Strategic alterations of posture are delayed in Parkinson’s disease patients during deep brain stimulation

Parkinson’s disease (PD) is characterized by rigidity, akinesia, postural instability and tremor. Deep brain stimulation (DBS) of the subthalamic nucleus (STN) reduces tremor but the effects on postural instability are inconsistent. Another component of postural control is the postural strategy, traditionally referred to as the ankle or hip strategy, which is determined by the coupling between the joint motions of the body. We aimed to determine whether DBS STN and vision (eyes open vs. eyes closed) affect the postural strategy in PD in quiet stance or during balance perturbations. Linear motion was recorded from the knee, hip, shoulder and head in 10 patients with idiopathic PD with DBS STN (after withdrawal of other anti-PD medication), 25 younger adult controls and 17 older adult controls. Correlation analyses were performed on anterior–posterior linear motion data to determine the coupling between the four positions measured. All participants were asked to stand for a 30 s period of quiet stance and a 200 s period of calf vibration. The 200 s vibration period was subdivided into four 50 s periods to study adaptation between the first vibration period (30–80 s) and the last vibration period (180–230 s). Movement was recorded in patients with PD with DBS ON and DBS OFF, and all participants were investigated with eyes closed and eyes open. DBS settings were randomized and double-blindly programmed. Patients with PD had greater coupling of the body compared to old and young controls during balance perturbations (p ≤ 0.046). Controls adopted a strategy with greater flexibility, particularly using the knee as a point of pivot, whereas patients with PD adopted an ankle strategy, i.e., they used the ankle as the point of pivot. There was higher flexibility in patients with PD with DBS ON and eyes open compared to DBS OFF and eyes closed (p ≤ 0.011). During balance perturbations, controls quickly adopted a new strategy that they retained throughout the test, but patients with PD were slower to adapt. Patients with PD further increased the coupling between segmental movement during balance perturbations with DBS ON but retained a high level of coupling with DBS OFF throughout balance perturbations. The ankle strategy during balance perturbations in patients with PD was most evident with DBS OFF and eyes closed. The increased coupling with balance perturbations implies a mechanism to reduce complexity at a cost of exerting more energy. Strategic alterations of posture were altered by DBS in patients with PD and were delayed. Our findings therefore show that DBS does not fully compensate for disease-related effects on posture.

Sensory Organization Test Conditions Influence Postural Strategy Rather than Footwear or Workload

Background: Postural strategies such as ankle, hip, or combined ankle-hip strategies are used to maintain optimal postural stability, which can be influenced by the footwear type and physiological workload. Purpose: This paper reports previously unreported postural strategy scores during the six conditions of the sensory organization test (SOT). Methods: Fourteen healthy males (age: 23.6 ± 1.2 years; height: 181 ± 5.3 cm; mass: 89.2 ± 14.6 kg) were tested for postural strategy adopted during SOT in three types of occupational footwear (steel-toed work boot, tactical work boot, low-top work shoe) every 30 min during a 4-h simulated occupational workload. Postural strategy scores were analyzed using repeated measures analysis of variance at 0.05 alpha level. Results: Significant differences among postural strategy scores were only evident between SOT conditions, and but not between footwear type or the workload. Conclusions: Findings indicate that occupational footwear and occupational workload did not cause a significant change in reliance on postural strategies. The significant changes in postural strategy scores were due to the availability of accurate and/or conflicting sensory feedback during SOT conditions. In SOT conditions where all three types of sensory feedback was available, the ankle strategy was predominantly adopted, while more reliance on hip strategy occurred in conditions with absent or conflicting sensory feedback.

Balance strategy in hoverboard control

This work investigates how people learn to perform lower limb control in a novel task with a hoverboard which requires maintaining dynamic balance. An experiment was designed to investigate the learning of balance and control strategies: i.e. hip versus ankle strategy. Motor learning was indicated by a decrease in total muscle activation and time to complete a trial. The results further show that participants with no prior experience of riding a hoverboard learn an ankle strategy to maintain their balance and control the hoverboard. This is supported by significantly stronger phase synchrony and lower dynamic time warping distance between the hoverboard plate orientation, that controls hoverboard motion, and the ankle angle when compared to the hip angle. A decrease of 14.2% in the co-activation of the muscles acting on the ankle joint also confirms the adoption of the ankle strategy. The adopted ankle strategy is robust to the foot orientation despite salient changes in muscle group activation patterns.

The Effect of Ankle Strategy Exercises on Static Balance in The Elderly

Decreased muscle strength is a musculoskeletal disorder in the elderly, resulting in slow movements and impaired physical mobility. Physical changes that occur in the elderly cause the risk of falling. This study analyzes the ankle strategy exercise's effect on static balance in the elderly at Regional Technical Implementation Unit (UPTD) Griya Werdha Surabaya. This study was Pre-Experimental with One Group Pre-Post Test Design. From the population, there were thirty-five respondents by simple random sampling. This study's independent variable was ankle strategy exercises with frequency three times a week within a month. The dependent variable was a static balance with the instrument Time Up Go (TUG) test. The authors analyzed the data with the Wilcoxon test. The study results showed a significant effect of the ankle strategy exercise on static balance in the elderly (p=0,000). The result showed a decrease in the number of elderly who have the high-risk of falling before the ankle strategy exercise (60% of elderly have a high risk of falling) and after the intervention (34% of elderly have a decreased risk of falling). The elderly should do the ankle strategy exercise independently or with assistant three times a week to improve their static balance and decrease their high-risk of falls.

Balance in the Blind: A Systematic Review

Purpose: This paper reviews the studies on balance in the blind. Methods: The paper comprehensively reviewed studies on balance in the blind from the following databases: PubMed, MEDLINE, Web of Science, ScienceDirect, Cochrane Central Register of Controlled Clinical Trials, Google Scholar, and Scopus, from 2001 to 2019. Also, other available papers were examined. Results: Out of 35 evaluated studies, 32 articles were fully represented and the rest were only summarized. These articles covered two issues: 1) balance adaptation in the blind, 2) the effects of training protocols on the balance in the blind. Conclusion: The blind suffer from poor balance. However, they tend not to differ from normal people, when sufficient data from the vestibular and proprioception systems are available. Also, balance in the blind improves by age, which increases the efficiency and maturity of vestibular and proprioception systems. The blind tend to be more reliant on the hip than ankle strategy. All the training protocols reviewed in this paper have positively affected balance in the blind. Nevertheless, it was impossible to determine the most efficient protocol, and further qualitative studies are required for this purpose.

Influences of heel height on human postural stability and functional mobility between inexperienced and experienced high heel shoe wearers

Background High heel shoes (HHS) can affect human postural control because elevated heel height (HH) may result in plantar flexed foot and limit ankle joint range of motion during walking. Effects of HH and HHS wearing experience on postural stability during self-initiated and externally triggered perturbations are less examined in the literature. Hence, the objective of the present study is to investigate the influences of HH on human postural stability during dynamic perturbations, perceived stability, and functional mobility between inexperienced and experienced HHS wearers. Methods A total of 41 female participants were recruited (21 inexperienced HHS wearers and 20 experienced HHS wearers). Sensory organization test (SOT), motor control test (MCT), and limits of stability (LOS) were conducted to measure participant’s postural stability by using computerized dynamic posturography. Functional reach test and timed up and go test were performed to measure functional mobility. The participants’ self-perceived stability was assessed by visual analog scale. Four pairs of shoes with different HH (i.e., 0.8, 3.9, 7.0, and 10.1 cm) were applied to participants randomly. Repeated measures analysis of variance was conducted to detect the effects of HH and HHS wearing experience on each variable. Results During self-initiated perturbations, equilibrium score remarkably decreased when wearing 10.1 cm compared with flat shoes and 3.9 cm HHS. The contribution of vision to postural stability was larger in 10.1 cm HHS than in flat shoes. The use of ankle strategy worsened when HH increased to 7 cm. Similarly, the directional control of the center of gravity (COG) decreased for 7 cm HHS in LOS. Experienced wearers showed significantly higher percentage of ankle strategy and COG directional control than novices. Under externally triggered perturbations, postural stability was substantially decreased when HH reached 3.9 cm in MCT. No significant difference was found in experienced wearers compared with novices in MCT. Experienced wearers exhibited considerably better functional mobility and perceived stability with increased HH. Conclusions The use of HHS may worsen dynamic postural control and functional mobility when HH increases to 3.9 cm. Although experienced HHS wearers exhibit higher proportion of ankle strategy and COG directional control, the experience may not influence overall human postural control. Sensory organization ability, ankle strategy and COG directional control might provide useful information in developing a safety system and prevent HHS wearers from falling.

Parametric Study of Changes in Human Balancing Skill by Repeated Balancing Trials on Rolling Balance Board

Dynamic balance conditions were realized by asking eight volunteers to stand on uniaxial balance board with adjustable geometry and to carry out 60 s long balancing trials. Four different balance board geometry were used, each associated with different difficulty level. Balancing trials were repeated five times weekly (learning period) in order to test improvement of balancing skill. The measurement was repeated eight weeks after the learning period in order to check the persistence of the balancing skill (confirmation session). Oscillations of ankle angle and hip angle were monitored by OptiTrack motion capture system and four stabilometry parameters were used to characterize improvement in balancing performance, namely, Standard Deviation (STD), Largest Amplitude (LA), Normalized Path Length (NPL) and Mean Power Frequency (MPF). STD and NPL show similar tendency to the preliminary expectations, therefore they can be considered as good measures to describe balancing performance. Results show that subjects used ankle strategy for the less difficult balance board configurations, while for the more difficult tasks, hip strategy was also involved. Changes in STD and NPL during the learning period showed that the improvement and the persistence in balancing skill is more significant for more difficult balancing tasks.

PERBEDAAN PENGARUH ANKLE STRATEGY EXERCISE DAN BALANCE EXERCISE TERHADAP PENINGKATAN KESEIMBANGAN DINAMIS PADA LANSIA

Latar Belakang : Lansia mengalami penurunan sistem Muskuloskeletal, salah satunya adalah penurunan kekuatan otot, bertambahnya usia penurunan sistem muskuloskeletal pada lansia mempunyai peran yang besar terhadap terjadinya jatuh pada lansia. lansia mempunyai pengaruh terhadap keseimbangan postural. Tujuan : Untuk mengetahui perbedaan pengaruh Ankle Strategy Exercise dan Balance Exercise terhadap peningkatan Keseimbangan Dinamis pada Lansia. Metode Penelitian : Jenis penelitian adalah quasi experimental pre and post two group design dengan sample berjumlah 30 orang yang kelompok yaitu kelompok 1 dengan perlakuan ankle strategy exercise dan kelompok 2 dengan perlakuan balance exercise. Kedua latihan ini dilakukan selama 4 minggu dengan frekuensi 3 kali seminggu. Alat ukur yang di gunakan untuk mengukur keseimbangan dinamis adalah TUGT (time up go test). Uji Normalitas menggunakan Saphiro Wilk Test dan uji Homoginitas data menggunakan Lavene’s Test. Hasil penelitian dianalisis dengan menggunakan uji Paired Sample T-test untuk mengetahui peningkatan keseimbangan dinamis pada kelompk I dan II serta uji Independent Sample T-test untuk mengetahui ada perbedaan pengaruh kelompok I dan II. Hasil : Uji dengan Paired Sample T-test untuk kelompok I nilai p = 0,001 artinya (p> 0,05) dan untuk kelompok II nilai p = 0,001 artinya (p> 0,05). Uji perbedaan pengaruh kelompok I dan II dengan Independent Sample T-test nilai p = 0,000 yang berarti (p < 0,05). Ada perbedaan pengaruh yang signifikan antara kelompok I dan II. Simpulan : ada perbedaan pengaruh Ankle Strategy Exercise dan Balance Exercise terhadap peningkatan keseimbangan dinamis pada lansia. Saran : peneliti dapat mengkombinasikan latihan-latihan yang dapat berpengaruh terhadap keseimbangan dinamis pada lansia. Kata Kunci : Ankle Strategy Exercise, Balance Exercise, Keseimbangan Dinamis