Relationship among gait parameters while walking with varying loads

金沢大学人間社会研究域人間科学系金沢大学自然科学研究科 生命科学専攻This study aimed to clarify the relationships between loads and gait changes and among gait parameters while walking with various loads. Fifteen healthy young male adults (mean age: 22.1±1.6 years) walked with four kinds of loads based on each subject\u27s body mass (0, 20, 40, and 60% of body mass: BM) on his back. Walking speed, cadence, stance time, swing time, double support time, step length, step width, walking angle, and toe angle were selected as gait parameters. Walking speed, cadence, stance time, and double support time changed significantly with loads. The walking speed showed significant correlations with the swing time at 0% BM (r=−0.64) and the walking angle at 60% BM (r=−0.52). Significant correlations were found between swing time and double support time at 0, 20, and 40% BM (r=0.53–0.63) and between walking speed and step length at 40 and 60% BM (r=−0.61, −0.67). In conclusion, walking with loads produces large gait changes. The relationship between swing time, double support time, and walking speed, as well as between walking angle, step length, and walking speed changes greatly with loads. These changes may occur in order to maintain a stable posture

Slow movement resistance training in women

A resistance training protocol of low intensity and short duration allows for increased training frequency and improved compliance. This study aimed to examine the short-term (response of growth hormone (GH) and testosterone after one exercise session) and long-term (change of fitness level and body fat percentage after the exercise period) effects of slow movement resi- stance training using the individual’s body mass (hiroNARI style training) in adult women and to clarify their subjective sense of training contin- uity. Nineteen healthy adult women performed hiroNARI style training three times a week for 12 weeks. This protocol consisted of 12 types of exercise for 7 muscle groups. GH and testos-terone increased significantly after one exercise session (70% and 23.3%, p < 0.05, respectively). Height and the circumferences of the upper arm (flexed), chest, waist, hip, and thigh changed si- gnificantly. Except for the upper arm circumfe- rence, these parameters improved significantly after 6 weeks. There were significant improvem- ents in measurements of physical fitness after 6 weeks including one leg raise with eyes closed, side step, and repeated sit ups for 30 s. After 12 weeks, anteflexion from a long sitting position improved as well. Triglycerides and HDL and LDL cholesterol changed significantly after 12 weeks. In conclusion, resistance training may have po- sitive effects and is associated with high comp- liance. However, it will be necessary to reexam- ine the training protocol for increasing back and lower limb muscle strength and necessary vari- ations to prevent overtraining of certain muscle groups

Gender difference in ability using the stretch-shortening cycle in the upper extremities

金沢大学人間社会研究域人間科学系石川県立大学Miyaguchi, K and Demura, S. Gender difference in ability using the stretch-shortening cycle in the upper extremities. J Strength Cond Res 23(1): 231-236, 2009-A gender difference in ability using the stretch-shortening cycle (SSC ability) in the upper extremities has not been studied in detail. This study aimed to devise an index to evaluate SSC ability during powerful elbow flexion and to examine its gender differences. Thirty-three men athletes (19.9 ± 1.0 years) and 21 women athletes (20.6 ± 1.2 years) with mastered SSC movements participated in this study. They pulled a 20% load of maximal voluntary contraction (MVC) by elbow flexion as quickly as possible with the dominant upper extremity from the following two preliminary conditions: a static relaxed muscle state (SR condition) and using a countermovement (SSC condition). The muscle power was measured accurately by a power measurement device, which adopted the weight loading method. The peak power under both conditions showed significantly higher values in men than in women. In both genders, the peak power showed significantly lower values in the SSC condition than in the SR condition (p < 0.05). The potentiation of using the SSC was not found in the peak power test. However, the initial power showed significantly higher values under the SSC condition (men: 37.2 ± 6.4 W; women: 17.4 ± 5.1 W) than in the SR condition (men: 18.3 ± 4.3 W; women: 11.2 ± 3.1 W). Hence, assuming a difference between initial muscle power outputs of the SR and SSC conditions as a difference in SSC ability, an SSC index was devised to evaluate the above ability. The SSC index showed significantly higher values in men (50.1 ± 12.4) than in women (32.1 ± 23.2). However, the individual difference of SSC ability was very large in women. The ability of women to use SSC in the upper extremities may be inferior to that of men. © 2009 National Strength and Conditioning Association

Evaluation of muscle power exerted by explosive gripping

金沢大学人間社会研究域人間科学系石川県立大学Demura, S and Miyaguchi, K. Evaluation of muscle power exerted by explosive gripping. J Strength Cond Res 23(2): 465-471, 2009-To establish the evaluation method for muscle power exerted by explosive gripping, this study aimed to examine the reliability of parameters and the muscle power output properties in both genders. Fifteen young men and 15 women participated in this study. Each subject carried out explosive grip tests twice using a simple muscle power measurement device (weight loading method), each time with 20, 30, 40, and 50% loads of maximum grip strength (MGS) by isometric contraction. Peak power was drawn from the product of the measured peak velocity and relative loads. The reliability of each parameter in all loads was good (interclass correlation coefficient <0.75) for both genders. The MGS showed insignificant correlation with all parameters. Peak power values were larger in men than in women for all loads, and the women\u27s values were 44.5-52.2% of the men\u27s. A large gender difference was found for 20% MGS. In conclusion, the reliability of muscle power parameters measured by the measurement device in this study is high. It was judged that the device used in this study can properly evaluate the gender difference in muscle power output properties by explosive gripping. © 2009 National Strength and Conditioning Association

Age and sex differences in controlled force exertion measured by a computing bar chart target-pursuit system

金沢大学人間社会研究域人間科学系京都薬科大学 基礎科学系 健康科学分野This study aimed to examine the age and sex differences in controlled force exertion measured by the bar chart display in 207 males (age 42.1 ± 19.8 years) and 249 females (age 41.7 ± 19.1 years) aged 15 to 86 years. The subjects matched their submaximal grip strength to changing demand values, which appeared as a moving bar chart on the display of a personal computer. The subjects performed the controlled force exertion test using the dominant hand three times with 1-min intervals (one trial was 40 sec) after one practice trial. A total of the differences between the demand value and the grip exertion value for 25 sec was used as the evaluation parameter. The errors in controlled force exertion showed a right-skewed distribution in both sexes but showed a normal distribution after logarithmic transformation (males, W =.06; females, W =.74; p >.05). In addition, the errors in controlled force exertion tended to increase constantly with age in both sexes. Significant linear regressions were identified (r2males =.88, r2females =.81), but there was no significant difference in the increase rate of both sexes. The results of the analysis of variance and multiple comparisons showed insignificant sex differences among means, except for those in individuals older than 70 years; significant differences between means in the older than 40-year-old age group and the 20-year-old age group were found in both sexes. Individual differences were almost the same in both sexes (CVmales = 20.0∼34.8, CVfemales = 17.7∼36.2). Errors in controlled force exertion showed a nonsignificant sex difference and increased gradually with age in both sexes but increased remarkably with age after 40 years of age. Copyright © Taylor & Francis Group, LLC

The role of eye movement in upright postural control

金沢大学人間社会研究域人間科学系秋田県立大学 総合科学教育研究センターVision contributes to upright postural control by providing afferent feedback to the cerebellum. Vision is generally classified into central and peripheral vision. In measurements of postural sway, in which participants are required to maintain a stable upright posture while fixating on a visual target, non-retinal eye positional information due to the fixation is used as well as the retinal information from both visual fields. However, little is known about the role of non-visual eye positional information in postural control. This study examined the role of non-visual eye position information in upright postural control by comparing participants\u27 centre of pressure (COP) sway between two experimental conditions: (1) a space-fixed visual target condition (control), in which eye movement was not controlled, and (2) a head-fixed visual target condition (treatment), in which eye movement was inhibited. Using 12 university students, COP sway and electrooculograms (EOG) were measured under both conditions. In the space-fixed condition, participants maintain an upright posture while fixating on a visual target fixed on a screen 1 m in front of them. In the head-fixed condition, participants maintained an upright posture while gazing at a target moving in sync with their head sway on the screen. The COP was evaluated by path length, area, root mean square, velocity and position. Eye movements were evaluated by the mean eye movement angle. The mean eye movement angle was significantly larger in the vertical direction then in the horizontal direction in both experimental conditions and was also found to be larger in the space-fixed condition than in the head-fixed condition. No significant different was found in any COP parameter between both conditions. It was suggested that non-visual eye position information from the external eye muscles to the sensory perception system contributes little to postural stabilisation under the measurement conditions used in this study. © Springer-Verlag Italia 2009