Postural control: differences between youth judokas and swimmers

AIM

Specific physical training may improve balance control. This study aims to explore the underlying mechanisms of balance control in young Judokas compared with the type of training that does not require balance skills (swimming).

METHODS

Nine young judokas and nine age-gender matched swimmers (10.5-17-year-old) participated in the cross-sectional study. Postural Stability was collected using force platform during 10 upright standing trials in each of the three conditions: eyes open, eyes closed, and standing on foam. The force platform data were sampled at a frequency of 100 Hz, than analyzed using summary statistics and Stabilogram-Diffusion Analysis (SDA) for mediolateral (ML) and anteroposterior (AP) directions.

RESULTS

The results show that Judokas have better stability than swimmers in eyes closed condition but lower stability while standing on foam, with no significant differences in eyes open condition. The long-term effective diffusion coefficient of the SDA was significantly lower in judokas in all three postural task conditions.

CONCLUSIONS

The results show that Judokas are able to cope with momentary loss of vision better than swimmers, and less able to compensate reduction in somatosensory cutaneous sensation (e.g. standing on foam). These results suggest that judokas are less visually dependent relying on their sensorimotor system compare with swimmers. judokas have a more effective closed-loop balance control thus able to minimize their sway. It seems that training includes unexpected perturbations of the postural control system, emphasizing sensorimotor adaptabilities.

An early botulinum toxin A treatment in subacute stroke patients may prevent a disabling finger flexor stiffness six months later: a randomized controlled trial

OBJECTIVE

The study asked whether an early botulinum toxin A (BTX-A) injection in subacute stroke patients may prevent a disabling finger flexor stiffness six months later.

DESIGN

Single-blind, randomized pilot study.

SETTING

Inpatient rehabilitation centre.

SUBJECTS

Eighteen stroke patients, interval 4-6 weeks, non-functional arm, Fugl-Meyer arm score (0-66) <20, beginning elevated finger flexor tone, randomly allocated to group A or B.

INTERVENTIONS

In group A patients 150 units BTX-A (Xeomin) injected into the deep and superficial finger (100 units) and wrist flexors (50 units), no injection in group B patients. Comprehensive rehabilitation in both groups.

MAIN MEASURES

Primary variable was the Modified Ashworth Scale score (0-5) of the finger flexors; secondary variables were whole arm muscle tone with REPAS (a summary rating scale for resistance to passive movement), its motor control with the Fugl-Meyer arm score, and a disability scale, blindly assessed at T0 (start), T1 (four weeks) and T6 (six months).

RESULTS

Homogeneous groups at T0. Significantly less finger flexor stiffness in the BTX-A group at T1 and T6, the mean (SD) Modified Ashworth Scale scores in group A (B) were: 1.7 ± 0.5 (1.6 ± 0.5) at T0; 0.4 ± 0.5 (1.9 ± 0.7) at T1; and 1.4 ± 0.7 (2.4 ± 0.9) at T6. Among the secondary measures, the disability score, namely the items pain and passive nail trimming, was lower in group A at T1 and T6.

CONCLUSIONS

The results indicate an effect of early BTX-A injection on finger flexor stiffness six months later, presumably attributable to a reduced contracture development. Effect size calculation suggests inclusion of at least 17 patients per group excluding drop-outs in a warranted placebo-controlled trial.

Age-related differences in lower-limb force-time relation during the push-off in rapid voluntary stepping

BACKGROUND

This study investigated the force-time relationship during the push-off stage of a rapid voluntary step in young and older healthy adults, to study the assumption that when balance is lost a quick step may preserve stability. The ability to achieve peak propulsive force within a short time is critical for the performance of such a quick powerful step. We hypothesized that older adults would achieve peak force and power in significantly longer times compared to young people, particularly during the push-off preparatory phase.

METHODS

Fifteen young and 15 older volunteers performed rapid forward steps while standing on a force platform. Absolute anteroposterior and body weight normalized vertical forces during the push-off in the preparation and swing phases were used to determine time to peak and peak force, and step power. Two-way analyses of variance ('Group' [young-older] by 'Phase' [preparation-swing]) were used to assess our hypothesis (P ≤ 0.05).

FINDINGS

Older people exerted lower peak forces (anteroposterior and vertical) than young adults, but not necessarily lower peak power. More significantly, they showed a longer time to peak force, particularly in the vertical direction during the preparation phase.

INTERPRETATIONS

Older adults generate propulsive forces slowly and reach lower magnitudes, mainly during step preparation. The time to achieve a peak force and power, rather than its actual magnitude, may account for failures in quickly performing a preventive action. Such delay may be associated with the inability to react and recruit muscles quickly. Thus, training elderly to step fast in response to relevant cues may be beneficial in the prevention of falls.

Palmitoylation of human FasL modulates its cell death-inducing function

Fas ligand (FasL) is a transmembrane protein that regulates cell death in Fas-bearing cells. FasL-mediated cell death is essential for immune system homeostasis and the elimination of viral or transformed cells. Because of its potent cytotoxic activity, FasL expression at the cell surface is tightly regulated, for example, via processing by ADAM10 and SPPL2a generating soluble FasL and the intracellular fragments APL (ADAM10-processed FasL form) and SPA (SPPL2a-processed APL). In this study, we report that FasL processing by ADAM10 counteracts Fas-mediated cell death and is strictly regulated by membrane localization, interactions and modifications of FasL. According to our observations, FasL processing occurs preferentially within cholesterol and sphingolipid-rich nanodomains (rafts) where efficient Fas–FasL contact occurs, Fas receptor and FasL interaction is also required for efficient FasL processing, and FasL palmitoylation, which occurs within its transmembrane domain, is critical for efficient FasL-mediated killing and FasL processing.

Application of the voluntary step execution test to identify elderly fallers

OBJECTIVES

To assess the use of the Voluntary Step Execution Test to identify fallers.

DESIGN

Cross-sectional retrospective.

SETTING

Two self-care, residential facilities.

PARTICIPANTS

a total of 100 healthy old volunteers (mean age = 78.4 +/- 5.7).

MEASUREMENTS

The study investigated the use of the Voluntary Step Execution Test to identify fallers under single and dual-task conditions. Berg Balance Test (BBS) and Timed Get Up and Go (TUG) were used to assess balance and gait function.

RESULTS

There were no significant differences found between fallers and non-fallers in BBS and TUG (50.5 +/- 4.6 versus 52.5 +/- 3.4 and 9.4 +/- 3.4 versus 7.98 +/- 2.3 respectively). There were no statistically significant differences between non-fallers and fallers across all step execution parameters under the single-task condition. However, adding cognitive load to the Voluntary Step Execution Test revealed statistically significant increases in duration of the preparatory phase, swing time and the time to foot-contact (P = 0.035;P = 0.033 and P = 0.037, respectively). Based on the coefficients of the logistic regression model participants with dual-task step execution times of > or =1,100 ms had five times the risk of falling than participants with execution times of <1,100 ms.

CONCLUSIONS

The study provides evidence that a simple, safe measure of step execution under dual-task conditions can identify elderly individuals at risk for falls.

Postural stability in the elderly: a comparison between fallers and non-fallers

BACKGROUND

the identification of specific risk factors for falls in community-dwelling elderly persons is required to identify older people at risk of falling.

OBJECTIVE

the aim of the study was to determine the ability of various biomechanical measures of postural stability to identify fallers in the elderly population.

METHOD

19 subjects (78.4 +/- 1.3 years old) who reported having fallen unexpectedly at least twice in the last 6 months, and 124 non-fallers (77.8 +/- 0.53 years old) participated in the study. Balance measurements were made in the upright position in six different conditions using a force platform, and the Limits of Stability Test was carried out. Static two-point discrimination (TPD) testing to the underside of the first toe was made to evaluate the innervation density of the slowly adapting receptors. Finally, maximal isometric lower limb strength was measured in major muscle groups. Repeated measures analysis of variance tests were performed to assess the mean differences between the two groups (fallers and non-fallers). The level of significance was set to 0.05.

RESULTS AND DISCUSSION

results suggest that control of balance in narrow base stance may be an important tool in identifying elderly fallers. The findings show an increase in mediolateral sway in narrow base stance in older people who experienced recurrent falls. Also, TPD appears to be impaired in elderly fallers (14.93 +/- 1.1 mm versus 12.98 +/- 0.3 mm).

CONCLUSIONS

simple and safe laboratory quantitative tests were able to differentiate between elderly fallers and elderly individuals who did not fall, suggesting a possible clinical application as a preliminary screening tool for predicting future risk of falling.

Effects of regular walking on postural stability in the elderly

BACKGROUND

Both age and lack of physical activity may be responsible for poor health and poor balance control. Conversely, physical activity may modulate postural control in elderly people.

OBJECTIVE

An observational study was performed in older adults to explore whether walking on a regular basis might prove to be beneficial not only to the cardiovascular system but also to maintaining a good balance.

METHODS

Twenty-two healthy older subjects walking on a regular basis (DW group) and 121 healthy control older subjects who did not walk regularly (NW group) were studied. The subjects included in the study were free from major gait and postural disorders. An instrumented force platform was used to measure the time-varying displacements of the center of pressure under eight static conditions and postural limit tests. An isometric test was performed to evaluate lower limb muscle strength, and a static two-point discrimination test evaluated the innervation density of the slowly adapting receptors of the sole of the first toe.

RESULTS

The DW group had a significantly better (p < 0.05) postural stability under static conditions than the NW group. There were no significant differences in postural limit tests and in two-point discrimination between the groups. The DW group had significantly higher values of ankle plantar flexor and knee extensor strengths, while there were no significant differences in ankle dorsiflexors and knee flexors. None of the DW group reported experiencing a fall during the previous 6 months compared with 16% in the NW group who reported at least two falls during the last half year.

CONCLUSIONS

Walking on a regular basis in old age may have the potential to modulate stability. It was found that healthy older subjects, who walked on a regular basis since their retirement, have better postural control, especially in their static balance, than those who do not. The laboratory results were accompanied by the important finding that although older subjects who walk on a regular basis walked much more than nonwalkers, they did not suffer from falls.

Age-related changes of postural control: effect of cognitive tasks

BACKGROUND

Postural control and falls in the elderly constitute a major health problem. The interest in balance deficits is growing, as concern about the rising costs of health care increases. This issue is particularly relevant to the elderly population in which falls occur most frequently. Postural control in the elderly was studied using a cognitive approach.

OBJECTIVE

The purpose of this study was to study the characteristics of central processing of postural control while performing cognitive tasks.

METHODS

A dual-task procedure was developed to estimate the level of automaticity of a quiet upright standing task. The effect of a concurrent attention-demanding task (modified Stroop test) on the efficiency of balance control in the elderly was determined using force platform and electromyography measurements.

RESULTS

It was found that there is an increase in postural sway in old subjects compared with young subjects when performing single tasks and dual-task tests. The results of the study demonstrate that postural adjustments require cognitive processing; young and old subjects showed similar interference effects on postural steadiness (postural sway) caused by the concurrent attention-demanding task. The results are corroborated by the hypothesis that a dual task gives information on the restoration of automaticity of postural control in old age by a central reorganization process. When performing a dual task tested on a narrow base of support, the old subjects decreased their body sway, while the younger did not. According to electromyography measurements, the older subjects increased their muscle activity in the tibialis anterior and soleus muscles, using slow-twitch motor units compared with the younger subjects.

CONCLUSIONS

Both alterations (cognitive and base of support) have a substantially greater effect on the elderly than on the young. The older subjects decreased their body sway by activating a cocontraction strategy of postural control around the ankle joint, probably because of the danger to their postural stability.

Comparative study of osteoarthritis of the contralateral knee joint of male amputees who do and do not play volleyball

OBJECTIVE

To assess the prevalence of osteoarthritis (OA) of the contralateral knee of men with traumatic amputation who do and do not participate in regular, vigorous physical activity.

METHODS

Three groups of patients were assessed. Group 1 consisted of 8 male amputee volleyball players. Group 2 consisted of 24 male amputees who do not play volleyball, and Group 3 was made up of 24 healthy controls matched by age and weight to Group 2. The prevalence of contralateral knee OA in Groups 1 and 2 was assessed by questionnaire, physical examination, and radiographs, and was compared with findings for Group 3.

RESULTS

The rate of OA in all amputees (Groups 1 and 2 together) was 65.6%, which was significantly higher than among the controls (p < 0.05). The most common findings among the amputees were patellar and medial osteophytosis of the tibiofemoral joint, with a tendency to medial narrowing of the tibiofemoral joint space.

CONCLUSION

Traumatic amputees have a higher prevalence of OA in the knee of the nonamputated leg than matched healthy controls.