Yoshinori Nagasawa

Development of an Apparatus to Estimate Coordinated Exertion of Force

The purpose of this study was to develop a practical apparatus for estimation of the coordinated exertion of force and to develop methods for display, test duration, and sampling interval. A total of 84 healthy male college students were required to match their grip strength to a changing demand value appearing on the display of a personal computer (using two descriptions in the form of a bar chart and wave form). The variables were the maximal difference and the total sum of the differences between demanded and produced grip strength over time. In estimating coordinated exertion of force, an actual force (kgf) scale was more effective than a relative force (%) scale. Reliability tests indicated that a 30-sec. test was effective. Both bar chart and wave form displays were effective.

Ability to coordinate exertion of force by the dominant hand: comparisons among university students and 65- to 78-year-old men and women.

The purposes of this study were to examine the characteristics of ability to coordinate exertion of force in 60 healthy older people (30 men, 30 women) from the viewpoint of sex differences and to compare their performance with those of 60 healthy university students (30 men, 30 women). The test of ability to coordinate exertion of force was conducted by having the subject fit the exertion value of grip strength to a changing demand value appearing on the display of a personal computer (using a bar chart-description form). The changes in the demand value were tracked. The variable estimating ability to coordinate exertion of force was the total sum of the differences between demand and the produced grip strength induced by time lapses. The ability to coordinate exertion of force in the older subjects was inferior to that of the younger subjects, and large individual differences were observed. Unlike the younger subjects, the means of the ability to coordinate exertion of force of the older subjects significantly decreased between trials. The ability to coordinate exertion of force of the older women was significantly inferior to that of the older men, but the means of the measurements among three trials shows a similar tendency to decrease in both sexes.

LATERAL DOMINANCE OF LEGS IN MAXIMAL MUSCLE POWER, MUSCULAR ENDURANCE, AND GRADING ABILITY '

The purpose of this study was to examine lateral dominance in maximal muscle power, muscular endurance, and grading ability, using isokinetic muscular strength in knee extension and flexion. The subjects were 50 healthy male students whose ages ranged from 19 to 23 years (M height: 173.6 ±6.2 cm, M weight: 67.2 ± 6.8 kg). Their dominant legs for power exertion and for functional use were based on questionnaire items selected from those used in previous studies. The angular velocities of extension and flexion for exerting maximal muscle power were 60, 180, and 300 · sec.−1. A continuous exertion 30 times at an angular velocity of 180 · sec.−1 was used as the load for muscular endurance. For grading ability, 25%, 50%, and 75% of the maximal muscle strength at angular velocities of 60 and 180 · sec.−1 were the required values, and the difference between these values and the exerted muscular strength was evaluated. The dominant leg and nondominant leg were compared for both power exertion and functional use. There was no lateral dominance in maxima] muscle power and muscular endurance. In muscular endurance, especially, some subjects showed one leg superior in power exertion and some superior in functional use. Lateral dominance was noted across maximal muscle power and muscular endurance in grading ability. The dominant leg tended to be better than the nondominant leg in functional use. However, lateral dominance was not remarkable for flexing motion and in exertion for a short time.

CONCURRENT VALIDITY OF TESTS TO MEASURE THE COORDINATED EXERTION OF FORCE BY COMPUTERIZED TARGET PURSUIT

The purpose of this study was to examine concurrent validity of a new test for coordinated exertion of force. Coordinated exertion of force was measured using computerized target pursuit from the following viewpoints: the relations between the new test, a pursuit-rotor test, and a pegboard test. College students (24 men and 24 women) were required to change their grip exertion to match changing demand values (displayed in either a bar chart or a wave form) appearing on the display of a personal computer. The sum of the differences between the demanded values and grip-exertion values for 25 sec. was a parameter to evaluate the new test. The reliabilities of the new test, the pursuit-rotor, and the pegboard test were acceptable (ICC = .70 to .99). Scores on the new test showed low correlations with the pursuit-rotor and the pegboard test. The relation between the two different displays in the new test was significant but low (r = .49, p<.05). It was inferred that the new test measures a somewhat different ability than that measured by the pursuit-rotor and pegboard test and that the abilities tested by the types of displayed demand values are somewhat different.

The validity and reliability of relative body fat estimates and the construction of new prediction equations for young Japanese adult males

The aims of this study were to assess the reliability and validity of three methods of bioelectrical impedance analysis (based on induction between the hand and foot, between one foot and the other foot and between one hand and the other hand) and the skinfold method, and to construct prediction equations for total body density by examining cross-validity in young Japanese adult males. The participants were 50 Japanese males aged 18-27 years (height 1.72 - 0.06 m, body mass 64.9 - 9.0 kg; mean - s ), each of whom was measured twice using each of the four methods. Relative body fat based on underwater weighing was used as the criterion for validity. To construct prediction equations for body density, we used multiple regression analysis, whereby all possible combinations were examined. The reliability of all three bioelectrical impedance methods was high ( R = 0.999). Three new prediction equations were constructed for the hand-foot method, foot-foot method and skinfold method. The cross-validity of the equations was guaranteed. The relative body fat calculated using the new equations did not differ from that based on the underwater weighing method.

Relations between Perceptual and Physiological Response during Incremental Exercise Followed by an Extended Bout of Submaximal Exercise on a Cycle Ergometer

The purpose of this study was to examine the relations of ratings of perceived exertion (RPE) of the legs, chest, and overall body with physiological responses (heart rate and oxygen uptake) both during incremental cycling exercise and the recovery stage (submaximal light exercise after total exhaustion). Subjects were 10 healthy university males ages 18 to 23 years (M age = 20.5 yr., SD= 1.4 yr.) who performed incremental cycling exercise until exhaustion after 1-min. rest and unloaded cycling for 2 min. They then continued to exercise at a constant load of 30 Watts (used for cooling down; recovery stage) for a total of 25 min. Oxygen uptake and heart rate were measured, and three types of RPE were done; Respiratory (chest; RPE-R), Peripheral (legs; RPE-P), and Overall (overall body; RPE-O) during the exercise and recovery stage. All variables during exercise and RPE-R and RPE-P during recovery stage showed significant linear changes. RPE-O and physiological exercise intensity (oxygen uptake and heart rate) in the recovery stage showed significant curvilinear changes (quadratic). RPE-P were significantly higher than RPE-R both during exercise and the recovery stage and the variables highly correlated (r ≥.88, p <.05). At the point of exhaustion, RPE-P and RPE-O almost reached a peak, but RPE-R did not. In the exercise period until exhaustion, the regression coefficient of RPE-R (.38) was significantly lower than that of RPE-P (.56) and RPE-O (.50), and RPE-R increased according to an increase of the incremental load, but the amount was significantly lower than those of RPE-P and RPE-O. In the recovery stage after exhaustion, the regression coefficient of RPE-O (−1.35) was significantly greater than that of RPE-P (−1.07). A decrease in RPE-O corresponded to a decrease in heart rate and oxygen uptake, but RPE-P did not, and the recovery of RPE-P tended to be late. The results suggest that relations for the physiological responses of heart rate, oxygen uptake, and RPE, and between each RPE in the recovery stage differed from those during exercise until exhaustion.

An Examination of Practice and Laterality Effects on the Purdue Pegboard and Moving Beans with Tweezers

The purpose of this study was to examine the relation of practice or learning and laterality on the Purdue Pegboard and the Moving Beans with Tweezers test. The subjects were 30 right-handed, healthy young male adults (age: M = 21.1, SD= 1.9 yr.). The subjects performed both tests five times with each hand. A two-way analysis of variance (hand × trial) for scores on the Purdue Pegboard showed that Trial 1 had a significantly lower mean than Trials 4 and 5 with the dominant hand, and scores on Trials 1 and 3 were lower than that on Trial 5 for the nondominant hand. For the Moving Beans with Tweezers test, Trial 1 had a significantly lower score than Trial 5 with the nondominant hand. The dominant hand produced significantly higher values on all trials of both tests. Intraclass correlation coefficients of Trials 2 and 3 were high, and means were significantly higher for the dominant hand. A correlation between other tests was not high (r = 37–.46) for both hands. All correlations among five trials on both tests were significant and high (Purdue Pegboard-Dominant: average r = .72, |r| = .60–.80, Purdue Pegboard-Nondominant: average r = .59, |r| = .43–.76), (Moving Beans-Dominant: average r = .74, |r| = .57–.81, Moving Beans-Nondominant: average r = .71, |r| = .55–.87). Correlations among five trials for the ratio of dominant:nondominant hand on both tests were significant and moderate (Moving Beans: average r =.28, |r| = .08–.57, Purdue Pegboard: average r = .41, |r| = .19– .56). Performance with the dominant hand is superior to that of the nondominant hand on both tests. Practice effects are found for both tests across five trials. The Moving Beans with Tweezers test also showed laterality of practice effects. The two tests may measure different abilities.

Static One-Legged Balance in Soccer Players during Use of a Lifted Leg

The goal was to describe static one-legged balance during use of a lifted leg and to compare balance between the dominant and nondominant legs of soccer players. Participants were 17 male soccer players and 17 untrained male students (control). Balance ability was evaluated with four sway measures: sway velocity, anterior–posterior sway, medial–lateral sway, and high-frequency sway. Soccer players had smaller magnitude mean anterior–posterior and medial–lateral sway than untrained students. Although mean sway velocity and anterior–posterior sway were higher with the dominant leg than in the nondominant leg of the control group, there was no significant difference on any sway factor between the two legs of the soccer group. In conclusion, the soccer players were observed to have superior static one-legged balance during use of a lifted leg, and there is no difference in balance for the two legs in the soccer group.

Force developmental phase and reliability in explosive and voluntary grip exertions.

The purposes of this study were to clarify the reliability of two types of grip exertions, explosive grip exertion and voluntary grip exertion up to the maximal grip strength and to examine their force patterns using force-time parameters. Subjects were 100 healthy young male volunteers (age: 17.8 ±2.50 yr.) who had no upper limb injury. Grip strength was measured two times with voluntary grip and then two times with explosive grip. 11 parameters derived from the force-time curve were selected to measure the developmental phase of muscle contraction. The reliability of maximal grip strength in explosive and voluntary grip exertions was very high (intraclass correlation = .95, .93). The difference between two trials in explosive grip tended to be smaller than that for voluntary grip, and reliability of the exertion pattern was higher for explosive grip than voluntary grip. The times to reach 90% of the maximal grip strength and the maximal grip strength in explosive grip were shorter than those in voluntary grip. The other 8 force-time parameters had higher values in explosive grip than voluntary grip and higher reliabilities. The force-time parameters reflect the properties of explosive exertion. The results suggest the possibility that static explosive strength could be evaluated using these force-time parameters.

Effect of bag holding on the center of foot pressure and the lower leg muscle activities

Abstract This study examined the influence of holding a bag with one hand on the center of foot pressure (COP) and the electromyographic responses in lower leg muscles. Thirteen healthy male adults participated in this study to keep an upright posture while holding a load with the dominant hand with four bag weight conditions (0%, 15%, 30%, and 45% of maximal voluntary contraction (MVC) of the jerk strength). Integrated Electromyography (iEMG) and mean power frequency (MPF) of EMG were calculated to estimate the degree of muscle activity and fatigue in the tibialis anterior and soleus that are involved in ankle joint control. Body sway was evaluated by the mean position of left-right (X) and front-back (Y) axis sway and the following 4 body sway factors; unit time sway factor (F1), front-back sway factor (F2), left-right sway factor (F3), high frequency band power spectrum factor (F4). When holding a bag at 45% MVC or more of the jerk strength with a single hand for one minute, muscle activity in the lower leg on the side of the bag increased markedly, and muscle fatigue was induced in the antigravity muscles of both legs. As a result, anteroposterior sway increased to a short, quick sway.