Analysis of postural stability using foam posturography in patients with persistent postural-perceptual dizziness.

BACKGROUND/OBJECTIVE: Persistent postural-perceptual dizziness (PPPD) is worsened in a standing posture, or by body movement, or visual stimulation. We aimed to evaluate postural stability in PPPD patients using foam posturography and to investigate the dependence on visual and somatosensory input in the standing posture. METHODS: Foam posturography was performed on 53 PPPD patients, and data from the PPPD patients were compared with the data from an age- and sex-matched healthy controls. The PPPD patients were divided into four groups based on the findings of vestibular function tests and the effect of vestibular function on posturographic data was examined. RESULTS: Romberg's ratios were significantly higher in PPPD patients than in controls. The median Romberg's ratios in PPPD patients with normal vestibular function were also higher than those in controls. However, foam ratio was significantly lower in PPPD patients than in controls. The median foam ratios in PPPD patients with vestibular dysfunction were also lower than those in controls. CONCLUSIONS: In a standing posture, PPPD patients may be more dependent on visual input and less dependent on somatosensory input than healthy subjects. Higher dependence on visual and lower dependence on somatosensory input in PPPD may be a feature unaffected by vestibular function.

Frequency analyses of posturography using logarithmic translation.

Background: Power-spectral analysis of the centre of pressure (CoP) frequencies of posturography provides exponentially approximated distributions, whereas logarithmic translation enables linear approximation.Objectives: Frequency analyses were adopted for posturography of healthy subjects and patients with spinocerebellar degeneration (SCD) using logarithmic translation to determine its clinical usefulness for managing the elderly and patients with disequilibrium.Material and methods: We included 172 healthy subjects and 47 SCD patients. Posturography was performed with the eyes fixated and closed, with and without foam rubber. The power-spectral data of the CoP were obtained with the maximum entropy method. Power-spectral data were logarithmically translated for quantitative evaluation.Results: For teenagers, high-frequency fluctuations were dominant and attributable to proprioceptive compensation due to immature postural control. In elderly populations, the increased frequency in the lateral direction was characterised by three peaks indicating postural disturbances attributed to three sensory inputs. The disappearance of one peak in the anteroposterior fluctuation indicates a decrease in vestibular contribution. The foam rubber and the closed-eye condition enhanced fluctuations in two peaks. There were differences in power-spectral distributions of two peaks between the healthy subjects and SCD patients.Conclusions: Logarithmic power-spectral data distribution could provide an age- and disease-specific novel and visually-comprehensible parameter.

Characteristics of the life habits of obese students at one of Japan's National Colleges of Technology.

Aim This study clarified the characteristics of life habits of obese Japanese male students at the National Colleges of Technology, Japan. Materials and methods Healthy students aged 15-19 years answered a questionnaire containing 21 items on the following five categories of life habits: general exercise, meals, sleeping, leisure activity and illness or injury history. The subjects were divided into three groups based on the criteria of body mass index (BMI) and body fat percentage (%BF): non-obese (%BF < 20%, n = 420), overweight obese (%BF ≥ 20% and BMI ≥ 25, n = 99), and hidden obese (%BF ≥ 20% and BMI < 25, n = 60). The mean differences in waking time, bedtime and amount of time spent walking, sleeping and watching TV per day were examined using one-way analysis of variance (ANOVA) and chi-square tests for each item. Results The overweight obese and hidden obese groups engaged in less exercise time, were more likely to eat until they were full at meals and were less likely to eat between meals or late at night than the non-obese group. In addition, the non-obese group had significantly later waking times and significantly less TV-watching time than the overweight obese group. There were no significant differences with respect to leisure activity and illness or injury history among the three groups. Many students in all groups had regular waking times and were not performing any leisure activities. Conclusion The findings suggest that obese students may need further guidance to help them maintain a healthy life and appropriate weight.

Differences in leg muscle activity and body sway between elderly adults able and unable to maintain one-leg stance for 1 min: the effect of hand support.

BACKGROUND: One-leg stance (OLS) training is often used to prevent falls in the elderly. The burden imposed on the supporting lower limb during OLS may differ depending on whether hand support is used, particularly in patients with decreased lower-limb strength. AIMS: Here we examined the effect of hand support on leg muscle activity and body sway during OLS in elderly subjects able to maintain OLS for 1 min unaided [able group (AG), n = 13] and those who were unable to do so [unable group (UG), n = 11]. METHODS: All subjects performed OLS unaided and OLS with front support (OLS-FS) using one hand for 1 min each. We estimated leg muscle activity [mean and maximum % root mean square (%RMS)] and body sway (total, X-axis, and Y-axis path lengths) for both tests. %RMS was calculated according to the results of the maximum voluntary isometric contraction test. RESULT: The overall average mean and maximum %RMS for the tibialis anterior muscle was larger in UG than in AG. In AG, tibialis anterior muscle mean and maximum %RMS and body sway was larger during OLS than during OLS-FS. Total and X-axis path lengths were larger during the first 20 s OLS phase in AG and the first 20 s OLS-FS phase in UG. CONCLUSION: These results highlight the need to differentiate between patients able and unable to perform OLS unaided for training because of differences in leg muscle activity.

ADJUSTMENT ERRORS IN ASCENDING AND DESCENDING PHASES OF TARGET LEVEL IN CONTROLLED FORCE EXERTION.

Hand grip force adjustment errors to ascending and descending phases of a sinusoidal target force in a controlled force exertion (CFE) test were measured and the laterality of responses evaluated. 75 men (M age = 19.6 yr., SD = 1.6) performed the CFE test after one practice trial by matching handgrip force to target level (5-25% of maximal grip force). The CFE errors in ascending and descending phases of the target force were calculated as the absolute differences between actual force and target force in each phase. There were significantly smaller CFE errors in the ascending phase for both dominant and non-dominant hands, but CFE error for the dominant hand was significantly smaller in both phases. Therefore, error in force exertion in the ascending and descending phases of the target force differed, and laterality influenced error in both phases.

Effect of shoes with rounded soft soles in the anterior-posterior direction on the center of pressure during static standing.

Shoes with curved rocker bottom soles may induce an unstable standing posture. This study was aimed to mainly examine the effect of such shoes on the center of pressure (COP) during static standing. Ten healthy young male adults had their COP measured during static standing with four types of shoe conditions (Stretch Walker(®): SW (shoes with curved rocker bottom soles), Masai Barefoot Technology®: MBT (similar to SW in form and material), more conventionally soled shoes with a typical toe-spring: MCS, and bare feet: BF) for 60s. The mean path length and mean velocity of Y (front-back) axis were significantly greater when wearing the MBT than when wearing the SW, and when wearing the SW than when BF or when wearing the MCS. In addition, mean velocity of X (left-right) axis, area surrounding root mean square, root mean square, and root mean square of Y-axis were significantly greater when wearing the MBT than when wearing the SW, MCS, or when BF. In conclusion, when wearing the MBT or SW with rounded sole, static standing posture becomes unstable because of their characteristics as compared with wearing MCS or when BF, but the MBT has a larger sway in the front-back direction than the SW.

Age-related and obstacle height-related differences in movements while stepping over obstacles.

BACKGROUND: This study aims to examine age-related and obstacle height-related differences in movements while stepping over obstacles. METHODS: The participants included 16 elderly and nine young women. Obstacles that were either 5 or 20 cm high were positioned at the center of a 4-m walking path. The participants were instructed to walk along the path as quickly as possible. The participants' movements were analyzed using a three-dimensional motion analysis system that recorded their movements as they walked and stepped over the obstacles. RESULTS AND CONCLUSIONS: Seven joint angles and the distances between the ground and six markers were examined in the initial contact and swing instants of the leading and trailing limbs. In the initial contact instant, the elderly women prepared for stepping with a lower toe height than the young women when stepping over the 20-cm obstacle. Trunk rotation was greater in the young women than in the elderly women. In the swing instant, the elderly women showed greater ankle dorsiflexion and hip adduction angles for the leading limb when stepping over the 20-cm obstacle. They moved the trailing limb with increased ankle dorsiflexion, knee flexion, hip flexion, and foot inversion to ensure that they did not touch the obstacle as they stepped over it. These movement patterns are characteristic of elderly individuals who cannot easily lift their lower limbs because of decreased lower-limb strength.

Relationship Between Jump Rope Double Unders and Sprint Performance in Elementary Schoolchildren.

According to dynamic analyses of muscle contraction, jump rope is a typical stretch-shortening cycle (SSC) movement. It has been reported that the relationship with SSC is higher in double unders than in single unders (basic jumps); however, the relationship between jump rope and sprint performances has not been extensively studied. To clarify this relationship in elementary schoolchildren, we compared the sprint speed and SSC ability of children who were grouped according to gender and ability. The subjects were 143 elementary fifth and sixth graders (78 boys, 65 girls). The consecutive maximal number of double unders, reactivity index (index of SSC ability) by Myotest, and 20-m sprint time were measured. According to the mean of jump rope records, the children were divided into a superior ability group (more than average + 0.5 SD) and an inferior ability group (less than average - 0.5 SD) for each gender. In both genders, a significant difference was found in the 20-m sprint time between the inferior and superior ability groups. The times for the superior ability groups (boys, 3.75 ± 0.23 seconds; girls, 4.02 ± 0.24 seconds) were excellent compared with the inferior ability groups (boys, 4.17 ± 0.32 seconds; girls, 4.23 ± 0.21 seconds). This effect size was higher in boys (1.44) than in girls (0.93). The reactivity index in the superior ability group was excellent compared with that in the inferior ability group. In conclusion, children who perform better in double unders are also faster during a 20-m sprint run. This tendency may be higher in boys. Classic jump rope training, such as double unders, should be effective as elementary plyometrics for improving the sprint ability of children.

Body sway and muscle activity during one-leg stance with help using a hand.

The authors examined the effects of the direction (front or lateral) and method (light touch [LT] or support [LS]) of hand help on body sway and muscle activity during 1-leg stance (OLS). Fifteen subjects performed OLS with hand help under 4 conditions (front LT, front LS, lateral LT, lateral LS) after conducting normal OLS. Center of pressure (COP) path length and electromyography (EMG) were recorded. When using the lateral help, the COP and EMG were significantly smaller with LS than with LT. When using the front help, a difference in help methods did not affect the COP, but the EMG of gastrocnemius was significantly smaller with LS than with LT. In conclusion, body sway and muscle activity during OLS markedly decrease with lateral LS.

The effect of aging on the center-of-pressure power spectrum in foam posturography.

To assess age-related frequency-domain characteristics of the sway of center of pressure (COP) in foam posturography, two-legged stance tasks were performed by 163 controls in 4 conditions: eyes open with and without foam rubber, and eyes closed with and without foam rubber. The areas under the curve (AUCs) of power spectral density of the COP were calculated across low frequency (≥0.02 Hz and <0.1 Hz, LF-AUC), middle frequency (≥0.1 Hz and <1 Hz, MF-AUC) and high frequency (≥1 Hz and <10 Hz, HF-AUC) ranges. We categorized the controls into 7 age groups and analyzed each AUC in the 4 conditions. MF- and HF-AUCs tended to show a difference between younger and older age-groups in all 4 conditions. Comparing the number of pairs in which a significant difference was shown, the condition with foam rubber, especially with eyes open, tended to highlight age-related changes. In the medial-lateral axis in the eyes open/foam rubber condition, the MF-AUC of the ≥ 75 years group was significantly larger than that of the 65-74 years group, and the MF-AUC of the 65-74 years group was significantly higher than that of the 55-64 years group, although there were no significant differences of MF-AUC among age groups under 54 years. In this condition, although HF-AUC did not change in groups over 35 years old, HF-AUC of each age group over 35 years old was significantly larger than that of the group under 24 years old. This result suggests that, in the medial-lateral axis in the eyes open/foam rubber condition, MF-AUC is specifically affected by age in late-middle-aged (ages 55-64) and older subjects, while HF-AUC is specifically affected by age in early-middle-aged (ages 35-44) subjects.

Power spectral analysis of postural sway during foam posturography in patients with peripheral vestibular dysfunction.

OBJECTIVE: To assess the frequency-domain characteristics of postural instability caused by peripheral vestibular dysfunction by performing a power spectral analysis of the center of pressure (COP) sway during foam posturography. METHODS: Data were obtained from 78 patients and 163 controls. Two-legged stance tasks were performed in 4 conditions: eyes open with and without foam rubber, and eyes closed with and without foam rubber. We estimated the power spectrum of the acceleration signal using the maximum entropy method. The areas under the curve (AUCs) of power spectral density of the COP were calculated across low-frequency (0.02 to 0.1 Hz, LF-AUC), middle-frequency (0.1 to 1Hz, MF-AUC), and high-frequency (1 to 10 Hz, HF-AUC) ranges. We performed binomial logistic regression analyses to see whether the AUCs of selected bandwidths of COP have a stronger association with the presence of peripheral vestibular dysfunction in comparison with the velocity and area in the eyes closed/foam rubber condition. RESULTS: In both the controls and patients, the MF-AUC was significantly larger than the LF-AUC or HF-AUC in the eyes closed/foam rubber condition. In this condition, the presence of peripheral vestibular dysfunction had a significantly positive relationship with MF-AUC and HF-AUC (p < 0.05) and the MF-AUC of the anterior-posterior axis showed a stronger association with the presence of peripheral vestibular dysfunction than area. CONCLUSION: An increase in activity at middle frequency movements could be characteristic of peripheral vestibular dysfunction when standing on foam rubber with the eyes closed.

Differences in muscle power between the dominant and nondominant upper limbs of baseball players.

We examined the differences in muscle power between the dominant and nondominant upper limbs of 33 healthy, right-handed, university baseball players (mean age, 20.4 ± 1.1 years) with an average baseball experience >11 years. After measuring maximal voluntary contraction (MVC) of hand grip, elbow flexion, and shoulder internal rotation in both upper limbs, the muscle power of each joint was measured at 40%, 50%, and 60% MVC. No significant differences were observed in the main factors affecting MVC and elbow flexion power loads between dominant and nondominant upper limbs. For handgrip power, load factors at 40% MVC in the dominant hand were lower than those at 60% MVC in the same hand and those at 50% and 60% MVC in the nondominant hand. Significant differences were observed in shoulder internal rotation power between dominant and nondominant upper limbs, with the dominant limb having greater power at all loads. Correlations between muscle power of both upper limbs for handgrip and elbow flexion were significant and moderately high at all loads. For shoulder internal rotation power, the degree of correlation was significant and moderately high at 40% MVC but low to moderate at 50% and 60% MVC. Therefore, baseball players have marked lateral dominance in shoulder internal rotation power unlike handgrip and elbow flexion power, although the relationship between shoulder internal rotation muscle powers of both upper limbs becomes lower with increasing load. The dominance of muscle power of each joint varied even in the same upper limb. It is thus beneficial for baseball players to train with even loads on both arms or adopt simultaneous workout of both arms after adjusting for strength differences.

Possibility of stretch-shortening cycle movement training using a jump rope.

Although jumping rope has been said to be a typical stretch-shortening cycle movement (SSC) from the dynamic analysis of muscle contraction, there are few research reports that focus on this point. Recently, the function of SSC of the legs with respect to the jumping movement has been evaluated using the rebound jump index (RJ-index). This study aimed to examine the possibility of using rope jumping in SSC training by comparing the RJ-index of the rebound jump (standard value) and the 2 different methods of rope jumping. The subjects included 76 healthy young men. Most subjects were involved in routine sports training 2-3 times per week. They performed the rebound jump (5 consecutive vertical jumps) and both a basic and a double-under jump with the jump rope, according to each participant's individual style (rhythm or timing). The RJ-index was calculated using the ground contact time and the jump height. The reliabilities of the RJ-index in the basic (intraclass correlation coefficient: 0.85) and double-under jump (0.92) were high, and the RJ-index of the latter (1.34 ± 0.24) was significantly higher than that of the former (0.60 ± 0.21). In the case of a group with inferior SSC ability, the RJ-index of the rebound jump only showed a significant correlation with the double-under but not with the basic jump. When using the RJ-index (1.97 ± 0.38) of the rebound jump as a criterion, the double-under-using about 70% of the SSC ability-may be effective for reinforcement of SSC ability.

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.

Changes in the physical functions of pre-frail elderly women after participation in a 1-year preventative exercise program.

AIM: The present study clarifies the effects of participation in a preventative health classroom program (exercise program) for 1 year on the physical functions of pre-frail elderly individuals in comparison with healthy elderly individuals. METHODS: Participants in the study included 28 elderly pre-frail female participants and 28 elderly healthy female participants. Participants engaged in the exercise program for 1 year. There was no significant age or physical differences between both groups. Before and after the exercise program, the following physical function tests were carried out: grip strength, one-legged balance with eyes open, 5-m walking time and a timed up & go (TUG). RESULTS: The pre-frail elderly group tested significantly lower in the one-legged balance with eyes open test and the TUG test compared with the healthy elderly group. The 5-m walking time test improved significantly in both groups, but the TUG improved only in the pre-frail elderly group. Conversely, the grip strength and one-legged balance with eyes open tests remained unchanged. CONCLUSION: Improvements in the TUG and 5-m walking time tests were found in the pre-frail elderly group after the 1-year exercise program. Their results in the TUG test might be greater than those among the healthy elderly individuals.

Effects of mild and severe knee joint pain on various activities of daily living in the female elderly.

This study aimed to examine the differences in the ability to perform various activities of daily living (ADLs) among groups with various knee problems. The participants consisted of 328 elderly females (age 60-94; mean age 76.1 years; standard deviation 6.2). The subjects were classified into three groups: those without knee pain, those with mild knee pain, and those with severe knee pain. ADLs with markedly higher (>97%) and lower (<38%) achievement rates in the group without knee pain were not significantly different among the three groups. Achievement rates of 40%-97% for ADLs were significantly lower in the group with severe knee pain than in the group without knee pain. In addition, the groups with mild and severe knee pain demonstrated significantly lower achievement rates of ascending and descending stairs and sitting up than the group without knee pain. In conclusion, regardless of the presence of absence of mild or severe knee pain, some ADLs are difficult to achieve, while others are easy. The elderly with severe knee pain find it difficult to achieve many ADLs. In addition, it is difficult for the elderly with mild and severe knee pain to ascend and descend stairs and to sit up.

Postural stability during one-leg stance on an unstable moving platform and its relationship with each leg.

This study examined the laterality of the supporting leg in postural stability during a one-leg stance test on an unstable moving platform and its practice effect. 30 male university students were evaluated using the omnidirection stability index (OSI) during a one-leg stance test on an unstable moving platform (three trials). The leg used when kicking a ball was defined as the manipulation leg (ML) and the supporting leg was defined as the non-manipulation leg (NML). According to the two-way repeated measures analysis of variance (ANOVA; trials x legs), a statistically significant difference was observed only on the leg factor, and OSI values of the second and third trials were less for the ML than the NML. The correlation between both legs was statistically significant but not high. The ML was superior to NML with regard to stability, and no practice effect with trials was evident in either leg.

The prevalence of falling and status of physical function among elderly individuals with locomotive and visual/hearing disorders.

In a super-aged society, the need for prevention of locomotor dysfunction is growing, and evidence for feasible preventive measures is thus required. This study aimed to examine the relationship between these disorders and the prevalence rates for falling and physical function status. Participants included 1182 community-dwelling elderly Japanese individuals aged 60 and older. Subjects were classified into four groups on the basis of the presence or absence of locomotive and visual/hearing disorders. Locomotive and visual/hearing organs disorders and physical function were assessed using a self-rated questionnaire. Competence level with activities of daily living (ADL) was used to assess physical function. Locomotive disorder was more prevalent in females than in males, and the presence of such disorders tended to have more influence on the risk of falling and decline in ADL function in females than in males. Locomotive disorders may have a greater effect on the lives of elderly females compared with elderly males. Although there was no significant odds ratio in the presence of multiple disorders, the prevalence rate of the multiple disorders increased with age and this increased the risk of falling also increases with age.

Age-related, interindividual, and right/left differences in anterior-posterior foot pressure ratio in preschool children.

BACKGROUND: This study aimed to examine age-related, interindividual, and right/left differences in anterior-posterior foot pressure ratio in 764 preschool children (364 boys and 400 girls) aged 3.5-6.5 years. METHODS: Subjects maintained an upright standing posture for 10 seconds on the Footview Clinic, an instrument designed to calculate the anterior-posterior foot pressure ratio. The ratio of anterior foot pressure in each subject's right and left feet was selected as a variable, and the mean of a 10 s measurement was used for analysis. RESULTS: The ratio of anterior foot pressure was significantly larger in the right foot than in the left foot. With regard to age, the ratio of anterior foot pressure was significantly larger in children aged over 4.5 years than in children aged 3.5 years. It was also larger in children aged 6 and 6.5 years than in children aged 4 years. Interindividual differences in variables were large, and coefficients of variance were highest in children aged 3.5 years and lowest in children aged 6.5 years. CONCLUSIONS: In conclusion, anterior foot pressure increases with age in preschool children. Interindividual differences in anterior foot pressure are large and tend to decrease with age. Furthermore, the anterior foot pressure is slightly higher in the right foot than in the left foot. These results will be useful for various studies, such as examining relationships between the anterior-posterior foot pressure ratio and factors, such as untouched toes, physical fitness, and level of exercise.

Age differences between the controlled force exertion measured by a computer-generated sinusoidal and a bar chart display.

It is important to develop an accurate method of measuring controlled force exertion. This study examined the age differences between the controlled force exertion measured by a sinusoidal waveform and a bar chart display. The participants comprised 175 right-handed male adults aged 20-86 years. The participants were divided into three age groups: young (n=53), middle-aged (n=71), and elderly (n=51). They matched the submaximal grip strength exerted by their dominant hand to changing demand values displayed as either a sinusoidal waveform or a bar chart appearing on a personal computer screen. The participants performed the controlled force exertion test three times with a 1-min inter-trial interval using their dominant hand. The dependent variable was the total sum of the percentage values of the differences between the demand value and grip exertion value for more than 25s. The coefficient of variance had almost the same range in all age groups in both displays (CVSW=28.0-36.9, CVBC=29.1-32.6), but the elderly group showed a somewhat higher value with the sinusoidal waveform. Significant correlations were found between the scores with sinusoidal waveform and bar chart displays in the young, middle-aged, and elderly groups (r=0.47-0.68), but the correlations did not differ significantly between the age groups. Scores over 1500% in sinusoidal and bar chart display were found in one and two participants, respectively, in the middle-aged group and in 12% and 16% of the participants, respectively, in the elderly group. Furthermore, among all participants, only 8% of participants in the elderly group scored over 1500% in both displays. Scores over 1500% in both displays are considered to be considerably worse in controlled force exertion than lower scores.