Masanobu Uchiyama

Centre of pressure sway characteristics during static one-legged stance of athletes from different sports

Abstract The frequency of one-legged stance and two-legged stance differs considerably among sports. We therefore expect the balance ability of athletes from different sports to vary. This study compared the sway characteristics during a static one-legged stance of soccer players, basketball players, swimmers, and non-athletes. The centre of pressure sway during one-legged stance of ten male participants representing each of the four groups was measured using a stabilometer. Centre of pressure sway was assessed by four sway factors: sway velocity, anterior-posterior sway, horizontal sway, and high-frequency sway. None of the four groups of participants showed significant differences in body sway between standing on the dominant leg and standing on the non-dominant leg. The soccer players had more high-frequency sway and less anterior-posterior sway and horizontal sway than the basketball players, swimmers, and non-athletes. These results suggest that soccer players have superior ability to maintain a stable one-legged stance. Further study is required to determine how much of the superior balance ability in soccer players is innate and how much is developed through training, as well as to determine the relationship between balance ability and playing performance.

Setting the criterion for fall risk screening for healthy community-dwelling elderly

This study aimed to develop a criterion for screening high risk elderly using Demuras fall risk assessment chart (DFRA), compared with the Tokyo Metropolitan Institute of gerontology (TMIG) fall risk assessment chart. Participants included 1122 healthy elderly individuals aged 60 years and over (380 males and 742 females) 15.8% of whom had experienced a fall. We assessed fall risk of the elderly by DFRA and TMIG. To develop a criterion for screening high fall risk subjects among community-dwelling elderly, receiver-operating-characteristic (ROC) analysis was conducted using fall experience (separated into the categories of faller and non-faller) and the following fall risk scale scores: (1) TMIG score, (2) DFRA score, and (3) potential for falling score according to the DFRA (summing the scores of three items). In ROC analyses, the area under the ROC curve (AUC) for evaluating the potential for falling gave a value of 0.797 (95% CI=0.759-0.834) which proved better than the evaluation of the overall TMIG (0.654, 95% CI=0.600-0.706) and DFRA scores (0.680, 95% CI=0.633-0.727). Assessment of the potential for falling and fall experience are of benefit in screening for elderly persons deemed to be at a high fall risk. Further examinations based on the prospective data setting will be required.

Influence of cell phone email use on characteristics of gait

Abstract Previously, gait had been considered an automatic and rhythmical movement that uses minimal attentional resources. The relationship between attention and gait has been revealed in recent research. However, in young adults in particular, the influence of using a cell phone – which is used frequently in daily life and considered to require high attentional demands – on gait has not been demonstrated. In this study, we examined the influence of mobile phone use on gait. Thirty healthy college students (15 males, 15 females) walked through a normal straight course with or without an obstacle under two different walking conditions while either using the email function of the cell phone or walking without a cell phone. The participants walked at a normal speed on a 10-m walkway. In walking conditions with an obstacle, an obstacle (17 cm in height) was set at the mid-point of the walkway. The following gait parameters were calculated: velocity, stride length, stride width (cm), and stance phase of one foot (just before an obstacle, one and two steps before the obstacle). Velocity and stride width decreased and the stance phase increased during walking while operating a cell phone. The stance phase just before an obstacle and stride length increased while operating a cell phone with an obstacle in the way. Gaze fixations and the high attention required to use the email function of the device may result in greatly disturbed gait.

Force-time parameters during explosive isometric grip correlate with muscle power

Although explosive isometric contraction provides little work toward the outside, force-time parameters of the rising phase of the force-time curve may be able to predict muscle power. The purpose of this study was to examine the relationship between muscle power with work (power grip) and force-time parameters during the rising phase in explosive isometric grip. Fifteen healthy young adult males participated in this study. Power grip was measured using loads of 20%–50% of maximal voluntary contraction (MVC) (peak isometric force). Subjects pulled explosively on a grip bar held with the second digital joints without the thumb. Peak power was calculated from peak velocity and load. Explosive isometric grip was measured using a hand dynamometer. Time-series data of both tests were sampled by an analog-to-digital interface. Both tests were performed with the subjects seated with a sagittal and horizontal position of the arm supported by an armrest. Peak power in the power grip test tended to be larger with an increase of the load, but there was no significant difference between 40% and 50% MVC. Only the peak power in 50% MVC significantly correlated with peak grip force (r=0.52, p<0.05). The force-time parameters related to the peak rate of the rising force phase in explosive isometric grip significantly correlated with the peak powers (30%–50% MVC, r=|0.58−0.78|). Peak rate of the rising force phase in explosive isometric grip may be useful for predicting muscle power with loads between 30%–50% MVC.

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.

Comparison of the Body-Sway Characteristics of Young Adults Compared to Healthy Elderly and Elderly with Equilibrium Disorder

The study compared body-sway characteristics of 380 young adults, 342 generally healthy elderly without disequilibrium disorders, and a group of 33 elderly with disequilibrium disorders. Center of foot pressure (COP) was measured for 1 min. using an Animas stabilometer G5500 with a data sampling frequency of 20 Hz. Four high reliability measures were used to evaluate body sway (unit time sway, front-back sway, and a left-right sway, and high frequency band power). Unit time sway, left-right sway, and high frequency band power were significantly larger for the group of elderly with disequilibrium disorders, and smaller for the healthy elderly people and young adults, in that order. Front-back sway was significantly larger in the elderly with disequilibrium disorders and healthy elderly than in young adults. The elderly with disequilibrium disorders had a larger and faster sway than young adults as well as the healthy elderly, particularly in the left-right direction. It appears aging was specifically associated with larger influence on the front-back sway.

Selection of useful items for fall risk screening for community dwelling Japanese elderly from the perspective of fall experience, physical function, and age level differences.

This study aimed to examine useful items for screening the fall risk of community dwelling elderly from various perspectives, including fall experience, physical function level, and age level difference. 968 independently living elderly persons over the age of 60 (age: 70.0 ± 7.0) responded to 80 fall risk items representing 7 factors (physical function, fall history, using devices, fear of falling and inactivity, dosing, disease and disability, and environment) and an ADL questionnaire. The high fall risk response rate was calculated for each item and tested for statistical significance among age groups and those with and without fall experience. Cramers V was calculated to examine the relationship between each item and the ADL. In addition, we selected items with significant differences in the high fall risk response rates between the faller and the non-faller groups, a significant relationship with ADL, and a significant difference among age groups. A total of 40 useful items were selected from each fall risk factor (decrease in physical function: 21 items, fall history: 2 items, device usage: 3 items, fear of falling and inactivity: 5 items, dosing: 0 items, disease and disability: 8 items, and environment: 1 item). Selected items can comprehensively and properly assess the fall risk of the healthy elderly as compared with existing questionnaires.

Influence of Anaerobic and Aerobic Exercises on the Center of Pressure During an Upright Posture

This study was designed to examine the influence of anaerobic and aerobic exercise, using a cycle ergometer, on upright standing postural control in addition to physiological and psychological responses. During an upright standing posture, 15 healthy male participants were measured for center of pressure (COP), physiological parameters (heart rate, systolic and diastolic blood pressures, and blood lactate concentration), and the ratio of perceived exertion before and after the exercises. They performed a maximal voluntary pedaling exercise for 10 seconds two times under anaerobic exercise conditions and then at 50% of maximal aerobic power for 60 minutes at 60 rpm under aerobic exercise conditions. Measurements were conducted before, immediately after and at 5, 10 and 15 minutes after the exercises. Body sway was recorded by a COP measurement device G5500 (ANIMA, Japan) with three vertical load sensors. COP sway was assessed by mean position of COP sway in the anteroposterior and mediolateral directions as well as the sway area and path length. Three COP parameters regarding sway area and velocity were significantly higher immediately after the exercises than at the other times. In conclusion, the influence of the two exercise protocols on postural control is detected by sway area and velocity. However, the exercise-induced increase of sway velocity recovers earlier than the physiological parameters (heart rate, systolic blood pressure, and blood lactate concentration). It would appear that both prolonged aerobic exercise and high-intensity anaerobic exercise have a relatively small influence on upright standing postural control in healthy young males.

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.

Examination of factors affecting gait properties in healthy older adults: Focusing on knee extension strength, visual acuity, and knee joint pain

Background and Purpose:Gait properties change with age because of a decrease in lower limb strength and visual acuity or knee joint disorders. Gait changes commonly result from these combined factors. This study aimed to examine the effects of knee extension strength, visual acuity, and knee joint pain on gait properties of for 181 healthy female older adults (age: 76.1 (5.7) years). Methods:Walking speed, cadence, stance time, swing time, double support time, step length, step width, walking angle, and toe angle were selected as gait parameters. Knee extension strength was measured by isometric dynamometry; and decreased visual acuity and knee joint pain were evaluated by subjective judgment whether or not such factors created a hindrance during walking. Results:Among older adults without vision problems and knee joint pain that affected walking, those with superior knee extension strength had significantly greater walking speed and step length than those with inferior knee extension strength (P < .05). Persons with visual acuity problems had higher cadence and shorter stance time. In addition, persons with pain in both knees showed slower walking speed and longer stance time and double support time. Conclusion:A decrease of knee extension strength and visual acuity and knee joint pain are factors affecting gait in the female older adults. Decreased knee extension strength and knee joint pain mainly affect respective distance and time parameters of the gait.