Pertti Era

Force Platform Measurements as Predictors of Falls among Older People – A Review

Background: Poor postural balance is one of the major risk factors for falling. A great number of reports have analyzed the risk factors and predictors of falls but the results have for the most part been unclear and partly contradictory. Objective data on these matters are thus urgently needed. The force platform technique has widely been used as a tool to assess balance. However, the ability of force platform measures to predict falls remains unknown. Objective: The purpose of this systematic review was to extract and critically review the findings of prospective studies where force platform measurements have been used as predictors of falls among elderly populations. Methods: The study was done as a systematic literature review. PubMed, the Cochrane Central Register of Controlled Trials, and CINAHL databases from 1950 to April 2005 were used. The review includes prospective follow-up studies using the force platform as a tool to measure postural balance. Results: Nine original prospective studies were included in the final analyses. In five studies fall-related outcomes were associated with some force platform measures and in the remaining four studies associations were not found. For the various parameters derived on the basis of the force platform data, the mean speed of the mediolateral (ML) movement of the center of pressure (COP) during normal standing with the eyes open and closed, the mean amplitude of the ML movement of the COP with the eyes open and closed, and the root-mean-square value of the ML displacement of COP were the indicators that showed significant associations with future falls. Measures related to dynamic posturography (moving platforms) were not predictive of falls. Conclusion: Despite a wide search only a few prospective follow-up studies using the force platform technique to measure postural balance and a reliable registration of subsequent falls were found. The results suggest that certain aspects of force platform data may have predictive value for subsequent falls, especially various indicators of the lateral control of posture. However, the small number of studies available makes it difficult to draw definitive conclusions.

Postural Balance in a Random Sample of 7,979 Subjects Aged 30 Years and Over

Background: Reliable normative data for force platform measurements of postural balance have not been available. Methods: Data on postural balance were collected from a representative nationwide sample of a Finnish population aged ≧30 years (n = 7,979). As part of a comprehensive health survey (Health 2000), postural balance was measured with the help of a force platform system in four test conditions: normal standing with eyes open and closed (both for 30 s), semi-tandem (20 s) and tandem stand with eyes open (20 s). In addition, balance abilities were also evaluated by a non-instrumented field test. Results: The main findings of this study indicated that the differences in balance between subjects belonging to different age categories were apparent already among young and middle-aged subjects. This is true, however, only for the more accurate force platform measurements, as the field test showed a clear ceiling effect up to 60 years of age. At higher ages both methods indicated a further, accelerating decline in balance function. In most cases, males tended to have more pronounced sway, as indicated by the speed and amplitude aspects of the movement of the center of pressure during the force platform registrations and these differences were larger in the older age groups. In contrast, in the field test a larger proportion of males were able to achieve the highest category (10 s in tandem stand) and the proportion of subjects unable to stand for a minimum of 10 s feet side by side was larger among females than males. These observations may partly be due to differences in the participation/acceptable performance in the different tests. In addition, the field test and force platform measurements may partially reflect different aspects of balance abilities. Conclusion: The results of the present study provide normative values for force platform balance tests at an age of 30 years and above. Deterioration in balance function clearly starts at relatively young ages and further accelerates from at about 60 years upwards. Due to systematic differences between males and females, separate normative values for both sexes are needed. Due to marked ceiling effects the field test can only be recommended for older individuals, aged ≧60. On the other hand, force platform registrations in the more demanding tests (semi-tandem and tandem stands) suffer from floor effects in the oldest age groups.

Physical Activity and the Changes in Maximal Isometric Strength in Men and Women from the Age of 75 to 80 Years

OBJECTIVE: To research the natural changes in maximal isometric strength, over a period of 5 years, in men and women aged 75 at baseline, and to study the effect of everyday physical activity on strength alterations.

Changes in Postural Balance in Frail Elderly Women during a 4-Week Visual Feedback Training: A Randomized Controlled Trial

Background: Balance training programs have not shown consistent results among older adults, and it remains unclear how different training methods can be adapted to frail elderly people. Objective: The purpose of this study was to investigate the effects of a 4-week visual feedback-based balance training on the postural control of frail elderly women living in residential care homes. Methods: Elderly women of two residential care facilities were randomized to an exercise group (EG, n = 20) and to a control group (CG, n = 7). The EG participated in training sessions three times/week for 4 weeks. The exercises were carried out with a computerized force platform with visual feedback screen. The dimensions of balance function studied were standing body sway, dynamic weight shifting, and Berg Balance Scale performance. Results: The EG showed significant improvement in balance functions. The performance time in dynamic balance tests improved on average by 35.9% compared with a 0.6% increase in the CG (p = 0.025–0.193). The performance distance in these tests decreased on average by 28.2% in the EG as compared with a 9.8% decrease seen in the CG. The Berg Balance Scale performance improved by 6.9% compared with a 0.7% increase in the CG (p = 0.003). The standing balance tests in the more demanding standing positions showed improvements in the EG, whereas similar changes in the CG were not found. Conclusions: Our findings suggest that balance training based on visual feedback improves the balance control in frail elderly women living in residential care, also enhancing the performance of functional balancing tasks relevant to daily living. The subjects were motivated to participate in the training, as indicated by the high compliance (97.5%) with the program.

Self-reported sleep duration and cognitive functioning in the general population

This study investigated the relationship between self‐reported sleep factors (sleep duration, insomnia, use of sleeping medicine, probable sleep apnoea and feelings of fatigue and tiredness) with cognitive functioning in 5177 people aged 30 years or older from a cross‐sectional representative sample of the adult population in Finland (The Finnish Health 2000 Survey). Previous studies have indicated a U‐shaped association between increased health risks and sleep duration; we hypothesized a U‐shaped association between sleep duration and cognitive functioning. Objective cognitive functioning was assessed with tasks derived from the Consortium to Establish a Registry for Alzheimer’s Disease test battery (verbal fluency, encoding and retaining verbal material). Subjective cognitive functioning and sleep‐related factors were assessed with questionnaires. Health status was assessed during a health interview. Depressive and alcohol use disorders were assessed with the Composite International Diagnostic Interview. Medication was recorded during the health examination. Short and long sleep duration, tiredness and fatigue were found to be associated with both objectively assessed and self‐reported decreased cognitive functioning. The association was stronger between sleep factors and subjective cognitive function than with objective cognitive tests. These data suggest that self‐reported habitual short and long sleep duration reflect both realization of homeostatic sleep need and symptom formation in the context of the individual’s health status.

REACTION AND MOVEMENT TIMES IN MEN OF DIFFERENT AGES: A POPULATION STUDY

Tests of psychomotor and motor speed at different levels of complexity were studied in random samples of men aged 31 to 35, 51 to 55, and 71 to 75 yr. The study was performed as a part of a larger research project on health and functional aging. Analyses indicated significantly slower responses among older men at all levels of test complexity (maximal knee extension velocity, tapping rate, simple and choice reaction and movement times). There were marked differences both between the youngest and the middle-aged groups and between the middle-aged and the oldest groups. Within the age groups high psychomotor and motor speed were associated with a favourable functioning of certain senses (vibration sensitivity and postural balance), with a high isometric muscular force, and with a high directly assessed aerobic capacity. The most important covariants of the speed functions within the age groups were, however, cognitive performance, length of education, and perceived health.

Determinants of isometric muscle strength in men of different ages

SummaryValues of maximal isometric strength of five muscle groups and associated factors including occupational status, life style and health were studied in three groups of men aged from 31 to 35, 51 to 55, and 71 to 75 years. The results indicated significant differences between the age groups in isometric handgrip, elbow flexion, knee extension, trunk extension and trunk flexion strength. In the youngest group, the manual workers tended to have higher strength values in all muscle groups than the lower and higher status white collar workers; whereas among the middle-aged and oldest men the manual workers tended to have the poorest performance. Good self-rated health and the intensity of physical exercise during leisure were positively associated with muscle strength in the youngest and middle-aged groups whereas in the oldest group the most important variable was home gymnastics. The multivariate structural equation models of isometric strength differed somewhat among the age groups and in these models the above-mentioned variables accounted for from 33% to 43% of the variance in isometric strength within the age groups. The results illustrated the most important factors associated with isometric strength in samples of men of different ages and also provided suggestions as to how these determinants might influence comparisons between different age groups in respect of muscle strength.

Fall Incidence in Frail Older Women after Individualized Visual Feedback-Based Balance Training

Background: The knowledge concerning balance training actually lowering fall rates among frail older persons is limited. Objective: The aim of this study was to examine the effects of a 4-week individualized visual feedback-based balance training on the fall incidence during 1-year follow-up among frail older women living in residential care. Methods: Twenty-seven older women from 2 residential care homes were randomized into exercise (n = 20) and control (n = 7) groups. Balance measurements were carried out before and after a 4-week training period and falls were monitored by monthly diaries for 1 year. An interview about fear of falling and physical activity was completed before and after the intervention and after the 1-year follow-up. Results: A positive effect of balance training on fall incidence was found. A dynamic Poisson regression model showed that during the follow-up the monthly risk of falling was decreased in the exercise group compared to controls (risk ratio 0.398, 95% CI 0.174–0.911, p = 0.029). In addition, the exercise group reported a reduced fear of falling and increased physical activity after a training period but these changes declined during the follow-up period. Conclusion: Individualized visual feedback-based balance training was shown to be a promising method for fall prevention among frail older women. High compliance (97.5%) with the training program showed that carefully targeted training programs can be carried out among older people with health limitations.

Impaired Muscle Strength in Female Adolescents and Young Adults Surviving Leukemia in Childhood

Background. With the improving cure rate in childhood malignancies, increasing interest has been focused on long‐term survivors. To evaluate late sequelae of childhood leukemia, the muscle strength of 43 young female survivors was investigated and compared with that of 69 healthy age‐matched women. The patients had been off therapy for 1 to 19 years.

Correlates of vibrotactile thresholds in men of different ages

ABSTRACT— As a part of a larger gerontological research project vibrotactile thresholds on the inner malleolus of the ankle were studied in 355 men aged 31–35, 51–55 and 71–75 years. The groups studied were random samples of men living in the town of Jyväskylä in Finland in the year 1981. The thresholds were assessed at three frequencies: 50 Hz, 100 Hz and 250 Hz. The thresholds were associated with age at all frequencies, the means of the threshold values being significantly higher in the older age groups. Within the age groups the thresholds correlated positively with height. In addition, reaction and movement time, leg extension velocity, and postural sway were associated with the thresholds. Neither general health status nor occupational or educational background, or living habits had significant influence on the thresholds within the age groups. The results suggest that the elevation of vibrotactile thresholds is an inherent manifestation of aging in the nervous system. In addition to age, the height of the respondents is among the factors that should be taken into account when interindividual comparisons are made, if the measurement is on distal parts of the body.