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Volume 61, Issue 1
Displaying 51-61 of 61 articles from this issue
Original
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Takaya Yoshimoto, Yohei Takai, Eiji Fujita, Yuko Fukunaga, Hirofumi Ki ...2012 Volume 61 Issue 1 Pages 79-88
Published: 2012
Released on J-STAGE: March 14, 2012
JOURNAL FREE ACCESSThis study aimed to determine the relationships between the torque generating capacity of the lower extremity muscles and either running or jump performance in primary and junior high school boys. A total of 102 primary and junior high school boys participated in this study. Muscle thicknesses (MTs) of the knee extensors and plantar flexors were determined using ultrasonography. Muscle volumes (MVs) of the knee extensors and plantar flexors were estimated using MTs and limb lengths. The isometric joint torques (TQs) for knee extensors and ankle plantar flexors were measured using myometer. MV and TQ were divided by body mass (MV/BM and TQ/BM, respectively). Running velocity was measured using a non-motorized treadmill. The counter movement jump (CMJ) and squat jump (SJ) were performed on a matswitch system. The flight time was measured and used to calculate the heights of CMJ and SJ using the following equation; height (cm) = g × (flight time)2 /8/10. As the result of multiple regression analysis, age, MV/BM and TQ/BM were selected as predictors of running velocity in the primary school boys, whereas TQ and lean body mass in junior high school boys. In the primary school boys, TQ/BM and body fat mass was selected as significant contributors for SJ and CMJ performances, whereas, in the junior high school boys, TQ and the percent of body fat for SJ performance and MV/BM and TQ for CMJ performance. Thus, the present results indicate that the relationships between torque generating capacity of the lower extremity muscles and either running or jump performance differ between primary and junior high school boys. It may be assumed that, for running and jump performances, muscle mass and strength become determinant factors in junior high school boys, whereas their values relative to body mass in primary school boys.View full abstractDownload PDF (1172K) -
Kazuaki Hamada, Yukio Urabe, Yuki Yamanaka2012 Volume 61 Issue 1 Pages 89-93
Published: 2012
Released on J-STAGE: March 14, 2012
JOURNAL FREE ACCESSThe aim of the present study was to investigate whether personal hamstring muscular activation increased by landing with the trunk bent forward. First, 14 healthy female university students were instructed to perform normal drop landing from a 40 cm-high box on both legs. Second, subjects were directed to perform drop landing with the trunk bent forward. Using images obtained from a high-speed video camera, the upper center of mass was calculated in the sagittal plane for determining the differences in these landings. For 0.1 second after toe contact, the muscular activation of quadriceps femoris and hamstring muscles was analyzed using an electromyogram (EMG), and these findings were compared between the 2 types of landings. There was no significant difference in the activation of quadriceps femoris, but the activation tended to decrease during landing with the trunk bent forward. However, the activation of hamstring muscles increased significantly during landing with the trunk bent forward compared with that during normal landing. During landing with the trunk bent forward, the activation of hamstring muscles increased, and the activation of quadriceps femoris tended to decrease. Because contraction of hamstring muscles decreases tension in the anterior cruciate ligament, the findings of this study may help in the prevention of anterior cruciate ligament (ACL) injury.View full abstractDownload PDF (1212K) -
Akira Nishikawa, Shunsuke Nishio, Akiko Nishikawa, Hidetaka Imagita2012 Volume 61 Issue 1 Pages 95-101
Published: 2012
Released on J-STAGE: March 14, 2012
JOURNAL FREE ACCESSIn the present study, we investigated the effects of fracture fixation on joint contracture and disuse muscle atrophy. We surgically fractured the right hind limbs of male Wistar rats, and then fixed the right ankle joints at maximal plantar flexion for two weeks using dorsal splints. Compared with immobilized healthy and sham operated joints, the fractured joints concomitantly showed highly restricted range of motion and significantly higher degrees of disuse atrophy in soleus muscle; decrease of muscle fiber cross sectional area, development of central core lesion and a change in myosin heavy chain isoforms from slow type myosin to fast type myosin. Therefore, it is suggested that orthopedic fracture fixation induces intense disuse muscle atrophy to aggravate joint contracture.View full abstractDownload PDF (1481K) -
Sang-Joon Park, Yohei Otaka, Shinpei Okada, Hiroharu Kamioka, Hiroyasu ...2012 Volume 61 Issue 1 Pages 103-109
Published: 2012
Released on J-STAGE: March 14, 2012
JOURNAL FREE ACCESSIn this study, we investigated whether subjects with a Lower Maximum Step Length (MSL) Percentage (LMP) display unstable locomotion while negotiating an obstacle. Data were collected using a three-dimensional motion analysis system. The toe-obstacle clearance of the leading limb was monitored in 10 young adults while stepping over three height obstacles from 30%, 40% and 50% of MSL. The vertical clearance at the time of the obstacle crossing decreased systematically with more complicated experimental set up. In particular, subjects with LMP showed smaller clearances than subjects with a Higher Maximum step length Percentage (HMP). Furthermore, a significant correlation was observed between the toe-obstacle clearance and MSL. The mean of variance value of toe-obstacle clearance of the leading limb differed between the subjects with LMP and those with HMP. Our findings help to explain the relation of MSL and gait adaption ability to negotiate obstacles safely during obstacles crossing.View full abstractDownload PDF (1134K) -
Chinatsu Aiba, Baobao Han, Masataka Kiuchi, Daisuke Ando, Mitsuya Yama ...2012 Volume 61 Issue 1 Pages 111-117
Published: 2012
Released on J-STAGE: March 14, 2012
JOURNAL FREE ACCESSThe purpose of this study was to investigate the effect of attenuation of exercise-induced oxidative stress by antioxidant administration on brain-derived neurotrophic factor (BDNF) expression in the rat hippocampus. Wistar rats were assigned to four groups: non-exercise (Cont), exercise (Ex), or the combination of exercise with antioxidant administration (small dose: SP, large dose: LP) group. Exercise groups were subjected to treadmill running for 10 consecutive days. The exercise load increased gradually by 5 m/min per day for the first 5 days (10 m/min-30 m/min), and maintained at 30 m/min for the last 5 days. In addition, SP and LP were injected with N-tert butyl-a-phenyl nitrone (PBN) 1h prior to exercise. High-intensity exercise resulted in increased hippocampal 4-hydroxy-2-nonenal (4-HNE) contents compared with Cont. But this elevation was completely suppressed by a large dose of PBN. In Ex and SP, serum total antioxidative power were significantly decreased compared with Cont, whereas no changes were observed in LP. There was a significant negative correlation between hippocampal 4-HNE contents and serum total antioxidative power in SP and LP, suggesting the hypothesis that exercise-induced reduction in total antioxidant power might lead hippocampal 4-HNE accumulation. Furthermore, there was a significant increase of hippocampal BDNF level in LP compared with Cont and Ex. These findings indicate that an increase of oxidative stress might not have a beneficial effect on hippocampal BDNF expression. Our results of this study also suggest that attenuation of exercise-induced oxidative stress by some antioxidants contributes to BDNF expression in the hippocampus.View full abstractDownload PDF (3712K) -
Makoto Suzukawa, Yasuharu Nagano, Tatsuya Tamaki, Emi Nakamura, Yu Shi ...2012 Volume 61 Issue 1 Pages 119-124
Published: 2012
Released on J-STAGE: March 14, 2012
JOURNAL FREE ACCESSAnterior Cruciate Ligament Injury often occurs as a result of knee valgus collapse during landing or pivoting in sports activity. Previous studies reported that the risk of ACL injuries was reduced by jump and balance training, and those training can be effective as the prevention program for the ACL injuries. But those studies often focused on only adult athletes, and there are few studies focused on junior athletes. The purpose of this study is to investigate the pattern of landing movement in junior athletes, and to verify the effect of the prevention program. One-hundred and ten junior basketball players (boys; 61, girls;49, age ranging 12 to 15) were subjected in this study. We measured the knee flexion, valgus angles and jump height during continuous vertical jump. After measuring, they executed a prevention program for 12 weeks. The motion pattern of the knee during jump test were compaired between before and after prevention program. Female athletes showed greater knee valgus angle at initial landing phase and grater maximum knee valgus angle than those of males. As a result of the prevention program, maximum knee valgus angle was significantly decreased in female athletes. The greater angle of knee valgus in female may increase the risk of ACL injuries. Present study suggests that the prevention program is useful for reducing the risk of ACL injury. Increment of jump height in male players after this program might be considered that this training program has also an effect of performance improvement.View full abstractDownload PDF (1224K) -
Jun Horie, Shin-ichiro Hayashi, Masahide Tanaka, Kunihiko Anami, Etsuo ...2012 Volume 61 Issue 1 Pages 125-130
Published: 2012
Released on J-STAGE: March 14, 2012
JOURNAL FREE ACCESSTo determine the influence of “thin”, “normal”, and “obesity” on the motor function and exercise capacity of chronic obstructive pulmonary disease (COPD) patients, as well as whether “obesity” is actually “harmful” for such patients. A total of 103 COPD patients in a stable condition were classified into three groups: a “thin group” (BMI<18.5), an “normal group” (18.5≤BMI<25), and an “obesity group” (BMI≥25). Fourteen patients from each group matched for %FEV1.0, sex, and age were evaluated. The measurement items were: respiratory function, respiratory muscle strength, lower and upper limb muscle strength, the 30-sec chair-stand test (CS-30), timed up and go test (TUG), 6-minute walking test (6MWT), incremental shuttle walking test (ISWT), Nagasaki university respiratory questionnaire (NRADL), and St. George’s respiratory questionnaire (SGRQ). As a result of comparing the three groups, the %MIP was significantly higher in the obesity compared to thin group (p=0.04). No differences were seen between the groups in the mMRC, %MEP, quadriceps femoris muscle strength (%), CS-30, TUG, 6MWT, ISWT, NRSDL, and SGRQ, but these values showed a tendency to be favorable in the obesity group. The BMI was significantly and positively correlated with the %MIP and NRADL. It was suggested that management of the respiratory muscle strength, exercise tolerance, and ADL when COPD patients are obese rather than thin can be possibly associated with a higher QOL.View full abstractDownload PDF (1713K) -
Kaoru Tsuyama, Asumi Hoshiba, Hiroyuki Nakajima2012 Volume 61 Issue 1 Pages 131-137
Published: 2012
Released on J-STAGE: March 14, 2012
JOURNAL FREE ACCESSThis study examined age-related changes in dynamic balance (DB) ability, and the relationship between DB ability and isometric knee extension strength (IKES). Subjects were 100 females who regularly performed some light gymnastic exercises at a gymnastics club once or twice a week. Subject ages ranged from 20 to 85 years old. The measured items were height, body weight (BW), IKES, and DB ability. Results were as follows: 1. The average DB ability tended to gradually decrease as the subjects got older. There were some significant differences in the average DB ability between the 20 to 29 and 60 to 69 age groups, and between the 20 to 29 and over 70 age groups. 2. It was shown that there was a significant negative correlation between age and DB ability (r=0.471, p<0.001). 3. There was a significant negative correlation between age and IKES/BW (r=0.579, p<0.001). 4. It was shown that there was a significant positive correlation between IKES/BW and DB ability (r=0.368, p<0.001). 5. There was a significant negative correlation between BMI and DB ability (r=0.370, p<0.001). This study showed that DB ability rapidly decreased over 60 years old, and also the value tended to be higher in persons with a higher knee extension strength and lower BMI. Therefore, it was suggested that it is important to increase the knee extension strength and maintain an appropriate BMI in order to maintain DB ability.View full abstractDownload PDF (1198K)
Material
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Kenji Kuzuhara, Junta Iguchi, Masashi Shibata2012 Volume 61 Issue 1 Pages 139-145
Published: 2012
Released on J-STAGE: March 14, 2012
JOURNAL FREE ACCESSCollegiate American football injuries for two year seasons in Japanese Kansai Division I team were analyzed using injury rates (IR) per 1000 athlete-exposures (1000AE: one athlete-exposure was defined as a player participating in one game or one practice.), especially focusing on lower limb injuries. The overall game injury rate (GIR: 38.3) was significantly higher than practice injury rate (PIR: 13.1) (X2=12.355, p < 0.05). The difference between GIR in 2008 season (50.8) and in 2007 season (25.7) was significant (X2=8.235, p < 0.05). The lower extremity injuries approximately occupied 60% of all injuries, especially GIRs of both ankle inversion sprains (3.8) and anterior cruciate ligament (ACL: 3.3) injuries being much higher. PIR in this study was higher than the rates of collegiate American football teams in the U.S.A., especially PIRs of knee ligament injuries (ACL and medial collateral ligament injuries) and ankle sprains (inversion and eversion sprains) being much higher. Regarding the occurrence of injury, GIR with contact in ACL injuries (2.8) and GIR without contact in ankle inversion sprains (2.4) were the highest. It is also necessary to change practice plans and circumstances so that the PIR of knee and ankle injuries could be reduced. Research is needed on injury prevention for knee and ankle injuries in the games and practices.View full abstractDownload PDF (1206K)
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2012 Volume 61 Issue 1 Pages 147-150
Published: 2012
Released on J-STAGE: March 14, 2012
JOURNAL FREE ACCESSDownload PDF (952K) -
2012 Volume 61 Issue 1 Pages 151-155
Published: 2012
Released on J-STAGE: March 14, 2012
JOURNAL FREE ACCESSDownload PDF (971K)