate solution attenuated the decline in executive function induced by sustained moderately high-intensity exercise, and that such attenuation seems to be unrelated to carbohydrate metabolic pathway but rather attributed, in part, to the inhibition of the excessive release of stress hormones.
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http://dx.doi.org/10.1186/s12970-017-0200-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5700683PMC
March 2018

Aerobic exercise training-induced changes in serum C1q/TNF-related protein levels are associated with reduced arterial stiffness in middle-aged and older adults.

Am J Physiol Regul Integr Comp Physiol 2018 01 25;314(1):R94-R101. Epub 2017 Oct 25.

Faculty of Sport and Health Science, Ritsumeikan University , Shiga , Japan.

Adiponectin regulates endothelial nitric oxide synthase in endothelial cells, and body fat loss by aerobic exercise training promotes adiponectin secretion. Recently, C1q/tumor necrosis factor-related proteins (CTRPs) have been identified as novel adipokines and are paralogs of adiponectin, but the association between exercise training-induced reduction of arterial stiffness and circulating CTRPs levels remains unclear. This study aimed to clarify whether the reduction of arterial stiffness in middle-aged and older adults is associated with the change in serum levels of CTRPs induced by exercise training. A total of 52 middle-aged and older participants were randomly divided into two groups: a training group ( n = 26) and a sedentary control group ( n = 26). Participants in the training group completed 8 wk of aerobic exercise training (60-70% peak oxygen uptake for 45 min, 3 days/wk). The reduction of percent whole body fat, abdominal visceral fat area, and carotid-femoral pulse-wave velocity (cfPWV) was significantly greater in the training group than in the control group ( P < 0.05). Moreover, the increase in serum adiponectin, CTRP3, and CTRP5 from baseline to 8 wk was significantly higher in the training group compared with the control group ( P < 0.05). Additionally, the training-induced change in cfPWV was negatively correlated with the training-induced change in serum adiponectin, CTRP3, and CTRP5 levels ( r = -0.51, r = -0.48, r = -0.42, respectively, P < 0.05), and increased plasma nitrite/nitrate level by exercise training was correlated only with adiponectin levels ( r = 0.41, P < 0.05). These results suggest that the exercise training-induced increase in serum CTRPs levels may be associated with the reduction of arterial stiffness in middle-aged and older adults.
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http://dx.doi.org/10.1152/ajpregu.00212.2017DOI Listing
January 2018

Timing of Gun Fire Influences Sprinters' Multiple Joint Reaction Times of Whole Body in Block Start.

Front Psychol 2017 18;8:810. Epub 2017 May 18.

Faculty of Sport and Health Science, Ritsumeikan UniversityKusatsu, Japan.

Experienced sprinters are specifically adapted to pre-planning an advanced motor program. Herein, sprinters are able to immediately accelerate their center of mass forward with a whole-body coordinated motion, following a steady state crouched position. We examined the effect of variable timing of reaction signals on multiple joint reaction times (RT) and whole-body RT for specialist sprinters. Twenty well-experienced male sprinters performed five start-dashes from a block start under five variable foreperiod (FP) length conditions (1.465, 1.622, 1.780, 1.938, and 2.096 s), with trials randomly timed between a warning and an imperative tone. Participants' sprinting motion and ground reaction forces of their four limbs during the block start were measured simultaneously. Whole-body RT was significantly shorter when FP length was longer; the values of whole-body RT were 117 ± 5 ms, 129 ± 5 ms, 125 ± 4 ms, 133 ± 6 ms, and 156 ± 8 ms in the 2.096, 1.938, 1.780, 1.622, and 1.465-s FP-length conditions, respectively. A repeated-measures analysis of variance found a significant joint-by-FP length interaction in joint-moment RT. These findings suggest that FP length affects coordinated motion in four limbs and whole-body RT. This information will be able to lead to new methods for start signals in sprint running events and advance our understanding of the association between FP length and dynamic coordinated motion.
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http://dx.doi.org/10.3389/fpsyg.2017.00810DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5435752PMC
May 2017

The effects of low-repetition and light-load power training on bone mineral density in postmenopausal women with sarcopenia: a pilot study.

BMC Geriatr 2017 05 2;17(1):102. Epub 2017 May 2.

College of Sport and Health Science, Ritsumeikan University, Shiga, Japan.

Background: Age-related reduction in bone mineral density (BMD) is generally accelerated in women after menopause, and could be even more pronounced in individuals with sarcopenia. Light-load power training with a low number of repetitions would increase BMD, significantly reducing bone loss in individuals at risk of osteoporosis. This study investigated the effects of low-repetition, light-load power training on BMD in Japanese postmenopausal women with sarcopenia.

Methods: The training group (n = 7) followed a progressive power training protocol that increased the load with a weighted vest, for two sessions per week, over the course of 6 weeks. The training exercise comprised five kinds of exercises (squats, front lunges, side lunges, calf raises, and toe raises), and each exercise contained eight sets of three repetitions with a 15-s rest between each set. The control group (n = 8) did not undergo any training intervention. We measured BMD, muscle strength, and anthropometric data.

Results: Within-group changes in pelvis BMD and knee extensor strength were significantly greater in the training group than the control group (p = 0.029 and 0.030 for pelvis BMD and knee extensor strength, respectively). After low-repetition, light-load power training, we noted improvements in pelvis BMD (1.6%) and knee extensor strength (15.5%). No significant within- or between-group differences were observed for anthropometric data or forearm BMD.

Conclusions: Six weeks of low-repetition, light-load power training improved pelvis BMD and knee extensor strength in postmenopausal women with sarcopenia. Since this training program does not require high-load exercise and is therefore easily implementable as daily exercise, it could be an effective form of exercise for sedentary adults at risk for osteoporosis who are fearful of heavy loads and/or training that could cause fatigue.

Trial Registration: This trial was registered with the University Hospital Medical Information Network on 31 October 2016 ( UMIN000024651 ).
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http://dx.doi.org/10.1186/s12877-017-0490-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5414134PMC
May 2017

Impact of Six Consecutive Days of Sprint Training in Hypoxia on Performance in Competitive Sprint Runners.

J Strength Cond Res 2019 Jan;33(1):36-43

Graduate School of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan.

Kasai, N, Mizuno, S, Ishimoto, S, Sakamoto, E, Maruta, M, Kurihara, T, Kurosawa, Y, and Goto, K. Impact of six consecutive days of sprint training in hypoxia on performance in competitive sprint runners. J Strength Cond Res 33(1): 36-43, 2019-The purpose of this study was to determine the effects of 6 successive days of repeated sprint (RS) training in moderate hypoxia on anaerobic capacity in 100-200-m sprint runners. Eighteen male sprint runners (age, 20.0 ± 0.3 years; height, 175.9 ± 1.1 cm; and body mass, 65.0 ± 1.2 kg) performed repeated cycling sprints for 6 consecutive days in either normoxic (NOR; fraction of inspired oxygen [FiO2], 20.9%; n = 9) or hypoxic conditions (HYPO; FiO2, 14.5%; n = 9). The RS ability (10 × 6-second sprints), 30-second maximal sprint ability, maximal oxygen uptake ((Equation is included in full-text article.)max), and 60-m running time on the track were measured before and after the training period. Intramuscular phosphocreatine (PCr) content (quadriceps femoris muscle) was measured by P-magnetic resonance spectroscopy (P-MRS) before and after the training period. Both groups showed similar improvements in RS ability after the training period (p < 0.05). Power output during the 30-second maximal sprint test and (Equation is included in full-text article.)max did not change significantly after the training period in either group. Running time for 0-10 m improved significantly after the training period in the HYPO only (before, 1.39 ± 0.01 seconds; after, 1.34 ± 0.02 seconds, p < 0.05). The HYPO also showed a significant increase in intramuscular PCr content after the training period (before, 31.5 ± 1.3 mM; after, 38.2 ± 2.8 mM, p < 0.05). These results suggest that sprint training for 6 consecutive days in hypoxia or normoxia improved RS ability in competitive sprint runners.
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http://dx.doi.org/10.1519/JSC.0000000000001954DOI Listing
January 2019

Association between aerobic exercise training effects of serum adropin level, arterial stiffness, and adiposity in obese elderly adults.

Appl Physiol Nutr Metab 2017 Jan 13;42(1):8-14. Epub 2016 Sep 13.

a Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan.

Serum levels of adropin, which enhances endothelial cell release of nitric oxide (NO), are lower in obese patients. Although habitual aerobic exercise reduces arterial stiffness and adiposity, the relationship between these effects and circulating levels of adropin remains unclear. The purpose of this study was to determine if serum adropin level is associated with the effects of aerobic exercise training on arterial stiffness and adiposity in obese adults. In Experiment 1, we examined whether serum adropin levels are associated with cardiorespiratory fitness, carotid β-stiffness, plasma nitrite/nitrate (NOx) level, and abdominal visceral fat in 27 normal, 20 overweight, and 25 obese adults (age, 41-79 years). In Experiment 2, we examined the effects of an 8-week aerobic exercise training program on the relationship between serum adropin level and arterial stiffness or adiposity in 13 obese adults (age, 54-76 years). Serum adropin levels in normal, overweight, and obese adults negatively correlated with carotid β-stiffness and abdominal visceral fat, and positively correlated with plasma NOx level and cardiorespiratory fitness. After the 8-week exercise program, serum adropin levels in obese adults were elevated, and correlated with training-induced changes in carotid β-stiffness (r = -0.573, P < 0.05), plasma NOx level (r = 0.671, P < 0.05), and abdominal visceral fat (r = -0.585, P < 0.05). These findings suggest that the exercise training-induced increase in serum adropin may be related to the training effects of arterial stiffness and adiposity in obese adults.
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http://dx.doi.org/10.1139/apnm-2016-0310DOI Listing
January 2017

New ultrasonography-based method for predicting total skeletal muscle mass in male athletes.

J Phys Ther Sci 2016 May 31;28(5):1556-9. Epub 2016 May 31.

Graduate School of Sport and Health Science, Ritsumeikan University, Japan.

[Purpose] This study aimed 1) to assess whether a prediction model for whole body skeletal muscle mass that is based on a sedentary population is applicable to young male athletes, and 2) to develop a new skeletal muscle mass prediction model for young male athletes. [Subjects and Methods] The skeletal muscle mass of 61 male athletes was measured using magnetic resonance imaging (MRI) and estimated using a previous prediction model (Sanada et al., 2006) with B-mode ultrasonography. The prediction model was not suitable for young male athletes, as a significant difference was observed between the means of the estimated and MRI-measured skeletal muscle mass. Next, the same subjects were randomly assigned to a development or validation group, and a new model specifically relevant to young male athletes was developed based on MRI and ultrasound data obtained from the development group. [Results] A strong correlation was observed between the skeletal muscle mass estimated by the new model and the MRI-measured skeletal muscle mass (r=0.96) in the validation group, without significant difference between their means. No bias was found in the new model using Bland-Altman analysis (r=-0.25). [Conclusion] These results validate the new model and suggest that ultrasonography is a reliable method for measuring skeletal muscle mass in young male athletes.
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http://dx.doi.org/10.1589/jpts.28.1556DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4905909PMC
May 2016

Relationship between lateral differences in the cross-sectional area of the psoas muscle and curve running time.

J Physiol Anthropol 2016 Jan 26;35. Epub 2016 Jan 26.

Department of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan.

Background: The aim of this study was to investigate whether lateral differences in the cross-sectional areas of the hip and thigh muscles were related to curve sprinting time.

Methods: Thirteen college students (10 men and 3 women; mean ± SD: age, 20.4 ± 1.7 years; height, 167.6 ± 8.9 cm; mass, 57.4 ± 5.4 kg) participated in this study. The participants were instructed to sprint along a circular track (23 m radius) in the counterclockwise and clockwise directions. Magnetic resonance imaging was used to measure the cross-sectional area of the psoas major, quadriceps femoris, and hamstring muscles. The symmetry index was used to evaluate the lateral differences in the cross-sectional area.

Results: The lateral difference was observed in the cross-sectional area (CSA) of the thigh muscles, not in the psoas major muscle. The sprint time was not significantly different between the counterclockwise (22.15 ± 2.27 s) and clockwise (22.13 ± 2.32 s) directions. No significant correlations were found between the symmetry index of the thigh muscles and the cross-directional differences in sprint time. However, the symmetry index of the psoas major muscle correlated significantly with the cross-directional difference in sprint time (r = -0.614, P = 0.026).

Conclusions: These findings suggest that the participants in whom the cross-sectional area of the psoas major muscle of the outer leg was larger than that of the inner leg were faster in curve sprinting.
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http://dx.doi.org/10.1186/s40101-016-0086-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4727261PMC
January 2016

Ultrasound-Derived Abdominal Muscle Thickness Better Detects Metabolic Syndrome Risk in Obese Patients than Skeletal Muscle Index Measured by Dual-Energy X-Ray Absorptiometry.

PLoS One 2015 23;10(12):e0143858. Epub 2015 Dec 23.

College of Sport and Health Science, Ritsumeikan University, Shiga, Japan.

Sarcopenia has never been diagnosed based on site-specific muscle loss, and little is known about the relationship between site-specific muscle loss and metabolic syndrome (MetS) risk factors. To this end, this cross-sectional study aimed to investigate the relationship between site-specific muscle size and MetS risk factors. Subjects were 38 obese men and women aged 40-82 years. Total body fat and lean body mass were assessed by whole-body dual-energy X-ray absorptiometry (DXA) scan. Muscle thickness (MTH) was measured using B-mode ultrasound scanning in six body regions. Subjects were classified into general obesity (GO) and sarcopenic obesity (SO) groups using the threshold values of one standard deviation below the sex-specific means of either MTH or skeletal muscle index (SMI) measured by DXA. MetS risk score was acquired by standardizing and summing the following continuously distributed variables: visceral fat area, mean blood pressure, HbA1c, and serum triglyceride / high density lipoprotein cholesterol, to obtain the Z-score. Multiple regression analysis revealed that the MetS risk score was independently associated with abdominal MTH in all subjects, but not with MTH in other muscle regions, including the thigh. Although HbA1c and the number of MetS risk factors in the SO group were significantly higher than those in the GO group, there were no significant differences between GO and SO groups as defined by SMI. Ultrasound-derived abdominal MTH would allow a better assessment of sarcopenia in obese patients and can be used as an alternative to the conventionally-used SMI measured by DXA.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0143858PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4689364PMC
July 2016

Effect of a Wide Stance on Block Start Performance in Sprint Running.

PLoS One 2015 6;10(11):e0142230. Epub 2015 Nov 6.

Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan.

This study aimed to clarify the effect of widened stance width at the set position during the block start phase in sprint running on kinematics and kinetics at the hip joint and block-induced power. Fourteen male sprinters volunteered to participate in this study. They performed three block-start trials with a normal stance width (25 ± 1 cm, normal condition) and a widened stance width (45 ± 2 cm, widened condition) at the set position. The block start movements were recorded at 250 Hz with high-speed cameras and the ground reaction forces at 1250 Hz with force plates. During the block phase in the widened condition, the hip abduction and external rotation angles in both legs were significantly larger and smaller, respectively, than those in the normal condition. The positive peak value of the hip power in the rear leg was significantly greater in the widened condition than that in the normal condition. However, no significant difference was seen in the normalized block-induced power between the widened and normal conditions. We conclude that a widened stance width at the set position affects the hip-joint kinematics and rear hip power generation during the block start phase, but no effect on the block-induced power when considering sprinting performance during the whole block start phase.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0142230PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4636312PMC
June 2016

Toe Flexor Strength, Flexibility and Function and Flexor Hallucis Longus Tendon Morphology in Dancers and Non-Dancers.

Med Probl Perform Art 2015 09;30(3):152-6

Division of Biokinesiology and Physical Therapy, University of Southern California, 1540 East Alcazar Street, CHP-155, Los Angeles, CA 90089, USA. Tel 323-442-2911, fax 323-442-1515.

Tendinopathy of the flexor hallucis longus (FHL), colloquially referred to as "dancer's tendinitis," is a common condition in dancers and attributed to high demand on this muscle in positions of extreme ankle plantarflexion and metatarsophalangeal (MTP)) flexion and extension. Despite such a high prevalence, there has been little research into preventative or nonsurgical interventions. As a means to identify potential targets for prevention and intervention, this study aimed to characterize toe flexors in dancers by measuring strength, flexibility, function, and FHL tendon morphology. Dancers (n=25) were compared to non-dancers (n=25) in toe flexor isometric strength, first MTP joint range of motion, foot longitudinal arch flexibility, balance ability, endurance during modified heel raises without use of the toes, and FHL tendon thickness, cross-sectional area, and peak spatial frequency. Significant differences were found in functional first MTP joint extension (dancers 101.95°, non-dancers 91.15°, p<0.001), balance ability during single-leg stance on the toes (dancers 11.43 s, non-dancers 5.90 s, p=0.013), and during modified heel raises (dancers 22.20 reps, non-dancers 28.80 reps, p=0.001). Findings indicate that dancers rely on toe flexors more than non-dancers to complete balance and heel raise tasks. Efficacy of using this modified heel raise task with the toes off the edge of a block as a means to train larger plantarflexors and as a nonsurgical intervention should be studied in the future. Improving interventions for FHL tendinopathy will be impactful for dancers, in whom this condition is highly prevalent.
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http://dx.doi.org/10.21091/mppa.2015.3029DOI Listing
September 2015

A 3-day high-fat/low-carbohydrate diet does not alter exercise-induced growth hormone response in healthy males.

Growth Horm IGF Res 2015 Dec 10;25(6):304-11. Epub 2015 Sep 10.

Graduate School of Sport and Health Science, Ritsumeikan University, Shiga, Japan; Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan. Electronic address:

Objective: The purpose of the present study was to examine the effects of 3 days isoenergetic high-fat/low-carbohydrate diet (HF-LC) relative to low-fat/high-carbohydrate diet (LF-HC) on the exercise-induced growth hormone (GH) response in healthy male subjects.

Design: Ten healthy young males participated in this study. Each subject consumed the HF-LC (18±1% protein, 61±2% fat, 21±1% carbohydrate, 2720 kcal per day) for 3 consecutive days after consuming the LF-HC (18±1% protein, 20±1% fat, 62±1% carbohydrate, 2755 kcal per day) for 3 consecutive days. After each dietary intervention period, the hormonal and metabolic responses to an acute exercise (30 min of continuous pedaling at 60% of V˙O2max) were compared. The intramyocellular lipid (IMCL) contents in the vastus lateralis, soleus, and tibialis anterior were evaluated by proton magnetic resonance spectroscopy.

Results: Serum GH concentrations increased significantly during the exercise after both the HF-LC and LF-HC periods (P<0.05). However, the exercise-induced GH response was not significantly different between the two periods. Fat utilization and lipolytic responses during the exercise were enhanced significantly after the HF-LC period compared with the LF-HC period. IMCL content did not differ significantly in any portion of muscle after the dietary interventions.

Conclusions: We could not show that short-term HF-LC consumption changed significantly exercise-induced GH response or IMCL content in healthy young males.
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http://dx.doi.org/10.1016/j.ghir.2015.07.005DOI Listing
December 2015

Specific characterization of regional storage fat in upper and lower limbs of young healthy adults.

Springerplus 2015 8;4:402. Epub 2015 Aug 8.

Future Institute for Sport Sciences, Tokyo, Japan.

This study aimed to determine the specific characterization of regional storage fat in the upper limb as compared to the lower limb of young healthy adults. The regional storage fat and skeletal muscle in upper and lower limbs were obtained by magnetic resonance imaging (MRI) and multifrequency bioelectrical impedance analysis (BIA). For MRI measurements, images at the continuous anatomical cross-sectional areas of subcutaneous adipose tissue and skeletal muscle in the upper arm and thigh were selected for the analysis. Values measured by MRI were larger than those measured by BIA. MRI data showed that the percentage of fat was significantly higher in the upper arm compared to the thigh in both men and women. This study suggests that BIA results in a significantly different estimation of the whole body and limb composition when compared to MRI and that MRI is useful to determine regional specificities in the limb composition. From these quantified evaluation, we found significantly large amount of regional storage fat in upper limbs of young healthy adults, especially women.
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http://dx.doi.org/10.1186/s40064-015-1181-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4529424PMC
August 2015

Comparison of the muscle fascicle length between resistance-trained and untrained individuals: cross-sectional observation.

Springerplus 2015 11;4:341. Epub 2015 Jul 11.

Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1, Noji-higashi, Kusatsu, Shiga 525-8577 Japan.

Background: Muscle plasticity is an important topic in the fields of sport science and physical therapy. The purpose of this study was to examine whether muscle fascicle length increases with resistance training through a comparison between resistance-trained and untrained individuals. If a hypothesis that fascicle length increases by resistance training is true, fascicle length should be longer in the resistance-trained individuals than in the untrained individuals.

Findings: Sixteen individuals (age, 21.3 ± 3.3 years; height, 1.74 ± 0.05 m; body mass, 83.6 ± 9.0 kg), who were either body builders or rugby players, were recruited as the training group, and 11 individuals (age, 20.3 ± 2.1 years; height, 1.70 ± 0.06 m; body mass, 54.0 ± 4.7 kg), who did not have regular resistance training experiences, were recruited as the control group. Fascicle length, pennation angle, and muscle thickness of the vastus lateralis and medial gastrocnemius were measured from ultrasonographic images. We found that the muscle thickness and pennation angles in the training group were significantly larger than those in the control group (p < 0.05). However, fascicle length did not significantly differ between the two groups (p > 0.05).

Conclusions: These results indicate that fascicle length is not associated with muscle size, suggesting that fascicle length would not increase with resistance training.
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http://dx.doi.org/10.1186/s40064-015-1133-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4499036PMC
July 2015

Intramuscular water movement during and after isometric muscle contraction: evaluation at different exercise intensities.

Clin Physiol Funct Imaging 2016 Sep 3;36(5):368-75. Epub 2015 Jul 3.

Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Japan.

We aimed at evaluating the effect of isometric muscle contraction on intramuscular water movement at different exercise intensities. Seven men performed 1-min isometric ankle dorsiflexion (20% and 50% maximal voluntary contractions [MVCs]) with a non-magnetic custom-made dynamometer, inside a magnetic resonance (MR) device. Axial diffusion-weighted images were obtained before, during and at 1-20 min (1-min interval) after the exercise to calculate the apparent diffusion coefficient (ADC) of the tibialis anterior. Under the same exercise condition, the concentration change of total haemoglobin (Hb) and myoglobin (Mb) (total Hb/Mb) within the tibialis anterior was assessed by performing near-infrared spectroscopy before, during and after the exercise outside the MR device. The 20% MVC exercise significantly increased the ADC only at 1 min postexercise (P<0·01), whereas the ADC significantly increased during and at 2-20 min after the 50% MVC exercise (P<0·01). The 20% MVC exercise decreased the total Hb/Mb during exercise (P<0·01), but the value significantly increased at 1 min postexercise (P<0·01). The total Hb/Mb significantly decreased during the 50% MVC exercise, but significantly increased at 1-5 min postexercise (P<0·01). One-minute moderate-intensity isometric exercise activates intramuscular water movement during and after the exercise. This activation was found even after a low-intensity exercise, but the effect was small and did not last long. The effect of intramuscular hyperaemia on the postexercise ADC elevation may be limited to the very early period after low- to moderate-intensity exercises.
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http://dx.doi.org/10.1111/cpf.12239DOI Listing
September 2016
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