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Volume 56 (2007)
- Issue 6 Pages 579-
- Issue 5 Pages 451-
- Issue 4 Pages 385-
- Issue 3 Pages 315-
- Issue 2 Pages 203-
- Issue 1 Pages 1-
Volume 56, Issue 4
Displaying 1-7 of 7 articles from this issue
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Review
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NOBUYUKI INUI2007 Volume 56 Issue 4 Pages 385-400
Published: August 01, 2007
Released on J-STAGE: September 14, 2007
JOURNAL FREE ACCESSMovement timing and muscle force are two main parameters in motor coordination that differentiate people across a variety of movements. These parameters have been studied separately in the field of human motor control. In the last two decades, however, some studies have been reported on motor timing and its relation to control of force. The present review thus presents independence and interaction of the control of timing and force in both stimulus-initiated and self-paced movements. In a motor task of simple reaction time as a stimulus-initiated movement, although several studies revealed that experimental factors such as signal intensity, signal duration, and foreperiod duration influenced response force as well as reaction time, these studies indicated that the factors affected response force and reaction time differentially. During a self-paced task of periodic finger tapping sequences, the accuracy of controlling muscle force was not correlated with the precision of timing control. In addition, whereas variations in intertap interval were quite accurately controlled across conditions, those in peak force were not. Thus, because force control is largely independent of timing, timing and force may be controlled by different parts of the brain. To the contrary, some studies reported different interdependencies between the two parameters. During a task of tapping sequences with a stress tap, some reports found a lengthening of the intertap interval before and after a stress tap. Positive correlations between intertap interval and peak force were only observed for high tapping frequencies. As an example of dexterous voluntary movements, on the other hand, highly skilled pianists are known to be able to independently control keystroke timing and force in piano playing. Neural circuits underlying the independence and interaction of timing and force control were finally discussed.View full abstractDownload PDF (393K)
Original
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YOSHINORI MIYAZAKI2007 Volume 56 Issue 4 Pages 401-408
Published: August 01, 2007
Released on J-STAGE: September 14, 2007
JOURNAL FREE ACCESSThe purpose of this study was to investigate the landing impacts of falls from short heights with body weight increment. Eight male college students participated as subjects. The body weight increments were gradually increased by 2, 4, 6, 8 and 10 kg by attaching 500 gram iron bars in the pocket of vests that students wore. The subjects performed the landing by falling from a height of 2.7 m above and they landed on the surface of a force plate as softly as possible. The landing impacts, muscular activities, and joint movements of lower limbs during landing were analyzed by a force plate using EMG and VTR programs.
The results indicated that there were no significant increments found in maximal landing impact even though the body weight was increased from 2 to 10 kg. The flexion of ankle, knee and hip joints started immediately before landing and increased after landing with the body weight increments. The activity of plantar and dorsi flexor muscles after landing were increased intensively with the body weight increments. Although the body weight increased from 2 to 10 kg gradually, landing impact at fall did not increase. It may be controlled by fast and deep flexing movements of lower limb joints during landing.View full abstractDownload PDF (214K) -
XIUYING HU2007 Volume 56 Issue 4 Pages 409-418
Published: August 01, 2007
Released on J-STAGE: September 14, 2007
JOURNAL FREE ACCESSBackground : Tai Chi is suitable for most Chinese immigrants, because it is an ancient fitness exercise with Chinese cultural background. Research has suggested that Tai Chi improves functional fitness and reduces stress and anxiety.
Purpose : The purpose of this study was to evaluate the short and long effects of a 3-month Tai Chi exercise program on the functional fitness and subjective health status of older Japanese returnees from China.
Design : Randomized Controlled Trial (RCT).
Method : After obtaining informed consent, 54 participants (63.5±3.7 yrs) were randomly allocated into either an intervention group (n=27) or a control group (n=27). The intervention program included 60-minutes of Tai Chi and a health talk, etc. The program was offered once a week for a 3-month period with home-based Tai Chi performed daily. Interview surveys included items such as demography, self-related health, habits of exercise, history of falls, etc. The participants also underwent evaluations for functional fitness. Data were collected at baseline, 12 weeks, and a 3-month follow-up. A description of the intervention group's impressions about Tai Chi was added at the end of the program. Repeated measures of analysis of variance (ANOVA) and Cochran's Q-test were taken to test for changes in outcome variable.
Results : There were no significant differences in any of the baseline characteristics between the intervention and control groups. At the program completion and 3-month follow-up, the intervention group showed the following : (1) a significantly better performance in functional fitness : time interaction for one leg standing time with eyes opened (P<0.01) and closed (P<0.01), functional reach (P<0.01), tandem walking (P<0.01), Timed Up & Go (P<0.05), and walking speed (P<0.01) ; (2) significantly better improvement in self-rated health (P<0.01), life satisfaction (P<0.01), and concern about own health (P<0.01) ; (3) As to impressions, 85.2% responded “We feel that Tai Chi is an intimate activity in our lives” ; and 63.0% reported “We are attached to Tai Chi, and we do Tai Chi to restore confidence in our health” in the intervention group. By comparison, no significant changes in control group were observed.
Conclusion : These results showed that Tai Chi is effective for functional fitness and subjective health status in older Japanese returnees from China. This study also provides a valuable example of investigating the significance of culturally relevant interventions for Chinese immigrants, especially the aged.View full abstractDownload PDF (230K) -
YUKI KAWATA, KENJI TOGASHI, HIDENARI MASUDA, HIDEAKI SOYA, AKIRA KATSU ...2007 Volume 56 Issue 4 Pages 419-428
Published: August 01, 2007
Released on J-STAGE: September 14, 2007
JOURNAL FREE ACCESSGhrelin, an endogenous ligand for the growth hormone (GH) secretagogue receptor, has been reported to induce a GH-releasing, orexigenic effect on weight gain, and adipogenic actions. It is, therefore, thought that ghrelin links the regulatory systems for growth and energy balance.
We examined 25 obese children undergoing a 3-month inpatient weight reduction program for obese children based on a combination of diet and exercise therapy and evaluated the change in the serum ghrelin levels.
The subjects consisted of 25 children with moderate to severe simple obesity [17 boys, 8 girls ; mean age 9.9±1.3 years, percent overweight (% overweight) 52.1±13.6%]. Height, weight, percent body fat (% BF), fat mass, fat-free mass (FFM), and serum ghrelin were measured before and after weight reduction.
After therapy, body weight, % BF and fat mass had all significantly decreased (p<0.001), while height and FFM had both significantly increased (p<0.001 ; p<0.05, respectively). There were no correlations between pre-therapy serum ghrelin and any of the following: initial height, weight, % overweight, % BF, fat mass, or FFM. However, after therapy, serum ghrelin levels were negatively correlated with body weight (rs=-0.544, p<0.01). Serum ghrelin levels increased significantly from pre- to post-therapy (113.9±30.7 to 129.6±42.9 fmol/ml, p<0.05). The rate of changes in ghrelin levels was negatively correlated with the rate of change in the % overweight (rs=-0.412, p<0.05).
These findings suggest that long-term weight reduction based on a combination of diet and exercise therapy lessens the severity of obesity and increases serum ghrelin levels in obese children.View full abstractDownload PDF (228K) -
TAKESHI KUKIDOME, KATSUJI AIZAWA, AI OKADA, KUMPEI TOKUYAMA, ICHIRO KO ...2007 Volume 56 Issue 4 Pages 429-436
Published: August 01, 2007
Released on J-STAGE: September 14, 2007
JOURNAL FREE ACCESS[Objective] This study examined the effects of resting metabolic rate (RMR), sleeping metabolic rate (SMR), and diet-induced thermogenesis (DIT) during acute weight loss in elite male wrestlers.
[Methods] Subjects were elite male wrestlers (n=6), who were instructed to reduce the body weight in seven days. RMR, SMR, and DIT were measured by indirect calorimetry in normal training phase and after rapid weight loss. Body composition and energy intake were also measured.
[Results] Energy intake significantly decreased in rapid weight loss phase (P<0.05). After the rapid weight reduction, percent reduction of body weight (-4.4%), fat mass (-17.5%), and total body water (-3.2%) significant compare with that of normal training phase (P<0.05). RMR(-15.2%), and SMR (-11.8%) significantly decreased during acute weight loss (P<0.05). DIT(-89.4%) tended to be decrease during acute weight loss.
[Conclusion] The present study suggests that rapid weight loss in elite male wrestlers causes decreases in RMR and SMR.View full abstractDownload PDF (201K)
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SEIICHI NAKAI, HIROMI SHIN-YA, TETSUYA YOSHIDA, AKIRA YORIMOTO, YOSHIM ...2007 Volume 56 Issue 4 Pages 437-444
Published: August 01, 2007
Released on J-STAGE: September 14, 2007
JOURNAL FREE ACCESSThe guidelines for the prevention of heat disorders during sports activities were established 13 years ago in Japan. Since then, various studies on preventive measures against heat disorders have been done, yielding new knowledge about its prevention. It has been reported that the incidence of heat disorders is high in children and the elderly, and heat acclimatization and clothing are the factors involved in this disorder. We proposed to lower the WBGT (wet-bulb globe temperature) limit for warning (discontinuation of hard exercise) from “28°C or more” to “25°C or more” (corresponding to an ambient temperature of 28°C) for non-acclimatized persons, children, the elderly, and persons wearing clothes covering the entire body. We also indicated that heat disorders can occur due to unpredictable causes, because the mechanism is very complicated.View full abstractDownload PDF (223K)
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2007 Volume 56 Issue 4 Pages 445-448
Published: August 01, 2007
Released on J-STAGE: September 14, 2007
JOURNAL FREE ACCESSDownload PDF (144K)
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