Tomohiko Murase

Bio: Tomohiko Murase is an academic researcher from Aichi University. The author has contributed to research in topics: Physical fitness & Multiple discriminant analysis. The author has an hindex of 4, co-authored 10 publications receiving 138 citations.

Grip posture and forces during holding cylindrical objects with circular grips.

Abstract: Individual finger position and external grip forces were investigated while subjects held cylindrical objects from above using circular precision grips. Healthy females (n = 11) and males (n = 15) lifted cylindrical objects of various weights (0.5, 1.0 and 2.0 kg), and varied diameters (5.0, 7.5 and 10.0 cm) using the 5-finger grip mode. The effects of 4-, 3- and 2-finger grip modes in the circular grip were also investigated. Individual finger position was nearly constant for all weights and for diameters of 5.0 and 7.5 cm. The mean angular positions for the index, middle, ring and little fingers relative to the thumb were 98 degrees, 145 degrees, 181 degrees, and 236 degrees, respectively. At the 10-cm diameter, the index and middle finger positions increased, while the ring and little finger positions decreased. There were no differences in individual finger position with regard to gender, hand dimension, or hand strength. Total grip force increased with weight, and at diameters greater or lesser than 7.5 cm. Total grip force also increased as the number of fingers used for grasping decreased. Although the contribution of the individual fingers to the total grip force changed with weight and diameter, the thumb contribution always exceeded 38% followed by the ring and little fingers, which contributed approximately 18-23% for all weights and diameters. The contribution of the index finger was always smallest (> or = 11%). There was no gender difference for any of the grip force variables. The effects of hand dimension and hand strength on the individual finger grip forces were subtle.

Comprehensive evaluation of selected methods for assessing human body composition.

Abstract: The present study investigated the validity, reliability, objectivity, and practicability of methods with skinfold caliper (SF), ultrasound (US), bioelectrical impedance (BI), and sulfur hexafluoride (SHD) using identical subjects, and evaluated comprehensive usefulness by comparing selected methods or equations. In examining validity, underwater weighing (UW) was employed to obtain the criterion of validity. The subjects were healthy Japanese, 16 males and 15 females, aged 18 to 32 years. The prediction equation developed by Nakadomo et al. (1990b) was considered to be suitable for BI. With respect to the validity, BI and SHD assessing total body when estimating body composition would be more valid than those assessing partial subcutaneous skinfold thickness. A comprehensive evaluation through an examination with respect to the validity, reliability, objectivity, and practicability suggests that the BI could be the best method to assess human body composition in vivo.

Contribution of physical fitness component to health status in middle-aged and elderly males.

Abstract: This study determined the physical fitness component that contributes to improving and maintaining health status for each age group as well as quantifying the degree of the relationship between health status and physical fitness in middle-aged and elderly females. The participants were 2,371 females aged 30 to 69 years. Ten physical fitness tests and medical checkups were performed. The participants were divided into a healthy group and an unhealthy group according to health status. Multiple discriminant analysis was applied to the multivariate data. Correct discriminant probabilities of the multiple discriminant function to discriminate the healthy and unhealthy groups for females ranged from 63.0% to 77.5%. These results suggest that there is a relatively high relationship between health status and physical fitness level for middle-aged and elderly females. With each individual's discriminant score calculated by the obtained multiple discriminant function as the index of the degree of health, the Pearson's correlation coefficient of the discriminant score and the performance in each physical fitness test were calculated. The aging change from 30 to 69 years old was classified into four patterns according to the contribution. The result of this study is considered to be useful as objective data to prepare an exercise program considering the contribution of the physical fitness component of health status.

Changes in Healthy Childhood Lifestyle Behaviors in Japanese Rural Areas

Abstract: BACKGROUND Unhealthy lifestyles during childhood constitute a public health problem in Japan. However, current health education in Japan is ineffective in counteracting them. Previous studies contend that healthy lifestyles in children vary by academic grade and sex. This study examined changes throughout childhood suggests some intervention points for lifestyle education. METHODS The participants were 2833 elementary and junior high school students living in Japanese rural areas. Data on 26 variables assigned to 5 subfactors were collected. We estimated the composite score of each subfactor on the basis of item response theory. A 2-way ANOVA and a graph review were performed to explore the differences and changes by sex and grade. RESULTS Most of the main effects for sex and grade were statistically significant. Lifestyle behaviors acquired early in elementary school were lost as students progressed to higher grades. CONCLUSIONS The research indicated the following emphases: (1) Physical activity and leisure habits should be focused on girls and hygiene habits on boys; (2) Continuous education for a healthy lifestyle is essential to maintain good health among children; (3) Education for healthy lifestyle can be classified into 2 important stages such as for dietary and sleeping habits, education from the upper grades of elementary school is important, whereas for other routine activities, reeducation in junior high school is effective.

Structure of motor variability in marginally redundant multifinger force production tasks.

Abstract: The framework of the uncontrolled manifold hypothesis (UCM hypothesis) was applied to the analysis of the structure of finger force variability during oscillatory force production tasks. Subjects produced cycles of force with one, two (index and middle), or three (index, middle, and ring) fingers acting in parallel against force sensors mounted inside a small frame. The frame could be placed on the top of a table (stable conditions) or on a 4-mm-wide supporting surface (unstable conditions). Subjects were less variable when they used two fingers than when using one finger; adding the third finger did not change indices of variability of the performance. Components of finger force variance that did (VUN) or did not (VCOMP) change the value of a particular functional variable were computed for two control hypotheses: (1) at each time, the subjects tried to stabilize the total value of force (force-control); and (2), at each time, the subjects tried to stabilize the total moment produced with respect to an axis parallel to the hand/forearm (moment-control). Most subjects showed selective stabilization of moment and destabilization of force throughout most of the force cycle, in both stable and unstable conditions. The shapes of VUN and VCOMP suggested a possibility of selective compensation of timing errors across fingers within force cycles. One subject showed different relations between VUN and VCOMP, suggesting that these relations did in fact reflect particular central strategies of solving the tasks. The UCM method is applicable to force production tasks. It allows the comparison of control hypotheses in a quantitative way and unveils central strategies of control of redundant motor systems. Within this approach, redundancy (rather, abundance) is not a problem but an inherent part of a solution for natural motor tasks.

Redefining overweight and obesity in rheumatoid arthritis patients

Abstract: Objectives: To assess whether body mass index (BMI) and body fat (BF) differ between rheumatoid arthritis (RA) patients, patients with non-inflammatory arthritis (osteoarthritis, OA) and healthy individuals, and whether disease specific measures of adiposity are required to accurately reflect BF in these groups. Methods: 641 individuals were assessed for BMI (kg/m 2 ) and BF (bioelectrical impedance). Of them, 299 (174 RA, 43 OA and 82 healthy controls (HC)) formed the observation group and 342 (all RA) the validation group. RA disease characteristics were collected. Results: ANOVA revealed significant differences between disease groups for BMI (p 1,294 = 5.10, p 1,293 = 22.43, p 1,293 = 380.90, p 2, 293 = 18.7, p 2 (p 2 = 0.769, p AG = 6.17; CV = 8.94). Conclusions: In individuals with RA, BMI cut-off points should be reduced by 2 kg/m 2 (that is, to 23 kg/m 2 for overweight and 28 kg/m 2 for obesity). The equation developed can be used to accurately predict BF from BMI in RA patients. These findings may be important in the context of the cardiovascular comorbidity of RA.

A mode hypothesis for finger interaction during multi-finger force-production tasks

Abstract: Finger forces are known to change involuntarily during multi-finger force-production tasks, even when a finger's involvement in a task is not consciously changed (the enslaving effect). Furthermore, during maximal force-production (MVC) tests, the force produced by a given finger in a multi-finger task is smaller than the force generated by this finger in its single-finger MVC test (the force-deficit effect). A set of hypothetical control variables – modes – is introduced. Modes can be estimated based on individual finger forces during single-finger MVC tests. We show that a simple formal model based on modes with only one free parameter accounts for finger forces during a variety of multi-finger MVC tests. The free parameter accounts for the force-deficit effect, and its value depends only on the number of explicitly involved fingers. This approach offers a simple framework for the analysis of finger interaction during multi-finger actions.

Grip Force Vectors for Varying Handle Diameters and Hand Sizes

Abstract: Grip force was measured along two orthogonal axes and vector summed. Sixty-one participants recruited from a manufacturing facility (29 men and 32 women) grasped instrumented cylinders (2.54, 3.81, 5.08, 6.35, and 7.62 cm diameter) using a maximal voluntary power grip. Two orthogonal force measurements relative to the third metacarpal were resolved into a magnitude and corresponding angle. On average, magnitude increased 34.8 N as handle diameter increased from 2.54 cm to 3.81 cm, and then monotonically declined 103.8 N as the handle diameter increased to 7.62 cm. The average direction monotonically decreased from 59.2 degrees to 37.7 degrees as handle diameter decreased from the largest to the smallest. When the diameter was smallest, the greatest force component, Fx (168.6 N), was in the direction where the fingertips opposed the palm. Conversely, when the diameter was largest, the smallest component, Fx (77.7 N), was in the same direction. These values are averaged for the left and right hand. The angle for the largest diameter increased with increasing hand size. These relationships should be useful for the design of handles that require gripping in specific directions, such as for hand tools and controls. Actual or potential applications of this research include the design of handles that require gripping in specific directions, such as for hand tools and controls, that reduce effort, and that prevent fatigue and overexertion.